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PubMed2006

Active fragments of the antihemorrhagic protein HSF from serum of habu (Trimeresurus flavoviridis).

Certain snakes have antihemorrhagic proteins in their sera. Habu serum factor (HSF), an antihemorrhagic protein isolated from the serum of the Japanese habu snake (Trimeresurus flavoviridis) is composed of two cystatin-like domains (D1 and D2) and a His-rich domain, and it inhibits several snake venom metalloproteinases (SVMPs). The activity of HSF can be abolished by trinitrophenylation of Lys residues with 2,4,6-trinitrobenzene sulphonic acid. Upon complex formation of HSF with SVMP, however, the loss of its inhibitory activity by the chemical modification was suppressed, and Lys(15), Lys(41), and Lys(103) residues in HSF were not trinitrophenylated. In order to identify the domain that is critical to the inhibitory activity on SVMPs, native HSF was digested with papain followed by cleavage with cyanogen bromide, yielding a low-molecular mass fragment that was composed of two peptide chains (residues 5-89 and 312-317) linked by a disulfide bond. This fragment inhibited several SVMPs and showed significant antihemorrhagic activity. This indicates that the N-terminal half of D1 is indispensable for the antihemorrhagic activity of HSF. Furthermore, a three-dimensional model of two cystatin-like domains constructed by the homology modeling has indicated that three Lys residues (15, 41, and 103) are exposed to the same surface of HSF molecule.

Amino Acid Sequence↗
PubMed1997

Animal models of cerebral beta-amyloid angiopathy.

Cerebral amyloid angiopathy (CAA) is a significant risk factor for hemorrhagic stroke in the elderly, and occurs as a sporadic disorder, as a frequent component of Alzheimer's disease, and in several rare, hereditary conditions. The most common type of amyloid found in the vasculature of the brain is beta-amyloid (A beta), the same peptide that occurs in senile plaques. A paucity of animal models has hindered the experimental analysis of CAA. Several transgenic mouse models of cerebral beta-amyloidosis have now been reported, but only one appears to develop significant cerebrovascular amyloid. However, well-characterized models of naturally occurring CAA, particularly aged dogs and non-human primates, have contributed unique insights into the biology of vascular amyloid in recent years. Some non-human primate species have a predilection for developing CAA; the squirrel monkey (Saimiri sciureus), for example, is particularly likely to manifest beta-amyloid deposition in the cerebral blood vessels with age, whereas the rhesus monkey (Macaca mulatta) develops more abundant parenchymal amyloid. These animals have been used to test in vivo beta-amyloid labeling strategies with monoclonal antibodies and radiolabeled A beta. Species-differences in the predominant site of A beta deposition also can be exploited to evaluate factors that direct amyloid selectively to a particular tissue compartment of the brain. For example, the cysteine protease inhibitor, cystatin C, in squirrel monkeys has an amino acid substitution that is similar to the mutant substitution found in some humans with a hereditary form of cystatin C amyloid angiopathy, possibly explaining the predisposition of squirrel monkeys to CAA. The existing animal models have shown considerable utility in deciphering the pathobiology of CAA, and in testing strategies that could be used to diagnose and treat this disorder in humans.

Alzheimer Disease↗
PubMed2002

Increased cell density decreases cysteine proteinase inhibitor activity and increases invasive ability of two prostate tumor cell lines.

The ability of a cancer cell to metastasis to a distant site is partly dependent on the secretion of matrix degrading enzymes. The lysosomal cysteine proteinases, cathepsins B and L, have been shown to be secreted by a number of cancer cells and have been implicated in metastasis. Cathepsins B and L are regulated by a class of inhibitors known as the cystatins; aberrant cystatin activity has also been shown in a number of cancer cells. Two prostate cancer cell lines, PC3 and DU145, and a normal prostate epithelial cell (NPC) culture were used to determine the importance of cathepsins L+B and cysteine proteinase inhibitor (CPI) activity in the ability of each cell line to invade the reconstituted basement membrane, Matrigel. Cathepsin L+B and CPI activities were evident in the cell extract and conditioned media of PC3, DU145 and NPC; however, only the cancer cell lines PC3 and DU145 exhibited invasive ability. Invasive ability was partially inhibited following exposure of PC3 and DU145 cells to the CPI, E-64. Since environmental factors such as cell-cell interactions are responsible for mediating the expression of a number of genes involved in metastasis, the effects of cell density on cathepsin and CPI activities and invasive ability were also determined. CPI activity decreased and invasive ability increased with increasing cell density. We conclude that cathepsin L+B plays a significant role in the invasive ability of the two prostate cancer cell lines, PC3 and DU145. This may be due to decreased regulation by endogenous CPIs whose activity diminishes at high cell densities.

Adenocarcinoma↗
PubMed1988

Characterization of extracellular matrix in non-Hodgkin's lymphomas.

Basement membrane proteins laminin, type IV collagen and aminoterminal propeptide of type III collagen (type III pN-collagen) are important components of extracellular matrix of normal lymph nodes; they are present in reticular fibres and in the walls of blood vessels and sinuses. We have studied the distribution of these proteins in 45 cases of non-Hodgkin's lymphomas representing different types of Kiel classification. Light microscopic immunohistochemistry was used on sections from formalin fixed, paraffin embedded biopsy specimens. Reticular cells were identified by using antibodies against S-100 protein, a marker for dendritic and interdigitating reticulum cells, and against cystatin A for the demonstration of follicular dendritic reticulum cells. The findings of the immunohistochemical stainings were generally similar in the different lymphoma types. Thus the method for the demonstration of extracellular matrix proteins could not give obvious aid for lymphoma classification. BM stainings proved to be efficient in the demonstration of sinuses. Marginal and medullary sinuses of the nodal cases were either totally or partly spared and open also in the cases in which there was extracapsular growth. The fibre content was variable, but generally the distribution of all the three extracellular matrix proteins was comparable with each other and mainly corresponded with the pattern seen in conventional Gomori's reticulin stain. This also holds for the tumor tissue infiltrated through the capsule and for extranodal cases. Areas of sclerosis of some cases contained only type III pN-collagen. Reticular fibres were at places seen to be closely associated with cells of spindle or dendritic shape. A few reticulum cells could be found to show cytoplasmic staining for laminin, type IV collagen and type III pN collagen. This finding suggests that the cells are synthetizing these proteins. The amount of cells staining for cystatin A or S-100 protein did not generally correlate with the amount of fibres, and most of the stained cells were not closely associated with fibres. The results show that in non-Hodgkin's lymphomas basement membrane proteins and type III pN-collagen are important components of reticular fibres. Results also indirectly support the main role of fibroblastic reticulum cells in the production of the fibres.

Adolescent↗
PubMed1999

Cisternal S100 protein and neuron-specific enolase are elevated and site-specific markers in intractable temporal lobe epilepsy.

In the brain, S100 protein and neuron-specific enolase (NSE) are mainly found in glial cells and neurons, respectively. We investigated concentrations of S100 protein and NSE in cisternal cerebrospinal fluid obtained during implantation of foramen ovale electrodes in eight patients with temporal lobe epilepsy (TLE). In addition, the meningeal markers cystatin-C and beta-trace as well as total protein were measured. Patients with trigeminal neuralgia (TN) undergoing glycerol rhizotomy served as controls. S100 protein and NSE levels ipsilateral to the site of seizure onset were significantly higher than in TN. Contralateral TLE values were also markedly but not significantly elevated. The meningeal markers cystatin-C and beta-trace protein as well as total protein did not differ in TLE and TN. We conclude that interictal temporal lobe dysfunction corresponds with neuronal and glial marker elevations in the extracellular space and that site-specific elevations may predict the site of seizure origin biochemically.

Adult↗
PubMed1998

The cysteine protease activity of Colorado potato beetle (Leptinotarsa decemlineata Say) guts, which is insensitive to potato protease inhibitors, is inhibited by thyroglobulin type-1 domain inhibitors.

High levels of protease inhibitors are induced in potato leaves by wounding. These inhibitors, when ingested by Colorado potato beetle (Leptinotarsa decemlineata Say) larvae, induce expression of specific proteolytic activities in the gut. Induced protease activities cannot be inhibited by potato inhibitors and thus enable the insects to overcome this defence mechanism of potato plants. The induced aminopeptidase and endoproteolytic activities both have the characteristics of cysteine proteases. Twenty-one protein inhibitors of different structural types have been examined for their ability to inhibit these activities in vitro. Members of the cystatin superfamily were found to be poor inhibitors of the induced endoproteolytic activities, except for the third domain of human kininogen, which was a fairly strong inhibitor (75% inhibition). The strongest inhibition (85%) of induced endoproteolytic activity was obtained using structurally different thyroglobulin type-1 domain-like inhibitors--equistatin and MHC class II-associated p41 invariant fragment. Experiments performed using three synthetic substrates for endoproteases gave similar results and indicate the existence of at least different endoproteolytic enzymes resistant to potato inhibitors. The induced aminopeptidase activity can be inhibited only by stefin family of inhibitors in cystatin superfamily. In in vivo experiments, Colorado potato beetle larvae fed on equistatin-coated potato leaves were strongly retarded in their growth and almost 50% died after 4 days. This demonstrated the potential of equistatin to protect crops from insect attack.

Animals↗
PubMed1998

Antibody responses to fluke cysteine proteinases in Paragonimus- and Fasciola-infected rats.

IgG and IgM antibody responses to fluke cysteine proteinases in Paragonimus ohirai- and Fasciola sp.-infected rats were followed by means of cystatin capture ELISA using fluke excretory-secretory products for 10 weeks after infection. The specific IgG antibodies were detectable at week 2 postinfection in all P. ohirai-infected and some Fasciola-infected rats. Levels of specific IgG antibodies increased rapidly between week 2 and 6, and slightly thereafter, in both infected groups. From week 3, specific IgG antibody levels were higher in Fasciola-infected than P. ohirai-infected rats. Sera from infected rats did not react with heterologous cysteine proteinases throughout the infection periods. In both infected groups, the kinetic patterns of specific IgM antibody responses were similar to those of specific IgG antibody responses although the ELISA levels of the IgM antibody responses were much lower. In abnormal infections with P. ohirai metacercariae x-irradiated at 2 krad, the specific IgG antibodies were detectable at week 2 postinfection with similar ELISA values to normal P. ohirai infection, but thereafter increased little. In infections with P. westermani, for which the rat is not a suitable host, even stunted worms induced a comparable specific IgG antibody response, although the response was lower than in normal infections with P. ohirai. These results indicate that cystatin capture ELISA can distinguish clearly between Paragonimus and Fasciola infections which show immunodiagnostic cross-reactivity and is useful even in the early stages of the infection and in the infection of unsuitable hosts.

Animals↗
PubMed1989

Molecular cloning of cDNA for sarcocystatin A and analysis of the expression of the sarcocystatin A gene during development of Sarcophaga peregrina.

Sarcocystatin A is a cysteine proteinase inhibitor purified from the hemolymph of Sarcophaga peregrina larvae [Suzuki, T., & Natori, S. (1985) J. Biol. Chem. 260, 5115-5120]. We isolated a cDNA clone for sarcocystatin A and analyzed the structure and expression of the sarcocystatin A gene. Sarcocystatin A consists of 102 amino acid residues. Significant homology was found between amino acid sequences of sarcocystatin A and other mammalian cystatins, and highly conserved sequences among mammalian cystatins were also found in sarcocystatin A. Using cloned cDNA as a probe, we investigated expression of the sarcocystatin A gene during the development of Sarcophaga. Results showed that this gene was transiently activated in the very early embryonic stage and in the pupal stage, suggesting that sarcocystatin A participates in morphogenesis of larval and adult structures of Sarcophaga.

Amino Acid Sequence↗
PubMed2003

Recombinant human cathepsin H lacking the mini chain is an endopeptidase.

Human procathepsin H was expressed in the form of inclusion bodies in Escherichia coli. Following refolding and autocatalytic activation, a recombinant cathepsin H form lacking the mini chain was produced. Removal of the mini chain completely abolished aminopeptidase activity of the enzyme and largely increased its endopeptidase activity (approximately 40-fold). Similarly to cathepsin S, Bz-FVR-AMC (k(cat)/K(m) value of 1070 mM(-1) s(-1)) was found to be the preferred substrate of recombinant cathepsin H. However, substrate inhibition was observed at a higher substrate (Z-FR-AMC, Bz-FVR-AMC) concentration. Endopeptidase activity of recombinant cathepsin H was seen also with the protein substrate insulin beta-chain with the major cleavage site between Glu13-Ala14. Recombinant human cathepsin H was inhibited by chicken cystatin, stefin A, and stefin B with the K(i) values in the range of 0.05-0.1 nM, which is slightly tighter than the inhibition of purified cathepsin H by the same inhibitors. These results thus indicate that the cathepsin H mini chain is essential for the aminopeptidase activity of the enzyme but has only a minor effect on the inhibition by cystatins.

Amino Acid Sequence↗
PubMed2006

Comparative proteomics of nasal fluid in seasonal allergic rhinitis.

A comparative proteomic approach was applied to examine nasal lavage fluid (NLF) from patients with seasonal allergic rhinitis (SAR, n = 6) and healthy subjects (controls, n = 5). NLF samples were taken both before allergy (pollen) season and during season, and proteins were analyzed by two-dimensional gel electrophoresis (2-DE) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) after tryptic cleavage. Twenty proteins were selected and quantified. During allergy season, the levels of six sialylated isoforms of PLUNC (palate lung nasal epithelial clone) were lower in SAR patients than controls, as were the levels of six isoforms of von Ebner's gland protein (VEGP), including a previously undescribed form with N-linked glycosylation, and of cystatin S. PLUNC is a new innate immunity protein and VEGP and cystatin S are two endogenous proteinase inhibitors. By contrast, the levels of an acidic form of alpha-1-antitrypsin were higher in SAR patients than controls. One previously unidentified NLF protein was found in all samples from the SAR patients during allergy season but not in any sample before allergy season: this protein was identified as eosinophil lysophospholipase (Charcot-Leyden crystal protein/galactin 10). MS/MS analysis of the N-terminus of the protein showed removal of Met and acetylation of Ser. Altogether, these findings illustrate the potential use of proteomics for identifying protein changes associated with allergic rhinitis and for revealing post-translational modifications of such new potential markers of allergic inflammation.

Amino Acid Sequence↗
PubMed1998

Isolation and characterization of two forms of an acidic bromelain stem proteinase.

Two forms of an acidic bromelain proteinase isolated from crude bromelain, an extract from pineapple stem, were found by a two-step FPLC purification procedure. The basic main components were removed by cation exchange chromatography and the breakthrough fraction was further resolved by anion exchange chromatography into 15 protein fractions, only two of which, called SBA/a and SBA/b, were proteolytically active. These components were characterized by electrospray mass spectroscopy (ESMS), isoelectric focusing, N-terminal amino acid sequence analysis, monosaccharide analysis, and enzymatic parameters. The molecular masses of SBA/a and SBA/b were determined by ESMS to be 23,550 and 23,560, respectively. The isoelectric points (pI) of the two bands of SBA/a were 4.8 and 4.9; SBA/b focused as a single band at pI = 4.8. Partial N-terminal amino acid sequences (11 residues) were identical to SBA/a and SBA/b and identical with those of stem bromelain, the basic main proteinase of the pineapple stem, and fruit bromelain, the acidic main proteinase of the pineapple fruit. Both components are highly glycosylated; hydrolysis of SBA/a yielded about twofold more monosaccharide per protein than SBA/b. The comparison of the catalytic properties of SBA/a with those of SBA/b revealed no relevant differences in the hydrolysis of three peptidyl-NH-Mec substrates and in the inhibition profiles using chicken cystatin and E-64, indicating that these components can be considered as two forms of a single enzyme. Both forms are scarcely inhibited by chicken cystatin and slowly inactivated by E-64, hence are nontypical cysteine proteinases of the papain superfamily.

Amino Acid Sequence↗
PubMed1989

Bacterial growth blocked by a synthetic peptide based on the structure of a human proteinase inhibitor.

Cysteine proteinases are important not only in the intracellular catabolism of peptides and proteins and in the processing of prohormones and proenzymes, but also in the penetration of normal human tissue by malignant cells and possibly microorganisms, including viruses. Cystatin C is a human cysteine proteinase inhibitor present in extracellular fluids. We have synthesized peptide derivatives mimicking the proposed proteinase-binding centre of cystatin C and find that they irreversibly inhibit cysteine proteinases. Several bacteria produce proteinases, so we tested a tripeptide derivative (Z-LVG-CHN2) for in vitro anti-bacterial activity against a large number of bacterial strains belonging to thirteen different species. It was found to inhibit specifically the growth of all strains of group A streptococci. The susceptibility of these human pathogens to the peptide was compared with that to well-established anti-streptococcal antibiotics such as tetracycline and bacitracin. Moreover, the peptide was active in vivo against group A streptococci: mice injected with lethal doses of these bacteria were cured by a single injection of Z-LVG-CHN2. The cysteine proteinase produced by group A streptococci was isolated and found to be inhibited by Z-LVG-CHN2; moreover, excess proteinase relieved the growth inhibition caused by the peptide derivative, suggesting that the antibacterial activity of Z-LVG-CHN2 is due to inhibition of this cysteine proteinase. This strategy of blocking proteinases with peptide derivatives that mimic naturally occurring inhibitors could be useful in the construction of new agents against other microorganisms, including viruses.

Amino Acid Sequence↗
PubMed2002

Osteocalcin and the hormonal, inflammatory and metabolic response to major orthopaedic surgery.

Plasma osteocalcin, a marker of osteoblastic activity, decreases after major abdominal and gynaecological surgery. Increased cortisol secretion and other hormonal and inflammatory components of the peri-operative stress response may play a role in mediating this response. We assessed the effects of three different anaesthetic techniques on peri-operative osteocalcin concentrations. Thirty-six female patients undergoing elective total hip replacement were randomly assigned to receive propofol, propofol plus 'three-in-one' block or etomidate as part of a general anaesthetic technique. We measured plasma osteocalcin and serum cortisol, bone specific alkaline phosphatase, interleukin-6, plasma epinephrine, norepinephrine, plasma glucose and cystatin C concentrations for up to 3 days after surgery. Etomidate successfully inhibited the cortisol response to surgery but plasma osteocalcin declined in all patients. This was accompanied by increased plasma catecholamines, interleukin-6 and glucose concentrations, and decreased cystatin C-values. Inhibition of the cortisol response to surgery failed to prevent a decrease in plasma osteocalcin concentrations after surgery, suggesting that other factors such as cytokines or catecholamines may play a significant role.

Aged↗
PubMed2003

Increased circulating levels of proteinase 3 in patients with anti-neutrophilic cytoplasmic autoantibodies-associated systemic vasculitis in remission.

In systemic small vessel vasculitides, patients form autoantibodies against neutrophil granular proteins, anti-neutrophilic cytoplasmic autoantibodies (ANCA). Some correlation is seen between ANCA titre and disease activity, but whether this is cause or effect is still unknown. It has been reported that levels of proteinase 3 (PR3), one of the main ANCA antigens, are increased in patients with active disease. An increased level of circulating antigen could mean a predisposition to autoimmunity. In order to explore this we measured PR3 levels in patients with stable disease. In addition we measured neutrophil gelatinase-associated lipocalin (NGAL) as a specific marker of neutrophil degranulation, cystatin C as a marker of renal function as well as C-reactive protein (CRP), IL-6 and sTNFr1 as markers of inflammation. PR3, NGAL, IL-6 and sTNFr1 were measured in plasma by the ELISA technique. In the PR3 ELISA, we used anti-PR3 monoclonal antibodies as capture-antibodies and affinity-purified rabbit-anti-PR3 antibodies for detection. PR3-ANCA, myeloperoxidase (MPO)-ANCA, CRP and cystatin C were measured by routine methods. PR3 was significantly raised (P < 0.0001) in vasculitis patients (median 560 micro g/l, range 110-3,940, n = 59) compared with healthy blood donors (350 micro g/l, 110-580, n = 30) as well as disease controls (360, 110-580, n = 46). No correlation was seen with disease activity, inflammation or renal function. The raised NGAL levels correlated strongly with decreased renal function (r = 0.8, P < 0.001). After correcting for this, slightly increased levels (110, 42-340, n = 59) were observed compared with healthy blood donors (81, 38-130, n = 25), but not compared with the disease controls (120, 57-260, n = 48). In the disease controls, there was a significant correlation between NGAL and proteinase 3 (r = 0.3, p < 0.05), but this was not the case in the vasculitis patients. Whether patients had PR3-ANCA or MPO-ANCA was of no significance. In our measurements, we found significantly raised levels of PR3 in plasma from patients with small vessel vasculitis, regardless of ANCA specificity. This was not due to decreased renal function, ongoing inflammation or neutrophil activation. Plausible mechanisms for this include defects in the reticuloendothelial system, genetic factors and selective neutrophil degranulation or leakage.

Adult↗
PubMed2000

Biochemical characterization of human cathepsin X revealed that the enzyme is an exopeptidase, acting as carboxymonopeptidase or carboxydipeptidase.

Cathepsin X, purified to homogeneity from human liver, is a single chain glycoprotein with a molecular mass of approximately 33 kDa and pI 5.1-5.3. Cathepsin X was inhibited by stefin A, cystatin C and chicken cystatin (Ki = 1.7-15.0 nM), but poorly or not at all by stefin B (Ki > 250 nM) and L-kininogen, respectively. The enzyme was also inhibited by two specific synthetic cathepsin B inhibitors, CA-074 and GFG-semicarbazone. Cathepsin X was similar to cathepsin B and found to be a carboxypeptidase with preference for a positively charged Arg in P1 position. Contrary to the preference of cathepsin B, cathepsin X normally acts as a carboxymonopeptidase. However, the preference for Arg in the P1 position is so strong that cathepsin X cleaves substrates with Arg in antepenultimate position, acting also as a carboxydipeptidase. A large hydrophobic residue such as Trp is preferred in the P1' position, although the enzyme cleaved all P1' residues investigated (Trp, Phe, Ala, Arg, Pro). Cathepsin X also cleaved substrates with amide-blocked C-terminal carboxyl group with rates similar to those of the unblocked substrates. In contrast, no endopeptidase activity of cathepsin X could be detected on a series of o-aminobenzoic acid-peptidyl-N-[2,-dinitrophenyl]ethylenediamine substrates. Furthermore, the standard cysteine protease methylcoumarine amide substrates (kcat/Km approximately 5.0 x 103 M-1.s-1) were degraded approximately 25-fold less efficiently than the carboxypeptidase substrates (kcat/Km approximately 120.0 x 103 M-1.s-1).

Amino Acid Sequence↗
PubMed2003

Oryzacystatin I expression in transformed tobacco produces a conditional growth phenotype and enhances chilling tolerance.

A recent strategy for pest control in plants has involved transformation with genes encoding cysteine proteinase inhibitors (cystatins). Little is known, however, about the effects of constitutive cystatin expression on whole plant physiology. The present study using oryzacystatin I (OC-I) expression in transformed tobacco was designed to resolve this issue and also to test the effects on abiotic stress tolerance. All transformed plants expressing OC-I showed a conditional phenotype. A marked effect on stem elongation was observed in plants grown under low light intensities. After 7 weeks of growth at low light, the plants expressing OC-I were smaller with fewer expanded leaves and a slightly lower total biomass than empty vector controls or wild type plants. Maximal rates of photosynthesis (A(max)) were also decreased, the inhibitory effect being greatest in the plants with highest OC-I expression. After 12 weeks of growth at low light, however, the plants expressing OC-I performed better in terms of shoot biomass production, which was nearly double that of the empty vector or wild type controls. All plants showed similar responses to drought, however photosynthesis was better protected against chilling injury in plants constitutively expressing OC-I. Photosynthetic CO(2) assimilation was decreased in all plants following exposure to 5 degrees C, but the inhibition was significantly less in the OC-I expressing plants than in controls. The transformed tobacco plants expressing OC-I therefore show a phenotype-environment interaction with important implications for biotechnological applications.

Journal Article↗
PubMed1998

Measurement of the kinetics of protein uptake by proximal tubular cells using an optical biosensor.

BACKGROUND: The affinity and specificity of protein reabsorption by proximal tubular cells have been investigated using techniques for monitoring endocytosis, demonstrating a high capacity but low affinity process. It is not known whether uptake is through binding to a single binding site/receptor with differing affinities, or if there are several classes of binding sites receptors, each specific for differing proteins or groups, such as, high or low molecular weight proteins. METHODS: We have developed a novel technique for analyzing the kinetics of protein binding to tubular cells using a optical biosensor system. We have studied the binding of cultured LLCPK cells to albumin and RBP immobilized onto the sensor. By adding increasing concentrations of competing proteins [varying in molecular weight from 66,000 to 11,800 D and pI from 4.6 to 9.2 as represented by albumin, alpha1-microglobulin (alpha1M), retinol binding protein (RBP), cystatin C and beta2-microglobulin (beta2m)], specific and inhibitable cell binding was demonstrated. RESULTS: Equilibrium constants, KA, could be calculated from the reciprocal of the protein concentration causing 50% inhibition in binding rate. These were: albumin = 8.0 x 10(4) M(-1), alpha1M = 2.0 x 10(5) M(-1), RBP = 2.7 x 10(4) M(-1), cystatin C = 2.0 x 10(4) M(-1), beta2m = 4.2 x 10(3) M(-1). There were no significant differences between the measured KA's whether RBP or albumin were immobilized on the surface. CONCLUSIONS: All the proteins gave similar shaped inhibition profiles, suggesting that there is one binding site/receptor for all proteins studied, regardless of molecular weight or charge, but there are differing affinities for each protein.

Alpha-Globulins↗
PubMed2002

Total plasma homocysteine, age, systolic blood pressure, and cognitive performance in older people.

OBJECTIVES: To investigate the relationship between total plasma homocysteine (tHcy) levels, blood pressure (BP) variables, renal function, and measures of cognitive performance in older people. DESIGN: Initial cross-sectional analysis of a prospective cohort. SETTING: United Kingdom (Oxfordshire) community sample. PARTICIPANTS: One hundred fifty-eight community-dwelling volunteers aged 60 to 91. MEASUREMENTS: Neuropsychological tests (Cambridge Examination for Mental Disorders of the Elderly-Cognitive Section (CAMCOG), Mini-Mental State Examination (MMSE), and Geriatric Depression Scale), biochemical studies (tHcy, serum folate, vitamin B12, and serum cystatin C), BP, and other vascular risk factors. RESULTS: tHcy, age, systolic BP (SBP), and CAMCOG performance were significantly interrelated. tHcy was negatively associated with total CAMCOG score independent of years of education, serum folate, vitamin B12, and cystatin C levels. Older participants with higher tHcy levels had lower CAMCOG scores-especially men aged 70 and older. Higher tHcy levels were associated with poorer performance on the memory and perception subscores of CAMCOG but not with the other cognitive subscales or MMSE score. SBP also demonstrated a significant negative association with total CAMCOG and MMSE scores. CONCLUSIONS: These results suggest independent associations between tHcy (modified by age and sex) and SBP and cognitive performance in older people. Further longitudinal study will define whether optimization of tHcy and systolic BP contributes to the maintenance of cognitive performance with successful aging.

Age Factors↗