Biomedical subjects

J Johansson

Publications and source records attributed to J Johansson.

At least 91 records · Page 5Linked to original sources

PubMed1999

Self-report as a selection instrument in screening for cardiovascular disease risk.

INTRODUCTION: Cardiovascular disease (CVD) risk screening may rely partly on self-report information. The accuracy of self-reporting in relation to the actual risk factor status is insufficiently known. DESIGN: Self-report (yes, no, don't know) of presence of hypertension, hyperlipidemia, and overweight was compared to the corresponding risk factor data obtained by physical examination and blood analysis. The examinations carried out in a primary health care setting in Sweden were on a randomized population of 122 men and 127 women aged 20 to 60 years. RESULTS: Unawareness of hyperlipidemia was 71% in women and 56% in men, as compared to 29% or lower for the other risk factors. The sensitivity of self-report was 69% or higher for the other risk factors, with the exception of hypertension in women, where it was 29%. Specificity was generally high, except for hyperlipidemia. CONCLUSION: On a population level, self-reports of hypertension, hyperlipidemia, and overweight provide a feasible selection instrument by which a subpopulation with high risk factor frequency can be identified. However, the rate of misclassification is considerable. For hyperlipidemia, the benefit of self-reporting is presently limited, due to the high unawareness of this risk factor. Individual awareness and accurate knowledge about the presence or absence of risk factors needs to improve before self-reporting can be used as a reliable instrument in risk factor screening.

Adult↗

PubMed1999

Antiplasmin correlates to arterial reactivity in a healthy population of 35-year-old men and women.

OBJECTIVE: To study whether haemostasis function variables correlate with endothelial function and other vasomotion characteristics of the brachial artery in a randomly selected healthy population of 35-year-old men and women. DESIGN: Endothelial function was measured as flow mediated dilatation (FMD) of the brachial artery during reactive hyperaemia and the nonendothelial dependent dilatation after sublingual nitroglycerin (NTG) was administered. Haemostasis and fibrinolysis function were estimated by analysis of von Willebrand factor, plasminogen activator inhibitor-1, antiplasmin and fibrinogen. SETTING: A general medicine research centre and a university hospital. SUBJECTS: Randomly chosen men (n = 53) and women (n = 56). RESULTS: Univariate correlation analysis showed significant correlations between haemostasis factors, conventional risk factors for cardiovascular disease and indices of vasomotion of the brachial artery. In multivariate analysis, with haemostasis variables and conventional risk factors included, antiplasmin was the strongest explanatory variable for FMD. When antiplasmin was removed from the analysis, the r-value dropped from 0.46 to 0.35. Antiplasmin also correlated with NTG-induced dilatation (positively) and brachial diameter at rest (negatively), albeit less consistently. CONCLUSIONS: Antiplasmin correlates significantly and independently to FMD, reflecting endothelial function, and also to brachial artery diameter at rest and nitroglycerin-induced dilatation. In multivariate analysis these correlations of antiplasmin to arterial characteristics were stronger than for 'conventional' risk factors, such as smoking, blood pressure and serum cholesterol.

Adult↗

PubMed1999

Isolation and characterization of hydrophobic polypeptides in human bile.

Polypeptides were isolated from human bile by extraction with chloroform/methanol, followed by reversed-phase chromatography in methanol/ethylene chloride and gel filtration in chloroform/methanol. Peptides were characterized by SDS/PAGE, sequence analysis and matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. This identified haemoglobin alpha chain, ATP synthase lipid-binding protein subunit 9, an N-terminal fragment of mac25/insulin-like growth factor-binding protein 7 and an internal fragment of monocyte differentiation antigen CD14, all not described previously in bile. In addition, alpha1-antitrypsin, known in bile from previous work, was also identified. The hydrophobic character of haemoglobin alpha chain is not apparent from its amino acid sequence, but the other polypeptides all have major hydrophobic segments. These results show that several proteins are removed upon organic solvent extraction used for delipidation during the preparation of samples for proteome analysis. Several of the polypeptides found are unexpectedly present in bile, suggesting that specific excretion mechanisms may be involved.

Amino Acid Sequence↗

PubMed1999

Four years experience of a cardiovascular opportunistic screening and prevention programme in the primary health care in Sollentuna, Sweden.

OBJECTIVE: To study the feasibility of a cardiovascular prevention programme. DESIGN: Opportunistic screening for cardiovascular risk factors. Advice and treatment to reduce identified cardiovascular risk factors. Individually designed follow-up. SETTING: Primary health care in Sollentuna (51,000 inhabitants), Sweden. SUBJECTS: Visitors to health care centres. MAIN OUTCOME MEASURES: Feasibility and effectiveness to reduce identified cardiovascular risk factors. RESULTS: During 4 years 5622 persons, of whom 4655 (83%) were in the age group 20-60 years, participated in the programme. The prevalences of risk factors as smoking, overweight, hypertension, hypercholesterolaemia and hypertriglyceridaemia were high. At follow-up investigations, mean S-cholesterol levels were reduced by 7% among men and 10% among women. S-triglycerides were reduced by 24% and 42%, respectively. Diastolic blood pressures were reduced in men from 95 to 90 mmHg and in women from 94 to 88 mmHg. However, no effects on weight were noted and due to a low follow-up rate meaningful analysis of smoking habits was not possible. CONCLUSION: A programme for cardiovascular screening and prevention can be integrated in the primary health care system. Prevalent cardiovascular risk factors like hypercholesterolaemia, hypertriglyceridaemia and high blood pressure were significantly reduced after intervention.

Adult↗

PubMed1999

Is there a relationship between balance, gait performance and muscular strength in 75-year-old women?

OBJECTIVE: To see if there is a relationship between clinical and laboratory tests of balance, muscular strength and gait in elderly women. DESIGN: A randomized population-based study. SETTINGS: Malmö, Sweden. METHODS: We investigated balance with a simple test of standing on one leg, as well as a computerized balance platform. Muscular strength was tested by computerized dynamometer. Extension and flexion of the knee and dorsiflexion of the ankle were tested. We measured the time and number of steps taken to walk a certain distance and the subjects' height and weight. PARTICIPANTS: 418 randomly selected 75-year-old women, of whom 230 took part. RESULTS: There was no relation between the computerized balance tests and any of the other tests. The non-computerized balance test was correlated with gait time and number of steps (r = -0.50, P<0.001 and r = -0.40, P<0.001, respectively). Tests of extension and flexion, strength of the knee and ankle dorsiflexion were related to gait, speed and number of steps. Heavy women had poorer balance when assessed by the non-computerized test (r = -0.32, P<0.001) and with the computerized, stable platform, eyes-open test (r = 0.27, P<0.001) and eyes-closed test (r = 0.44, P<0.001). The heavier an individual was, the slower her gait and the shorter her steps, despite having stronger knee muscles. CONCLUSION: There is no relationship between the simple balance tests and computerized platform tests. Muscle strength of the leg is not necessarily linked to balance, but rather to gait performance.

Aged↗

PubMed1999

Alterations in protein expression caused by the hha mutation in Escherichia coli: influence of growth medium osmolarity.

The Hha protein belongs to a new family of regulators involved in the environmental regulation of virulence factors. The aim of this work was to study the effect of the hha mutation on the overall protein pattern of Escherichia coli cells by two-dimensional polyacrylamide gel electrophoresis. The growth medium osmolarity clearly influenced the effect of the hha mutation. The number of proteins whose expression was altered in hha cells, compared with wild-type cells, was three times larger at a high osmolarity than at a low osmolarity. Among the proteins whose expression was modified by the hha allele, both OmpA and protein IIAGlc of the phosphotransferase system could be identified. As this latter enzyme participates in the regulation of the synthesis of cyclic AMP and hence influences the catabolite repression system, we tested whether the expression of the lacZ gene was also modified in hha mutants. This was the case, suggesting that at least some of the pleiotropic effects of the hha mutation could be caused by its effect on the catabolite repression system.

Alleles↗

PubMed1999

Molecular genetic characterisation of frontotemporal dementia on chromosome 3.

We have previously localized a locus causing familial nonspecific dementia to the centromeric region of chromosome 3 in a pedigree from the Jutland area of Denmark. This pedigree shows anticipation. Here we present further analysis of these anticipation data which are suggestive of trinucleotide repeat expansion involvement. We also outline our strategies to clone the mutant gene via its putative associated trinucleotide repeat sequence.

Adult↗

PubMed1999

Carotid artery diameter correlates with risk factors for cardiovascular disease in a population of 55-year-old subjects.

BACKGROUND AND PURPOSE: We investigated whether, in a randomly selected population of 55-year-old men and women, there is a relationship between common carotid artery (CCA) diameter and intima-media (IM) thickness and conventional risk factors for cardiovascular disease such as gender, smoking, elevated blood lipids, and high blood pressure. METHODS: CCA diameter and IM thickness of the distal right and left CCAs were measured by high-frequency ultrasound methods. Fifty-seven men (73% of the invited men) and 47 women (62% of the invited women) participated. RESULTS: In the whole group the CCA diameter was correlated with gender (P<0.001), cholesterol (P=0.007), triglycerides (P<0.001), apoB (P<0.001), apoB/A-1 (P<0.001), systolic blood pressure (P=0. 001), and glucose (P=0.006). HDL was inversely correlated with mean CCA diameter (P=0.003). In men the CCA diameter was correlated with a combined risk factor score (P=0.005), systolic blood pressure (P=0. 011), platelet count (P=0.033), apoB (P=0.025), and occurrence of plaque (P=0.003). In women the CCA diameter was correlated with a combined risk factor score (P=0.010), systolic blood pressure (P=0. 033), body mass index (P<0.001), cholesterol (P=0.009), triglycerides (P=0.14), apoB (P=0.002), and apoB/A1 (P=0.003). IM thickness was correlated with systolic blood pressure (P<0.001). CONCLUSIONS: There are correlations between risk factors for cardiovascular disease and carotid artery diameter and IM thickness in both women and men in a population of 55-year-old subjects. The increased vessel diameter in subjects with cardiovascular risk factors may be a sign of attenuated vasoregulation, which could be an important factor during the development of atherosclerosis.

Age Factors↗

PubMed1999

Radioisotope evaluation of the esophageal remnant and the gastric conduit after gastric pull-up esophagectomy.

BACKGROUND: The act of swallowing after gastric pull-up esophagectomy has not been thoroughly investigated. The aim of this study was to evaluate deglutition in the esophageal remnant and in the gastric conduit in patients who have undergone this operation. METHODS: The residual radionuclide activity was measured 15 seconds after a swallow in the esophageal remnant and at intervals up to a maximum of 120 minutes after a swallow in the gastric conduit. The scintigraphic rate of transit of a bolus in both areas was compared in patients who had anastomosis in the neck (n = 15) versus patients who had anastomosis in the chest (n = 19). Comparisons were also made between patients with and without symptoms of dysphagia. The scintigraphic measurements were also correlated with anastomotic diameters, measured with use of a volumetric balloon insufflation method, at 3, 6, and 12 months after operation. RESULTS: There were no significant differences in esophageal residual radionuclide activity at 15 seconds after a swallow in the groups with anastomosis in the neck versus anastomosis in the chest, with 30% residual activity up to 12 months after operation in both groups (P = .24). In the patients as a whole the 50% gastric conduit emptying time of 44 to 61 minutes did not change during the first postoperative year (P = .12). There was no association between anastomotic diameter and residual activity in the remaining esophagus (P < .126). Moderate and severe dysphagia was reported in only a few patients, and there was no correlation between dysphagic symptoms and retention in the residual esophagus or slower emptying in the gastric conduit. CONCLUSIONS: The amount of peristaltic activity in the remaining esophagus after esophagectomy with gastric replacement is unaffected by the level of the anastomosis. The gastric conduit empties slowly in all patients, and there is no correlation between the rate of emptying and either anastomotic diameter or symptoms of dysphagia.

Analysis of Variance↗

PubMed1998

Apolipoprotein A-I binds and inhibits the human antibacterial/cytotoxic peptide LL-37.

The antibacterial and cytotoxic activity of the human cathelicidin peptide LL-37 is inhibited by plasma. Because LL-37 does not undergo rapid degradation in human plasma, we postulated that this inhibition results from binding of LL-37 to unidentified proteins. An LL-37 binding plasma protein has now been isolated by affinity chromatography. SDS-polyacrylamide gel electrophoresis of proteins that bound to an LL-37 column revealed one band with a molecular mass of about 26 kDa, and amino acid sequence analysis identified the protein as apolipoprotein A-I (apoA-I). Biomolecular interaction analysis using surface plasmon resonance showed that LL-37 and isolated apoA-I bind with an apparent Kd in the low micromolar range. 50 microM of apoA-I inhibits the antibacterial activity of 50 microM LL-37 by about 50% of the inhibition exhibited by plasma. In addition, anti-apoA-I IgG completely blocks the plasma inhibition of LL-37 antibacterial activity up to a peptide concentration of 25 microM and blocks most of the plasma inhibition at higher LL-37 concentrations. These results indicate that apoA-I is the main LL-37 binding protein in human plasma and may work as a scavenger of LL-37, thus suggesting a novel mechanism involved in the regulation of a cathelicidin peptide.

Amino Acid Sequence↗

PubMed1998

Determination of proteins, phosphatidylethanolamine, and phosphatidylserine in organic solvent extracts of tissue material by analysis of phenylthiocarbamyl derivatives.

Amino acid analysis of organic solvent extracts of tissue material has been evaluated for determination of protein content. Conventional ninhydrin-based analysis does not allow determination of a large number of lipid-rich samples. Therefore, the hydrolyzed samples were treated with phenylisothiocyanate and the phenylthiocarbamyl (PTC) derivatives obtained were separated by reverse-phase HPLC. With this method, analysis of many lipid-rich samples is feasible. In addition, phosphatidylethanolamine and phosphatidylserine can then be determined together with the amino acid constituents. The PTC/reverse-phase HPLC method was used for analysis of chloroform/methanol extracts of spinal cord, lung, and bile after chromatography on Lipidex 5000 in methanol/ethylene chloride, 4:1 (v/v). The chromatography profiles show that in all tissue samples the proteins elute before the phospholipids. Consequently, a single step of Lipidex 5000 chromatography can be used to purify polypeptides present in organic solvent extracts. Using pulmonary surfactant extracts (with about 98% phospholipids and 1-2% proteins), we find that individual contents of surfactant proteins B and C can be determined by amino acid analysis.

Amino Acids↗

PubMed1998

Structure and properties of surfactant protein C.

Pulmonary surfactant contains less than 1 wt% of the very non-polar surfactant protein C (SP-C). In most animal species the major form of SP-C is a 35-residue peptide chain which contains two thioester-linked palmitoyl groups, giving a total molecular mass of 4.2 kDa. Several minor variants of SP-C exist, formed from N-terminal truncation, lysine palmitoylation, methionine oxidation and C-terminal esterification. The primary structure is evolutionarily conserved and SP-C appears to be the only constituent which is unique to pulmonary surfactant, indicating important and specific functions. The three-dimensional structure in an aqueous mixed organic solvent determined by NMR spectroscopy revealed one continuous 37 A long alpha-helix encompassing residues 9-34 as the only regular structural element. The central 23 A of the helix contains exclusively aliphatic residues with branched side-chains, mainly valines, and exposes an all-hydrophobic regular surface. The size of the entire helix perfectly matches the thickness of a fluid dipalmitoylphosphatidylcholine membrane, and the all-hydrophobic part of the helix matches the acyl-chain part of such a bilayer. This supports a transmembrane orientation of SP-C in pulmonary surfactant bilayers. In a phospholipid monolayer, the SP-C helix is tilted, thereby maximizing the interactions with the lipid acyl-chains also in this environment. The palmitoylcysteines of SP-C, which are located in the flexibly disordered N-terminal octapeptide segment, appear to be important both for integrity of the alpha-helical structure and for functional properties. Since the conformation of the N-terminal part in a phospholipid environment is not known, the mechanisms whereby the SP-C thioester-linked palmitoyl chains affect structure and function remain to be determined.

Amino Acid Sequence↗

PubMed1998

Sample enrichment in a single levitated droplet for capillary electrophoresis.

This paper describes sample enrichment in a single levitated droplet for capillary electrophoresis (CE) analysis. The droplet was trapped in an acoustical field. The minute sample volumes needed for the enrichment procedure were precisely handled using a piezoelectric flow-through liquid microdispenser. Droplets with a volume of 65 pl were ejected from the device at a repetition rate ranging from one single droplet up to several hundreds per second. By counting the number of droplets ejected and accumulated in the levitated drop the sample volume was controlled. Through solvent evaporation the analytes were enriched in the diminishing droplet. The droplet was then injected into a CE capillary and the analytes, dansyl-Gly and dansyl-Val dissolved in ethanol, were separated in a 100 mM borate buffer (pH 9.0) utilising UV-absorption detection at 200 nm near the capillary outlet. Enrichment of 36000 sample droplets (2.3 microl) through solvent evaporation in the levitated drop resulted in a concentration limit of detection (CLOD) of 15 nM for the dansylated amino acids as compared to a CLOD of 2.5 microM which was achieved using standard hydrodynamic injection without preconcentration.

Electrophoresis, Capillary↗

PubMed1998

Synthetic peptide-containing surfactants--evaluation of transmembrane versus amphipathic helices and surfactant protein C poly-valyl to poly-leucyl substitution.

Pulmonary surfactant contains two hydrophobic proteins, SP-B and SP-C. With the aim of identifying synthetic SP-B and SP-C substitutes for replacement therapy of respiratory distress syndromes, we have studied two transmembrane peptides and two amphipathic peptides that are located in the plane of a phospholipid bilayer. One amphipathic peptide was designed by changing the amino acid sequence, but not the composition or size, of the 21-residue peptide KL4. This peptide, designated KL(2,3) from its spacing of nonpolar and polar residues, exhibited similar alpha-helical content as KL4 but was oriented along a phospholipid bilayer plane, in contrast to the transmembrane orientation of KL4 in the same environment. The second amphipathic peptide analyzed was succinyl-LLEKLLEWLK-amide (WMAP10). KL4 more efficiently accelerated the spreading of a mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (Pam2GroPCho)/phosphatidylglycerol (PtdGro)/palmitic acid (PamOH), 68:22:9 (by mass), at an air/water interface than did any of the amphipathic peptides. Similarly, KL4, but not KL(2,3), when present in an interfacial monolayer composed of Pam2GroPCho/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol, 7:3 (by mass), increased lipid insertion from subphase vesicles. An SP-C analogue, SP-C(Leu), with all helical valyl residues in native SP-C replaced with Leu and the palmitoylcysteines at positions 5 and 6 replaced with Ser, but otherwise with essentially the same primary structure as the native peptide, was analyzed. SP-C(Leu) exhibited similar alpha-helical content as native SP-C and a transmembrane orientation and, in contrast to poly-valyl-containing synthetic peptides, it folds into a helical conformation after acid-induced denaturation. SP-C(Leu) accelerated the spreading of Pam2GroPCho/PtdGro/PamOH, 68:22:9 (by mass), almost identically to native SP-C, and lowered the surface tension during rapid cyclic film compressions in a pulsating bubble surfactometer to near zero and 43 mN/m at minimum and maximum bubble size, respectively. Airway instillation of 2% (by mass) SP-C(Leu) combined with Pam2GroPCho/PtdGro/PamOH in preterm rabbit fetuses improved dynamic lung compliance by about 30% compared with untreated controls.

Animals↗

PubMed1998

Effects of recombinant apolipoprotein A-I(Milano) on aortic atherosclerosis in apolipoprotein E-deficient mice.

BACKGROUND: We previously reported marked inhibitory effects of recombinant apolipoprotein (apo) A-I(Milano)/phospholipid complex (A-I[Milano]/PC) on neointimal lesions in balloon-injured iliofemoral arteries of hypercholesterolemic rabbits. In this study, we tested the hypothesis that apo A-I(Milano)/PC would inhibit aortic atherosclerosis in apo E-deficient mice. METHODS AND RESULTS: Thirty-five apo E-deficient mice fed a high-cholesterol diet were included in the study. Control mice were killed at 20 (n=8) or 25 (n=7) weeks. Treated mice received 18 injections of either 40 mg/kg apo A-I(Milano)/PC (n=15) or PC only (n=5) intravenously every other day from 20 weeks until death at 25 weeks. Aortic atherosclerosis was identified with Sudan IV staining. Lipid and macrophage contents of the aortic sinus plaques were measured after oil-red O and Mac-1 antibody staining, respectively, and quantified with computed morphometry. In control mice, from 20 to 25 weeks, aortic atherosclerosis increased by 59% (11 +/- 1% versus 17 +/- 5% of the aortic surface, P=.002), and lipid content increased by 45% (22 +/- 8% versus 32 +/- 6% of plaque area, P=.02) without a significant change in macrophage content (10.8 +/- 2% versus 13.2 +/- 6%). Compared with 20-week-old untreated control mice, PC only-treated mice at 25 weeks demonstrated a 32% increase in aortic atherosclerosis (11 +/- 1% versus 15 +/- 4%, P=.01) and an increase in lipid content (22 +/- 8% versus 47 +/- 3%, P<.0001) without a change in macrophage content (10.8 +/- 2% versus 11 +/- 2%). In comparison with 20-week-old untreated control mice, 25-week-old apo A-I(Milano)/PC-treated mice demonstrated no increase in aortic atherosclerosis (11 +/- 1% versus 10 +/- 4%, P=NS), a 40% reduction in lipid content (22 +/- 8% versus 13 +/- 8%, P=.01), and a 46% reduction in macrophage content (10.8 +/- 2% versus 5.8 +/- 2.9%; P=.03). Serum cholesterol levels were markedly elevated in all groups and did not change significantly with apo A-I(Milano)/PC or PC only. In vitro, apo A-I(Milano)/PC stimulated cholesterol efflux from cholesterol-loaded FU5AH hepatoma cell lines in a dose-dependent manner, whereas PC only or PC-free apo A-I(Miano) had no effect. CONCLUSIONS: Recombinant A-I(Milano)/PC prevented progression of aortic atherosclerosis and reduced lipid and macrophage content of plaques in apo E-deficient mice despite severe hypercholesterolemia. Thus, A-I(Milano)/PC may have a role in inhibiting progression and promoting stabilization of atherosclerosis.

Animals↗

PubMed1998

Secondary structure and limited proteolysis give experimental evidence that the precursor of pulmonary surfactant protein B contains three saposin-like domains.

The 42 kDa precursor of surfactant protein B generates the 79 residue mature SP-B polypeptide, which belongs to the family of saposin-like proteins and has unique functional roles in pulmonary surfactant. From sequence comparisons it has been suggested that proSP-B, in addition to SP-B, contains two saposin-like domains, but their existence has until now not been experimentally verified. The 381 residue human proSP-B was now fused to an N-terminal poly-His tag, expressed in Escherichia coli, and purified from inclusion bodies by resolubilisation with 2.5% (w/v) SDS and, after removal of SDS, subsequent metal affinity chromatography. Recombinant proSP-B thus obtained exhibits about 35% alpha-helical structure in sodium phosphate buffer and is proteolytically cleaved preferentially between the three saposin-like domains. These results experimentally support that proSP contains, in addition to SP-B, two further saposin-like domains.

Animals↗

PubMed1998

Conformation-dependent antibacterial activity of the naturally occurring human peptide LL-37.

The influence of ion composition, pH, and peptide concentration on the conformation and activity of the 37-residue human antibacterial peptide LL-37 has been studied. At micromolar concentration in water, LL-37 exhibits a circular dichroism spectrum consistent with a disordered structure. The addition of 15 mM HCO3-, SO42-, or CF3CO2- causes the peptide to adopt a helical structure, with approximately equal efficiency, while 160 mM Cl- is less efficient. A cooperative transition from disordered to helical structure is observed as the peptide concentration is increased, consistent with formation of an oligomer. The extent of alpha-helicity correlates with the antibacterial activity of LL-37 against both Gram-positive and Gram-negative bacteria. Two homologous peptides, FF-33 and SK-29, containing 4 and 8 residue deletions at the N terminus, respectively, require higher concentrations of anions for helix formation and are less active than LL-37 against Escherichia coli D21. Below pH 5, the helical content of LL-37 gradually decreases, and at pH 2 it is entirely disordered. In contrast, the helical structure is retained at pH over 13. The minimal inhibitory concentration of LL-37 against E. coli is 5 microM, and at 13-25 microM the peptide is cytotoxic against several eukaryotic cells. In solutions containing the ion compositions of plasma, intracellular fluid, or interstitial fluid, LL-37 is helical, and hence it could pose a danger to human cells upon release. However, in the presence of human serum, the antibacterial and the cytotoxic activities of LL-37 are inhibited.

Animals↗

PubMed1998

Analysis of variant forms of porcine surfactant polypeptide-C by nano-electrospray mass spectrometry.

Electrospray (ES) mass spectrometry has been used to analyse preparations of porcine pulmonary surfactant polypeptide-C (SP-C). A number of variant forms of the native 35-residue dipalmitoylated peptide were detected including (a) C-terminally methylated SP-C, (b) C-terminally methylated and methionine oxidized SP-C, (c) N-terminally truncated, C-terminally methylated and methionine oxidized SP-c, (d) C-terminally elongated, C-terminally methylated and methionine oxidized SP-C, and (e) tripalmitoylated, C-terminally methylated and methionine oxidized SP-C. C-terminal methylation and methionine oxidation are probably a consequence of the sample handling procedure. The occurrence of the C-terminally elongated form of SP-C has implications for the in vivo processing of proSP-C and the Tandem mass spectrometry (MS/MS) was used to confirm the amino acid sequence of SP-C and the presence of palmitoyl groups covalently linked to the peptide. Some of the structures of the variant forms of SP-C were determined by MS/MS.

Amino Acid Sequence↗