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PubMed1978

Characterization of pepsin-solubilized bovine heart-valve collagen.

Collagens extracted from heart valves by using limited pepsin digestion were fractionated by differential salt precipitation. Collagen types were identified by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, amino acid analysis and cleavage with CNBr. Heart-valve collagen was heterogeneous in nature, consisting of a mixture of type-I and type-III collagens. The identity of type-III collagen was established on the basis of (a) insolubility in 1.7 M-NaC1 at neutral pH, (b) behaviour of this collagen fraction on gel electrophoresis under reducing and non-reducing conditions, (c) amino acid analysis showing a hydroxyproline/proline ratio greater than 1, and (d) profile of CNBr peptides on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showing a peak characteristic for type-III collagen containing peptides alpha1(III)CB8 and alpha1(III)CB3. In addition to types-I and -III collagen, a collagen polypeptide not previously described in heart valves was identified. This polypeptide represented approx. 30% of the collagen fraction precipitated at 4.0 M-NaCl, it migrated between beta- and alpha1-collagen chains on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and its electrophoretic behaviour was not affected by disulphide-bond reduction. All collagen fractions from the heart valves contained increased amounts of hydroxylysine when compared with type-I and -III collagens from other tissues. The presence of beta- and gamma-chains and higher aggregates in pepsin-solubilized collagen indicated that these collagens were highly cross-linked and suggested that some of these cross-links involved the triple-helical regions of the molecule. It is likely that the higher hydroxylysine content of heart-valve collagen is responsible for the high degree of intermolecular cross-linking and may be the result of an adaptive mechanism for the specialized function of these tissues.

Amino Acids↗
PubMed1979

Purification and characterization of subcomponent C1q of the first component of bovine complement.

Bovine C1q, a subcomponent of the first component of complement, was purified in high yield by a combination of euglobulin precipitation, and ion-exchange and molecularsieve chromatography on CM-cellulose and Ultrogel AcA 34. Approx. 12-16mg can be isolated from 1 litre of serum, representing a yield of 13-18%. The molecular weight of undissociated subcomponent C1q, as determined by equilibrium sedimentation, is 430000. On sodium dodecyl sulphate/polyacrylamide gels under non-reducing conditions, subcomponent C1q was shown to consist of two subunits of mol.wts. 69000 and 62000 in a molar ratio of 2:1. On reduction, the 69000-mol.wt. subunit gave chains of mol.wts. 30000 and 25000 in equimolar ratio, and the 62000-mol.wt. subunit decreased to 25000. The amino acid composition, with a high value for glycine, and the presence of hydroxyproline and hydroxylysine, suggests that there is a region of collagen-like sequence in the molecule. This is supported by the loss of haemolytic activity and the degradation of the polypeptide chains of subcomponent C1q when digested by collagenase. All of these molecular characteristics support the structure of six subunits, each containing three different polypeptide chains, with globular heads connected by collagen triple helices as proposed by Reid & Porter (1976) (Biochem. J.155, 19-23) for human subcomponent C1q. Subcomponent C1q contains approx. 9% carbohydrate; analysis of the degree of substitution of the hydroxylysine residues revealed that 91% are modified by the addition of the disaccharide unit Gal-Glc. Bovine subcomponent C1q generates full C1 haemolytic activity when assayed with human subcomponents C1r and C1s.

Amino Acids↗
PubMed1984

Collagen composition of normal and myxomatous human mitral heart valves.

The collagens were studied in 13 normal and 19 myxomatous human mitral valves. The collagens of the valve were completely solubilized by using a method consisting of guanidinium chloride extraction, limited pepsin digestions and CNBr cleavage of the residue. The normal valves contained 74% type I, 24% type III and 2% type V collagen. The type I and type III collagens had similar solubility patterns, although only type I collagen was detected in the guanidinium chloride extract. Type V collagen was only detected in the first pepsin extract. The type I and III collagens had higher contents of hydroxylysine than did the same collagens from age-matched dermis. The two-dimensional electrophoretic 'maps' of CNBr-cleavage peptides showed low recoveries of the C-terminal alpha 1(I) CB6 and alpha 1(III) CB9 peptides, which are involved in forming intermolecular cross-linkages. Most of the reducible cross-linkages were present in large-Mr peptide complexes, and these complexes were shown by labelling with 125I to include the tyrosine-containing alpha 1(I) CB6 peptide. The myxomatous valves contained 67% type I, 31% type III and 2% type V collagens. There was a significant increase in the concentration of each type of collagen, which consisted of a 9% increase of type I collagen, a 53% increase of type III collagen and a 25% increase of type V collagen. The contents of hydroxylysine in type I and III collagens and the electrophoretic 'maps' of the CNBr-cleavage peptides involved in cross-linkages did not differ significantly from the results obtained from the normal valves. The biochemical findings suggest that there is an increased production of collagen, in particular type III collagen, and glycosaminoglycan as well as a proliferation of cells as part of a repair process in the myxomatous valves.

Collagen↗
PubMed1973

Isolation and characterization of two glycoproteins from patients with alveolar proteinosis.

The saline-insoluble particulate material obtained by pulmonary lavage from four patients with alveolar proteinosis was analyzed for total lipid (52%), protein (44%), and carbohydrate (4%). Sodium dodecyl sulfate-gel electrophoresis revealed only three major peptides in these patients. Molecular weights (from the gels) were 69,000, 62,000, and 36,000, and the latter two peptides were periodic acid-Schiff stain-positive. Amino-acid and sugar analyses were performed on the peptides cut from the gels and on peptides purified by Sephadex G-200 chromatography. The 69,000-molecular-weight peptide contained no carbohydrate. Antibody studies and aminoacid analysis indicated that it was albumin. The 62,000-molecular-weight peptide contained 1% hydroxyproline, 1% hydroxylysine, 10% glycine, and 9% carbohydrate. The 36,000-molecular-weight peptide contained 1.2% hydroxyproline, 1% hydroxylysine, 13% glycine, 1.4% sialic acid, 2.6% glucose, 2.4% galactose, 2% mannose, 0.8% fucose, 0.4% glycosamine, and 0.6% galactosamine. Proteins extracted from kidney glomeruli with similar amino-acid and carbohydrate composition have been observed previously.

Amino Acids↗
PubMed2000

Identification of the human mitochondrial oxodicarboxylate carrier. Bacterial expression, reconstitution, functional characterization, tissue distribution, and chromosomal location.

In Saccharomyces cerevisiae, the genes ODC1 and ODC2 encode isoforms of the oxodicarboxylate carrier. They both transport C5-C7 oxodicarboxylates across the inner membranes of mitochondria and are members of the family of mitochondrial carrier proteins. Orthologs are encoded in the genomes of Caenorhabditis elegans and Drosophila melanogaster, and a human expressed sequence tag (EST) encodes part of a closely related protein. Information from the EST has been used to complete the human cDNA sequence. This sequence has been used to map the gene to chromosome 14q11.2 and to show that the gene is expressed in all tissues that were examined. The human protein was produced by overexpression in Escherichia coli, purified, and reconstituted into phospholipid vesicles. It has similar transport characteristics to the yeast oxodicarboxylate carrier proteins (ODCs). Both the human and yeast ODCs catalyzed the transport of the oxodicarboxylates 2-oxoadipate and 2-oxoglutarate by a counter-exchange mechanism. Adipate, glutarate, and to a lesser extent, pimelate, 2-oxopimelate, 2-aminoadipate, oxaloacetate, and citrate were also transported by the human ODC. The main differences between the human and yeast ODCs are that 2-aminoadipate is transported by the former but not by the latter, whereas malate is transported by the yeast ODCs but not by the human ortholog. In mammals, 2-oxoadipate is a common intermediate in the catabolism of lysine, tryptophan, and hydroxylysine. It is transported from the cytoplasm into mitochondria where it is converted into acetyl-CoA. Defects in human ODC are likely to be a cause of 2-oxoadipate acidemia, an inborn error of metabolism of lysine, tryptophan, and hydroxylysine.

Adipates↗
PubMed2001

Silica-precipitating peptides from diatoms. The chemical structure of silaffin-A from Cylindrotheca fusiformis.

Two silica-precipitating peptides, silaffin-1A(1) and-1A(2), both encoded by the sil1 gene from the diatom Cylindrotheca fusiformis, were extracted from cell walls and purified to homogeneity. The chemical structures were determined by protein chemical methods combined with mass spectrometry. Silaffin-1A(1) and -1A(2) consist of 15 and 18 amino acid residues, respectively. Each peptide contains a total of four lysine residues, which are all found to be post-translationally modified. In silaffin-1A(2) the lysine residues are clustered in two pairs in which the epsilon-amino group of the first residue is linked to a linear polyamine consisting of 5 to 11 N-methylated propylamine units, whereas the second lysine is converted to epsilon-N,N-dimethyllysine. Silaffin-1A(1) contains only a single lysine pair exhibiting the same structural features. One of the two remaining lysine residues was identified as epsilon-N,N,N-trimethyl-delta-hydroxylysine, a lysine derivative containing a quaternary ammonium group. The fourth lysine residue again is linked to a long-chain polyamine. Silaffin-1A(1) is the first peptide shown to contain epsilon-N,N,N-trimethyl-delta-hydroxylysine. In vitro, both peptides precipitate silica nanospheres within seconds when added to a monosilicic acid solution.

Diatoms↗
PubMed2003

Vitamin C and bone markers: investigations in a Gambian population.

Vitamin C is an essential micronutrient. Absence from the diet will result in the deficiency disease scurvy, typically characterised by weakening of collagenous structures. High intakes of vitamin C have been associated with decreased incidence or severity of a number of diseases, including cancer and cardiovascular disease. These beneficial effects may be attributed to its antioxidant properties, although the exact mechanisms of action remain elusive. It is also unclear what intake levels are required for optimal health benefits. The task of defining optimal intakes is hindered by the lack of a reliable functional marker of tissue vitamin C status in man. Many different pathways have been investigated, but none of them have measurable outcome variables relating directly to scorbutic changes. The bone-collagen formation pathway has the potential to provide a functional index of tissue vitamin C adequacy. Vitamin C acts as a cofactor for the enzyme lysyl hydroxylase, which is required for the hydroxylation of lysine residues in procollagen chains. Pyridinoline is a mature collagen cross-link formed from three hydroxylysine residues, deoxypyridinoline is formed from two hydroxylysine and one lysine residue. Guinea-pig studies have shown an alteration in the pyridinium cross-link ratios in response to graded vitamin C intakes (Tsuchiya & Bates, 1998). In order to investigate whether these changes can be seen in a human population group, a study was carried out in rural Gambia, where there is a marked seasonal variation in dietary vitamin C. The present review discusses the rationale behind the study and presents some preliminary results.

Amino Acids↗
PubMed1967

Electron microscopic and biochemical characterization of collagen in blattarian insects.

The occurrence of collagen in the cockroach Leucophaea maderae has been demonstrated by electron optical and biochemical techniques. Electron micrographs of tissues of this and a related species (Blaberus craniifer) are presented and they show that collagenous-type fibers occur in the stroma of nonneural as well as neural organs of these insects. Hydroxyproline and hydroxylysine, amino acids considered to be "markers" for collagen, have been shown to be present in proteins extracted from material rich in neuroglandular tissue (corpus cardiacum plus corpus allatum). Trimmed carcasses of Leucophaea maderae have been shown to contain a protein or proteins soluble in hot trichloroacetic acid, with compositional characteristics similar to those of collagens in general, including diagnostic proportions of glycine, proline, hydroxyproline, and hydroxylysine. This collagen is not soluble in dilute acetic acid or in concentrated solutions of guanidinium chloride. It is measurably digested by bacterial collagenase.

Alanine↗
PubMed1965

STUDIES ON HUMAN ANTIBODIES. 3. AMINO ACID COMPOSITION OF FOUR ANTIBODIES FROM ONE INDIVIDUAL.

Antilevan, antidextran, antiteichoic acid, anti-"A" and normal gammaG, all isolated from a single human, as well as pooled gammaG and gammaM, were analyzed for amino acid content. Differences ranging from 7 to 32 residues were found among these antibodies in glycine, valine, leucine, tyrosine, arginine, lysine, and threonine content. These conspicuous differences in amino acid composition were not correlated with the Gm type of these antibodies. Hydroxylysine was found in two of the four antibodies, antidextran and antiteichoic acid, and in gammaM- immunoglobulin. No hydroxylysine was found in gammaG- globulins. These findings probably account for discrepancies in the literature concerning the occurrence of this residue in antibody protein.

Alanine↗
PubMed1984

FBJ virus-induced osteosarcoma contains type I, type I trimer, type III as well as type V collagens.

The FBJ osteosarcoma (a virus-induced osteosarcoma named after its discoverers, Finkel, Biskis, and Jinkins) contains an extensive extracellular matrix. Collagens were extracted by digestion with pepsin in dilute acetic acid from tumors grown in lathyritic mice and fractionated by differential salt precipitation, yielding five fractions. Fraction 1 (precipitated at acidic 0.7 M and neutral 2.0 M NaCl) gave rise mainly to alpha 1(III) chain on phosphocellulose column chromatography. The alpha 1(III) chain was identified by its typical behavior on interrupted electrophoresis and analysis of the CNBr-cleaved peptides. The alpha 1(III) chain of the FBJ tumor had a high content of hydroxylysine and neutral saccharide. Fraction 2 (precipitated at acidic 0.7 M and neutral 4.5 M NaCl) yielded alpha 1(I) and alpha 2(I) chains on the phosphocellulose column from which alpha 1(I) was eluted as a broad peak, conceivably reflecting a high content of hydroxylysine and neutral saccharide. Fraction 4 (precipitated at acidic 1.2 M and neutral 4.5 M NaCl) yielded type V collagen, which also featured an exceptionally high content of neutral saccharide (Yamagata, S., et al. (1982) Biochem. Biophys. Res. Commun. 105, 1208-1214). The proportions of type I, type I trimer, type III, and type V collagens extracted by pepsin digestion from FBJ tumor were calculated to be 33, 29, 26, and 12%, respectively. The FBJ tumor is free from invasion by blood vessels, shows no deposition of calcium, and thus has the appearance of cartilage. But type II collagen, a specific gene product of cartilage, could not be identified in any of the fractions analyzed. Contrary to its appearance, collagen type analyses indicate that FBJ osteosarcoma is literally induced from osteogenic cells.

Amino Acids↗
PubMed1975

Basement membranes: structural and biosynthetic considerations.

Basement membranes are extracellular matrices synthesized by a variety of cells including the basal cells of the epidermis; the respiratory, gastrointestinal, and glandular epithelium; the capillary endothelium; the epithelial cells of the glomerulus, the renal tubule, and the lens capsule; and the endothelium of Descemet's membrane. Basement membranes in the mature animal are free of lipids, DNA, and proteoglycans and are composed of dissimilar protein subunits. One of these is a procollagen-like molecule associated with a noncollagenous matrix glycoprotein. The proportion of the latter component varies among basement membranes. These various subunits are stabilized by hydrogen bonds, disulfide bonds, and aldehyde-derived cross-links which are so extensive that they render the basement membranes highly insoluble. Immunochemical studies indicate three distinct antigenic components which correspond to the collagenous moiety, its nonhelical extension, and the matrix glycoprotein. The collagen component of basement membranes, free of the nonhelical extension, is composed of three identical alpha-chains. It is highly rich in hydroxylysine, 3- and 4-hydroxyproline and contains 4 to 8 residues of half-cystine. It contains 38 residues of glucosyl-galactosyl-hydroxylysine per chain and minimal amounts of mannose, glucosamine, and fucose. Newly synthesized basement membrane collagen is secreted in the extracellular space as the precursor molecule "procollagen." This molecule does not undergo conversion to collagen but interacts with the matrix glycoprotein to give rise to the appropriate structure.

Amino Acids↗
PubMed1981

Disorder of collagen metabolism in a patient with osteogenesis imperfecta (lethal type): increased degree of hydroxylation of lysine in collagen types I and III.

Types I, II and III collagen were isolated from calvarium, skin and cartilage from a patient with recessive lethal osteogenesis imperfecta. the distribution of the various collagen types was normal in all three tissues. The alpha-chains were purified by molecular sieve and ion-exchange chromatography and were found to differ from the corresponding alpha-chains of age-matched controls only in that the alpha 1(I), alpha 2 and alpha 1(III) chains contained higher amounts of hydroxylysine with proportionally less lysine. alpha 1(II) was normal. The excess hydroxylysine residues were all glycosylated in the case of alpha 1(I) chains, but only partly so for the alpha 2 chains. Similar observations were made with collagen from fetuses at various stages of development. In these fetuses, however, the increase in the degree of hydroxylation of lysine in alpha 1(I), alpha 2 and alpha 1(III) varied with age, being highest in the youngest fetus. Seen in the context of embryonic development, the collagen of the patient would correspond to that of a fetus younger than 18 weeks, and one could speculate that the defect seen in this patient is the result of a disturbed process of maturation of connective tissue.

Autopsy↗
PubMed1991

Collagen and uronic acid distribution in the human sclera.

In the normal adult eye the content of uronic acid, hydroxyproline, hydroxylysine and proline from different parts of sclera was examined. Scleral samples from the posterior eyeball showed a higher content of uronic acid than the scleral samples from papilla, equator and limbus. Apart from a lower concentration of hydroxyproline in sclera from equator, no major differences in concentration of hydroxyproline, hydroxylysine or proline was found in sclera samples.

Aged↗
PubMed1961

Amino acid composition of some calcified proteins.

Amino-acid analysis shows that the proteins from two calcified tissues, enamel and snail shell, are related to collagen in that they also contain hydroxylysine . The presence of hydroxyproline is suggested but not confirmed. This evidence, together with other recent findings, suggests that hydroxylysine may have an important role in the calcification of each of these otherwise diverse proteins.

Amino Acids↗
PubMed1998

Effects of temperature, salinity, and medium composition on compatible solute accumulation by thermococcus spp

The effects of salinity and growth temperature on the accumulation of intracellular organic solutes were examined by nuclear magnetic resonance spectroscopy (NMR) in Thermococcus litoralis, Thermococcus celer, Thermococcus stetteri, and Thermococcus zilligii (strain AN1). In addition, the effects of growth stage and composition of the medium were studied in T. litoralis. A novel compound identified as beta-galactopyranosyl-5-hydroxylysine was detected in T. litoralis grown on peptone-containing medium. Besides this newly discovered compound, T. litoralis accumulated mannosylglycerate, aspartate, alpha-glutamate, di-myo-inositol-1,1'(3,3')-phosphate, hydroxyproline, and trehalose. The hydroxyproline and beta-galactopyranosyl-5-hydroxylysine were probably derived from peptone, while the trehalose was derived from yeast extract; none of these three compounds was detected in the other Thermococcus strains examined. Di-myo-inositol-1,1'(3,3')-phosphate, aspartate, and mannosylglycerate were detected in T. celer and T. stetteri, and the latter organism also accumulated alpha-glutamate. The only nonmarine species studied, T. zilligii, accumulated very low levels of alpha-glutamate and aspartate. The levels of mannosylglycerate and aspartate increased in T. litoralis, T. celer, and T. stetteri in response to salt stress, while di-myo-inositol-1,1'(3,3')-phosphate was the major intracellular solute at supraoptimal growth temperatures. The phase of growth had a strong influence on the types and levels of compatible solutes in T. litoralis; mannosylglycerate and aspartate were the major solutes during exponential growth, while di-myo-inositol-1,1'(3,3')-phosphate was the predominant organic solute during the stationary phase of growth. This work revealed an unexpected ability of T. litoralis to scavenge suitable components from the medium and to use them as compatible solutes.

Journal Article↗
PubMed1999

Biochemical and ultrastructural changes in rabbit sclera after treatment with 7-methylxanthine, theobromine, acetazolamide, or L-ornithine.

AIMS: To examine a possible effect of 7-methylxanthine, theobromine, acetazolamide, or L-ornithine on the ultrastructure and biochemical composition of rabbit sclera. METHODS: Groups of pigmented rabbits, six in each group, were dosed during 10 weeks with one of the substances under investigation, and one untreated group was the control. Samples of anterior and posterior sclera were taken for determination of hydroxyproline, hydroxylysine, proline, proteoglycans, uronic acids and dermatan sulphate, chondroitin sulphate, and hyaluronic acid. Sections were examined with electron microscopy, and the diameter of the individual collagen fibrils was measured. RESULTS: Treatment with theobromine produced a significant increase in the contents of hydroxylysine, hydroxyproline, and proline in both anterior and posterior sclera, while 7-methylxanthine increased the contents of hydroxyproline and proline selectively in posterior sclera. Acetazolamide, on the other hand, significantly decreased the contents of hydroxyproline and proline in samples from anterior sclera. Uronic acids in both anterior and posterior sclera were significantly reduced by treatment with 7-methylxanthine, and L-ornithine significantly reduced uronic acids in posterior sclera. An inverse correlation between contents of hydroxyproline and uronic acids was found. The mean diameter of collagen fibrils was significantly higher in the posterior sclera from rabbits treated with 7-methylxanthine or theobromine, and significantly lower in rabbits treated with acetazolamide or L-ornithine compared with controls. In the anterior sclera, fibril diameter was significantly reduced in all treatment groups compared with controls. A positive, significant correlation between fibril diameter and content of hydroxyproline and proline was found in posterior sclera. CONCLUSION: 7-Methylxanthine, a metabolite of caffeine, increases collagen concentration and the diameter of collagen fibrils in the posterior sclera, and may be useful for treatment or prevention of conditions associated with low level and/or inferior quality of scleral collagen, such as axial myopia, chronic open angle glaucoma, and possibly neovascular age related macular degeneration. The apparent loss of collagen induced by chronic treatment with acetazolamide should be taken into consideration as a potentially harmful side effect. These results may indicate that scleral biochemistry and ultrastructure are influenced by the retinal pigment epithelium. One possible explanation is that the scleral fibroblasts which produce the collagen are sensitive to changes in the physiological electric field created by the retinal pigment epithelium.

Acetazolamide↗
PubMed1998

Cerebral arteriolar dilations by KATP channel activators need L-lysine or L-arginine.

We investigated the effects of various amino acids on responses to ATP-sensitive potassium (KATP) channel openers in anesthetized cats equipped with cranial windows. The application of pinacidil by superfusion caused transient vasodilation, whereas there was sustained vasodilation from the application of stationary solution of pinacidil. In the presence of L-arginine or L-lysine, pinacidil by superfusion led to sustained vasodilation, suggesting that the rapid flow of fluid displaced these amino acids from binding on the channel and that such binding was essential for opening the channel. NG-nitro-L-arginine blocked responses to pinacidil, and this blockade was reversed by L-lysine or L-arginine but not by D-arginine, D-lysine, methyl-L-arginine, glycine, L-histidine, dimethylarginine, dimethyl-L-arginine, or hydroxylysine. The blockade of responses to pinacidil induced by glyburide was also reversed completely by L-arginine or L-lysine but not by D-arginine, suggesting that these amino acids act on the sulfonylurea receptor. Hydroxylysine but not methyl-L-lysine, dimethylarginine, or dimethyl-L-arginine blocked responses to pinacidil. The findings show that KATP channels in cerebral arterioles need L-lysine or L-arginine to open in response to agonists.

Adenosine Triphosphate↗
PubMed1975

Basement membranes: current concepts of structure and synthesis.

Basement membranes are composed of dissimilar protein subunits. The procollagen-like subunit is associated with noncollagenous matrix glycoproteins. The proportion of the latter components varies among basement membranes. The various subunits interact via hydrogen bonds, disulfide bonds and aldehyde-derived cross-links. The extensive degree of cross-linking renders basement membranes highly insoluble. A procollagen-like molecule, extracted from calf anterior lens capsule, exhibits on electron microscopy a filamentous component with a globular portion attached at one end. Treatment of basement membranes with pepsin at low temperature digests the noncollagenous glycoprotein components and allows the collagenous component to come into solution. Purification of the pepsin-solubilized collagen from basement membranes reveals a molecule composed of three identical alpha-chains. Other unique features include 40-50 residues of hydroxylysine, 128-140 residues of 4-hydroxyproline, 12-15 residues of 3-hydroxyproline, 29 residues of arginine, 35 residues alanine, 2-4 residues of half-cystine, 38 residues of glucosyl-galactosyl-hydroxylysine, 3 residues of mannose, 2 residues of glucosamine, and 0.3 residues of fucose. Immunochemical studies indicate the presence of three distinct antigenic components and support the evidence that one is collagenous and the other two are noncollagenous glycoproteins. One of the latter corresponds to the non-helical extension of procollagen. The other is a large-molecular weight highly cross-linked matrix protein.

Amino Acids↗