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R Timpl

Publications and source records attributed to R Timpl.

At least 415 records · Page 23Linked to original sources
PubMed1977

Disulfide-linked cyanogen bromide peptides of bovine fibrinogen. II. Isolation and sequence analysis of the chain constituents from the amino terminal region.

Bovine fibrinogen was cleaved with CNBr and the peptide F-CB1 which originates from the amino end of the molecule was purified by chromatographic methods. After reduction and alkylation of F-CB1 three main polypeptide chains could be identified. They were derived from the A alpha chain (F-CB1 alpha), Bbeta chain (F-CB1 beta) and gamma chain (F-CB1 gamma) of fibrinogen and consisted of 54, 143 and 78 amino acid residues, respectively. Thrombin digestion released fibrinopeptide A from F-CB1 alpha and smaller amounts of the peptide Gly-Pro-Arg while fibrinopeptide B was released from F-CB1 beta. Fragment F-CB1 gamma was resistant to thrombin. The sequences of 35 amino acid residues in the portion of F-CB1 alpha adjacent to fibrinopeptide A and of 15 residues in F-CB1 beta beyond fibrinopeptide B were determined. They differ by six and two substitutions, respectively, when compared with the homologous part in human fibrinogen. However, the first 29 amino acid residues in bovine and human F-CB1 gamma were identical. The data show that the cysteine-containing regions and the portions to the right of the site of thrombin cleavage in fibrinogen show much less interspecies variability than that known for the fibrinopeptides.

Amino Acid Sequence↗
PubMed1976

Characterization of the amino-terminal segment in type III procollagen.

Native type III collagen and procollagen were prepared from fetal bovine skin. Examination of the cleavage products produced by digestion with tadpole collagenase demonstrated that the three palpha1(III) chains of type III procollagen were linked together by disulfide bonds occurring at both the amino-terminal and carboxy-terminal portions of the molecule. Type III collagen contained interchain disulfide bonds only in the carboxy-terminal region of the molecule. After digestion of procollagen with bacterial collagenase an amino-terminal, triple-stranded peptide fragment was isolated. The reduced and alkylated chain constituents of this fragment had molecular weights of about 21 000. After digestion of procollagen with cyanogen bromide a related triple-stranded fragment was isolated. The chains of the cyanogen bromide fragment had a molecular weight of about 27 000. When the collagenase-derived peptide was fully reduced and alkylated, it became susceptible to further digestion with bacterial collagenase. This treatment released a fragment of about 97 amino acid residues which contained 12 cystein residues and had an amino acid composition typical for globular proteins. A second, non-helical fragment of about 48 amino acid residues contained three cysteines. This latter fragment is formed from sequences that overlap the amino-terminal region in the collagen alpha1(III) chain by 20 amino acids and possesses an antigenic determinant specific for the alpha1(III) chain. The collagenase-sensitive region exposed by reduction comprised about 33 amino acid residues. It was recovered as a mixture of small peptides. These results indicate that the amino-terminal region of type III procollagen has the same type of structure as the homologous region of type I procollagen. It consists of a globular, a collagen-like and a non-helical domain. Interchain disulfide bonding and the occurrence of cysteines in the non-helical domain are, however, unique for type III procollagen.

Amino Acid Sequence↗
PubMed1976

NH2-terminal extensions on skin collagen from sheep with a genetic defect in conversion of procollagen into collagen.

A modified form of procollagen was extracted with 10 M urea from the skin of lambs with dermatosparaxis, a disease which is produced by a genetic defect in the conversion of procollagen to collagen. The extracts contained little if any alpha1 and alpha2 chains of normal type I collagen, and instead they contained the larger polypeptides palpha1 and palpha2 together with high polymers. palpha1 was purified by ion-exchange chromatography and gel filtration. The polypeptide was shown to be related to alpha1 by its chromatographic behavior, its amino acid composition, and the peptides obtained after cleavage with cyanogen bromide. The molecular weight of palpha1 by gel filtration was 112 300 +/- 6300. After digestion of palpha1 with bacterial collagenase, a fragment of about 100 amino acid residues was obtained which was similar in amino acid composition and antigenic activity to a comparable fragment previously obtained from the NH2-terminal region of palpha1 chains from dermatosparaxic cattle. However, after cleavage of palpha1 with cyanogen bromide, a larger NH2-terminal fragment of about 160 amino acid residues was obtained. The larger cyanogen bromide fragment contained 8 residues of hydroxyproline, 12 residues of proline, and 19 residues of glycine not found in the NH2-terminal fragment isolated after digestion with bacterial collagenase. The results indicated that, in addition to containing amino acid sequences similar to those found in globular proteins, the peptide extensions on the NH2-terminal end of the palpha1 chain of procollagen also contain amino acid sequences similar to those found in the triple-helical region of the collagen molecule. The molecular weight of palpha2 by gel filtration was 102 400 +/- 6800. No additional peptide fragment was recovered after digestion of palpha2 with bacterial collagenase.

Amino Acids↗
PubMed1976

Disulfide-linked cyanogen bromide peptides of bovine fibrinogen. I. Isolation of peptide F-CB3 and characterization of its single disulfide bond by cleavage with cyanide.

A fragment F-CB3 which originates from the alpha-chain constituent of bovine fibrinogen could be liberated by CNBr cleavage and was purified by molecular sieve and ion-exchange chromatography. This fragment had a molecular weight of 36 000 and consisted of a single polypeptide chain which is folded into a loop by a single disulfide bridge. Further cleavage of F-CB3 by cyanide or by 2-nitro-5-thiocyanobenzoic acid gave rise to three fragments, CN1, CN2 and CN3, with molecular weights of 23 000, 8000 and 7000, respectively. With both reagents the yield of cleavage did not exceed 50%. Radioactive labeling and amino acid analysis of the purified fragments indicated the order CN1-CN2-CN3 in intact F-CB3. A shorter and apparently degraded form of F-CB3 was observed in some fibrinogen preparations. The shortening involved a region of about 3000 daltons at the N-terminal site of F-CB3, i.e. in fragment CN1.

Amino Acids↗
PubMed1976

Preparation and use in immunohistology of antibodies specific for type I and type III collagen and procollagen.

Antibodies to bovine type I and type III collagen and their precursor form procollagen were produced in rabbits and rendered specific for the immunizing antigen by immunoadsorption. These purified antibodies showed distinct immunofluorescence staining on frozen sections of both bovine and human connective tissue at concentrations as low as 1-10 mug/ml. Antibodies to type III collagen and procollagen reacted with reticulin in liver and spleen, with fascicles around tendons and with the upper portion of the dermis. Antibodies to type I collagen and procollagen reacted with skin and fiber bundles in tendon but did not stain reticulin. No reaction was observed with cartilage collagen or with kidney glomerular basement membrane.

Animals↗
PubMed1976

Radioimmunoassay for the aminoterminal peptide of procollagen p alpha 1(I)-chain.

Peptides derived from the aminoterminal portion of the palpha1(I)-chain of calf and sheep procollagen were labeled with iodine-125. Despite changes in electrophoretic homogeneity after labeling, reaction of the labeled peptide with antisera to unlabeled peptide was retained. Antisera to procollagen or the isolated procollagen peptide showed high titers for the native peptide, a much weaker binding with the reduced and alkylated peptide and little or no reaction with collagen. Antisera to collagen showed strong binding with collagen and a weaker but distinct reaction with the procollagen peptide. Evidence was obtained that a minor contaminant of procollagen peptide was present in the acid-extracted collagen and that there were no shared antigenic determinants. Bovine serum and amniotic fluid contained 1-10 mug/ml reactive antigen. These results indicate that the labeled peptides can be used as a specific, sensitive and accurate assay for the amino-terminal portion of procollagen in biological samples.

Animals↗