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Prolyl 4-hydroxylase (EC, an alpha 2 beta 2 tetramer, catalyses the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in peptide linkages. We report here the isolation of cDNA clones coding for the beta-subunit of prolyl 4-hydroxylase from a human hepatoma lambda gt11 library and a corresponding human placenta(More)
The assembly of reduced pro-alpha chains of type I and type II procollagen into the native triple-helical molecule was examined in vitro in the presence and absence of pure protein disulfide isomerase. The data clearly indicates that protein disulfide isomerase is able to accelerate the formation of native interchain disulfide bonds in these procollagens.(More)
A single polypeptide is shown to act both as the beta subunit of the proline hydroxylase (EC and as a protein disulfide-isomerase (EC When isolated from chick embryos or rat liver, the beta subunit of prolyl 4-hydroxylase and the enzyme protein disulfide-isomerase have identical molecular weights and peptide maps as produced by(More)
Protein disulfide-isomerase was isolated as a homogeneous protein from 15-day-old chick embryos. The enzyme has a molecular weight of 56,000 in SDS-polyacrylamide gel electrophoresis. Its Km value for randomly cross-linked ribonuclease, a protein used as a substrate for the enzyme, was 0.3 microM, and the Km value for DTT was 1.0 microM. Its optimum pH was(More)
A high correlation was found between the activities of protein disulphide isomerase and prolyl 4-hydroxylase when assayed in cells synthesizing various collagen types or the same type at markedly different rates. The highest activities of both enzymes were found in freshly isolated chick-embryo tendon and cartilage cells, intermediate activities in(More)
A two-step procedure is described for the purification of protein disulphide-isomerase (PDI). This procedure is based on the previous finding that the beta-subunit of the prolyl 4-hydroxylase tetramer (alpha 2 beta 2) is identical with PDI [Koivu, Myllylä, Helaakoski, Pihlajaniemi, Tasanen & Kivirikko (1987) J. Biol. Chem. 262, 6447-6449; Pihlajaniemi,(More)
Procollagen molecules have amino-terminal and carboxy-terminal propeptides at the respective ends of the collagenous triple helix. The carboxy-terminal propeptides enhance and direct the association of pro alpha-chains into procollagen molecules, but the mechanism of this registration function is still obscure. A hypothesis concerning the function of(More)
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