Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.11.2 (prolyl hydroxylase)
 1,814 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The formation of 3-hydroxyproline was studied with crude rat kidney cortex extract as a source of enzyme and chick embryo tendon protocollagen and procollagen or cartilage protocollagen as a substrate. Synthesis of 3-hydroxyproline was observed with all these substrates and the formation of 3-hydroxyproline ranged up to seven residues per pro-alpha-chain. The highest rate of 3-hydroxylation took place at 20 degrees C and the reaction required Fe2+, O2,2-oxoglutarate and ascorbate. The formation of 3-hydroxyproline was affected by chain length and the conformation of the substrate, in that longer polypeptide chains proved better substrates, while the native triple-helical conformation of protocollagen or procollagen completely prevented the reaction. Formation of 3-hydroxyproline with tendon procollagen as a substrate was not inhibited by antiserum to prolyl 4-hydroxylase or by poly(L-proline) when these substances were used in concentrations which clearly inhibited 4-hydroxyproline formation with tendon protocollagen as a substrate. Furthermore, pure prolyl 4-hydroxylase did not synthesize any 3-hydroxyproline under conditions in which the crude rat kidney cortex enzyme would readily do so. The data thus strongly suggest that prolyl 3-hydroxylase and prolyl 4-hydroxylase are separate enzymes.
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PMID:Prolyl 3-hydroxylase: partial characterization of the enzyme from rat kidney cortex. 19 Dec 55

Fibroblasts isolated by enzymic digestion of chick embryo tendons have previously been used to examine the kinetics for the secretion of procollagen (Kao, W. W.-Y., Berg, R. A., and Prockop, D. J. (1977) J. Biol. Chem. 252, 8391-8397). The results indicated that the kinetics approximated the sum of two first order processes with half-times of 14 and 115 min. Here, the same fibroblasts were incubated in the presence of 1.53 mM cis-4-hydroxyproline, an analogue of proline, or in the presence of 0.3 mM alpha,alpha'-dipyridyl, an inhibitor of prolyl hydroxylase, so that the cells synthesized procollagen which could not assume a triple helical conformation characteristic of procollagen. Measurements of the secretion of nonhelical procollagen indicated that the kinetics for secretion differed from the kinetics for the secretion of procollagen and approximated a single first order process with a half-time of approximately 130 min. The nonhelical procollagen synthesized and secreted in the presence of either cis-4-hydroxyproline or alpha,alpha'-dipyridyl consisted of disulfide-bonded pro gamma chains of type I procollagen. The results suggested that the intracellular nonhelical procollagen was present in a single metabolic pool and secretion from this pool occurred with a different rate-limiting step than for helical procollagen. Further results indicated that nonhelical procollagen had a high affinity for prolyl hydroxylase and the affinity for the enzyme was greatly reduced if the procollagen was allowed to assume the triple helical conformation characteristic of normal procollagen. The results are consistent with the hypothesis that the secretion of procollagen is influenced by its conformation-dependent interaction with prolyl hydroxylase or other post-translational enzymes.
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PMID:Kinetics for the secretion of nonhelical procollagen by freshly isolated tendon cells. 57 Sep 70

Prolyl 4-hydroxylase (EC 1.14.11.2), an alpha 2 beta 2 tetramer, catalyzes the posttranslational formation of 4-hydroxyproline in collagens. The enzyme can easily be dissociated into its subunits, but all attempts to associate a tetramer from the dissociated subunits in vitro have been unsuccessful. Molecular cloning of the catalytically important alpha subunit has identified two types of cDNA clone due to mutually exclusive alternative splicing. The beta subunit is a highly unusual multifunctional polypeptide, being identical to the enzyme protein disulfide-isomerase (EC 5.3.4.1). We report here on expression of the alpha and beta subunits of prolyl 4-hydroxylase and a fully active enzyme tetramer in Spodoptera frugiperda insect cells by baculovirus vectors. When the beta subunit was expressed alone, the polypeptide produced was found in a 0.1% Triton X-100 extract of the cell homogenate and was a fully active protein disulfide-isomerase. When either form of the alpha subunit was expressed alone, only traces of the alpha subunit could be extracted from the cell homogenate with 0.1% Triton X-100, and 1% SDS was required to obtain efficient solubilization. These alpha subunits had no prolyl 4-hydroxylase activity. When the cells were coinfected with both alpha- and beta-subunit-producing viruses, an enzyme tetramer was formed, but significant amounts of alpha and beta subunits remained unassociated. The recombinant tetramer was indistinguishable from that isolated from vertebrate tissue in terms of its specific activity and kinetic constants for cosubstrates and the peptide substrate. The two alternatively spliced forms of the alpha subunit gave enzyme tetramers with identical catalytic properties. Baculovirus expression seems to be an excellent system for mass production of the enzyme tetramer and for detailed investigation of the mechanisms involved in the association of the monomers.
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PMID:Characterization of the human prolyl 4-hydroxylase tetramer and its multifunctional protein disulfide-isomerase subunit synthesized in a baculovirus expression system. 132 38

Prolyl 4-hydroxylase, an alpha 2 beta 2 tetramer, catalyzes the formation of 4-hydroxyproline in collagens and related proteins by hydroxylating proline residues in peptide linkages. The beta-subunit of prolyl 4-hydroxylase (P4HB) is a highly unusual multifunctional polypeptide that is identical to the enzyme protein disulfide isomerase and a major cellular thyroid hormone-binding protein and is highly similar to a glycosylation site-binding polypeptide of oligosaccharyl transferase. We report here the regional assignment of the gene for this multifunctional polypeptide. In situ hybridization mapped the gene to 17q25. Southern blot analyses of restricted DNA from a chromosome-mediated gene transfer transfectant panel suggested that the P4HB gene is located distal to the gene for thymidine kinase, either between the genes for thymidine kinase and galactokinase or on the telomeric side of both these genes.
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PMID:Regional assignment of the human gene coding for a multifunctional polypeptide (P4HB) acting as the beta-subunit of prolyl 4-hydroxylase and the enzyme protein disulfide isomerase to 17q25. 164 89

Excessive accumulation of collagen in the extracellular matrix has a crucial role in fibrosis. Thus pharmacological inhibition of collagen deposition is likely to be beneficial for patients suffering from fibrotic disorders such as liver cirrhosis. Prolyl 4-hydroxylase catalyzes the formation of 4-hydroxyproline in collagens and other proteins with collagen-like amino acid sequences by the hydroxylation of proline residues in -X-Pro-Gly- sequences. The reaction products, 4-hydroxyproline residues, serve to stabilize the collagen triple helices under physiological conditions. Conversely, collagen chains that contain no 4-hydroxyproline cannot fold into triple helical molecules that are stable at body temperature. The prolyl 4-hydroxylase reaction therefore seems to be a particularly suitable target for the pharmological regulation of excessive collagen formation. The reaction catalyzed by prolyl 4-hydroxylase requires Fe2+, 2-oxoglutarate, O2 and ascorbate and involves an oxidative decarboxylation of 2-oxoglutarate. The active enzyme is an alpha 2 beta 2 tetramer that consists of two types of inactive monomer and has two catalytic sites. Some parts of the catalytic sites may be built up cooperatively of both the alpha and beta subunits, but the alpha subunit appears to contribute the major part. The beta subunit contains the carboxyl-terminal tetrapeptide sequence -Lys-Asp-Glu-Leu which is essential for the retention of a polypeptide within the lumen of the endoplasmic reticulum. Since the alpha subunit lacks the carboxyl-terminal retention signal, one function of the beta subunit in the prolyl 4-hydroxylase tetramer may be to retain the enzyme within the endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prolyl 4-hydroxylase and its role in collagen synthesis. 166 65

The crucial role of collagen in fibrotic disorders has prompted attempts to develop drugs that inhibit collagen accumulation. Peptides containing the unphysiological amino acid 5-oxaproline (Opr) have recently been found to act as specific syncatalytic inactivators of pure prolyl 4-hydroxylase, the enzyme that catalyzes the formation of 4-hydroxyproline in collagens. The present study indicates that oxaproline-containing peptides benzyloxycarbonyl-Phe-Opr-Gly-benzyl ester (I) and benzyloxycarbonyl-Phe-Opr-Gly-ethyl ester (II) inactivate prolyl 4-hydroxylase in cultured human skin fibroblasts, peptide I being about twice as potent as peptide II. Inactivation by 50% was observed after culturing with about 20-40 microM concentrations of peptide I for 48 h. The inactivation appears to be specific, as no changes were found in the activities of two other intracellular enzymes of collagen synthesis, lysyl hydroxylase and galactosylhydroxylysyl glucosyltransferase. Synthesis of 4-hydroxyproline by the cells was markedly decreased, and 4-hydroxyproline-deficient procollagen accumulated intracellularly, whereas no changes were found in the incorporation of [14C]leucine into protein after culturing of the cells with a 30 microM concentration of peptide I for 48 h. No changes were seen in the viability of the cells or the release of lactate dehydrogenase from them into the culture medium. No significant changes were found in the steady-state levels of the mRNAs for the pro-alpha 1 chains of type I and type III procollagens or for the alpha and beta subunits of prolyl 4-hyroxylase or fibronectin after culturing with 75 microM peptide I for 48 h. The data indicate that inactivation of cellular prolyl 4-hydroxylase has marked effects on cellular 4-hydroxyproline formation and collagen secretion but no effects on the steady-state levels of mRNAs for type I and III procollagens or the two types of subunit of prolyl 4-hydroxylase.
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PMID:Specific inactivation of prolyl 4-hydroxylase and inhibition of collagen synthesis by oxaproline-containing peptides in cultured human skin fibroblasts. 216 Apr 57

The activities of three enzymes concerned with collagen metabolism 4-prolyl hydroxylase, UDP-glucose: collagen glucosyltransferase and glucosyl-galactosyl-hydroxylysine glucohydrolase and 4-hydroxyproline content have been studied in the cardiac ventricles of spontaneously hypertensive rats (SHR) during prehypertensive, hypertensive and sustained hypertensive stages (respectively 4.5, 12 and 19 weeks of age). They were compared with values observed in age-matched normotensive Wistar Kyoto rats (WKY). The same studies have been performed in parallel on aortic-constricted rats (ACR) 8 days after suprarenal constriction of the abdominal aorta. The most striking finding was a significant increase in cardiac prolyl hydroxylase specific activity in the ACR but not in the SHR. No variation in 4-hydroxyproline concentration was found in the hearts of ACR. In contrast, a decrease in 4-hydroxyproline concentration was found in the hearts of SHR at 19 weeks. Cardiac glucosyltransferase specific activity was significantly elevated only in the SHR at 12 weeks. No variation in glucohydrolase specific activity was detected in the hearts of either SHR or ACR. The cardiac enzyme activities all decreased with age. These data show that the alterations in cardiac collagen metabolism are different in SHR and ACR. The patterns of the alterations found in the heart mirror those observed in the aorta in both models under the same experimental conditions.
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PMID:Modification of enzyme activities concerned with collagen metabolism in the heart of spontaneously hypertensive and aortic-constricted rats. 252 11

Prolyl 4-hydroxylase (EC 1.14.11.2) catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in X-Pro-Gly sequences. The reaction requires Fe2+, 2-oxoglutarate, O2, and ascorbate and involves an oxidative decarboxylation of 2-oxoglutarate. Ascorbate is not consumed during most catalytic cycles, but the enzyme also catalyzes decarboxylation of 2-oxoglutarate without subsequent hydroxylation, and ascorbate is required as a specific alternative oxygen acceptor in such uncoupled reaction cycles. A number of compounds inhibit prolyl 4-hydroxylase competitively with respect to some of its cosubstrates or the peptide substrate, and recently many suicide inactivators have also been described. Such inhibitors and inactivators are of considerable interest, because the prolyl 4-hydroxylase reaction would seem a particularly suitable target for chemical regulation of the excessive collagen formation found in patients with various fibrotic diseases. The active prolyl 4-hydroxylase is an alpha 2 beta 2 tetramer, consisting of two different types of inactive monomer and probably containing two catalytic sites per tetramer. The large catalytic site may be cooperatively built up of both the alpha and beta subunits, but the alpha subunit appears to contribute the major part. The beta subunit has been found to be identical to the enzyme protein disulfide isomerase and a major cellular thyroid hormone-binding protein and shows partial homology with a phosphoinositide-specific phospholipase C, thioredoxins, and the estrogen-binding domain of the estrogen receptor. The COOH-terminus of this beta subunit has the amino acid sequence Lys-Asp-Glu-Leu, which was recently suggested to be necessary for the retention of a polypeptide within the lumen of the endoplasmic reticulum. The alpha subunit does not have this COOH-terminal sequence, and thus one function of the beta subunit in the prolyl 4-hydroxylase tetramer appears to be to retain the enzyme within this cell organelle.
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PMID:Protein hydroxylation: prolyl 4-hydroxylase, an enzyme with four cosubstrates and a multifunctional subunit. 253 73

Prolyl 4-hydroxylase [procollagen-proline, 2-oxyglutarate 4-dioxygenase; procollagen-L-proline, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2], an alpha 2 beta 2 tetramer, catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in peptide linkages. We report here on the isolation of cDNA clones encoding the alpha-subunit of the enzyme from human tumor HT-1080, placenta, and fibroblast cDNA libraries. Eight overlapping clones covering almost all of the corresponding 3000-nucleotide mRNA, including all the coding sequences, were characterized. These clones encode a polypeptide of 517 amino acid residues and a signal peptide of 17 amino acids. Previous characterization of cDNA clones for the beta-subunit of prolyl 4-hydroxylase has indicated that its C terminus has the amino acid sequence Lys-Asp-Glu-Leu, which, it has been suggested, is necessary for the retention of a polypeptide within the lumen of the endoplasmic reticulum. The alpha-subunit does not have this C-terminal sequence, and thus one function of the beta-subunit in the prolyl 4-hydroxylase tetramer appears to be to retain the enzyme within this cell organelle. Interestingly, three of the cDNA clones for the alpha-subunit contained a 64-nucleotide sequence homologous but not identical to the corresponding 64-nucleotide sequence found in four other cDNA clones. Nuclease S1 mapping experiments demonstrated that this difference was due to the existence of two types of mRNA present in approximately equal amounts. Southern blot analyses of human genomic DNA with a cDNA probe for the alpha-subunit suggested the presence of only one gene encoding the two types of mRNA, which appear to result from mutually exclusive alternative splicing of primary transcripts of one gene.
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PMID:Molecular cloning of the alpha-subunit of human prolyl 4-hydroxylase: the complete cDNA-derived amino acid sequence and evidence for alternative splicing of RNA transcripts. 254 75

Prolyl 4-hydroxylase, an alpha 2 beta 2 tetramer, catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in peptide linkages and plays a crucial role in the synthesis of these proteins. The gene for the beta-subunit of prolyl 4-hydroxylase has recently been mapped to the long arm of human chromosome 17, at band 17q25. We report here chromosomal localization of the gene for the catalytically and regulatorily important alpha-subunit of human prolyl 4-hydroxylase. Analysis of 24 rodent x human cell hybrids by Southern blotting with cDNA probes for the human alpha-subunit indicated complete cosegregation of the gene for the alpha-subunit with human chromosome 10. A cell hybrid containing only part of chromosome 10 mapped the gene to 10q11----qter. In situ hybridization mapped the gene to 10q21.3-23.1. The gene for the alpha-subunit is thus not physically linked to that for the beta-subunit of the enzyme.
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PMID:Assignment of the gene coding for the alpha-subunit of prolyl 4-hydroxylase to human chromosome region 10q21.3-23.1. 255 27


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