Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human growth hormone B can be converted to its more acidic isohormones C, D, and E by limited enzymatic cleavage with purified plasmin in vitro. This process is accompanied by an increase of biological activity in the rat tibia line assay. A possible role of endogenous circulating plasmin in the in vivo formation of these isohormones was investigated. Human plasma, serum, glass-contact-activated serum, and serum extracts after the removal of protease inhibitors were incubated with ratioiodinated hGH-B and C for up to 24 h. Aliquots were analyzed at frequent intervals by polyacrylamide gel electrophoresis, followed by autoradiography and counting of radioactive bands. No evidence for interconversion or transformation to hGH-D and E was found. It is concluded that endogenous circulating plasmin does not play a major role in the conversion of hGH to its "activated" isohormones.
 ...
PMID:Failure of endogenous plasmin to convert human growth hormone to its "activated" isohormones. 13 16

Reduced and S-carbamidomethylated human GH (RCAM-hGH) was digested with human plasmin, yielding a mixture of products. These were partially separated by chromatography on DEAE-cellulose, yielding three major fractions: Da and Db, which were equipotent with native hGH in the weight gain test; and Dc, which was about half as active as hGH. Each of these was further purified by gel filtration, yielding a number of subfractions which were characterized as follows: Da1 is a very stable noncovalent complex of residues 1--134 and 141--191 of RCAM-hGH; Da2 represents residues 20--41; Db1 is very similar to Da1, but appears to have lost one or more amide groups; Db3 represents residues 95--134; Dc2 is a heterogenous fraction containing a further deamidated version of Da1 and Db1 plus a similar complex of residues 42--134 and 141--191, apparently with some carboxyterminal heterogeneity; Dc3, like Db3, represents residues 95--134. The biological activities of these fragments are discussed in the accompanying paper. Earlier work has shown that native hGH, upon digestion with plasmin, is cleaved primarily at residues 134 and 140. It is shown here that when RCAM-hGH is digested with plasmin, in about 87% of the molecules at least one cleavage takes place in addition to those at residues 134 and 140.
 ...
PMID:Isolation and characterization of fragments of reduced and S-carbamidomethylated human growth hormone produced by plasmin digestion. I. Chemistry. 15

Complementation of the plasmin fragments of reduced-carbamoylmethylated (Cam) human somatotropin (hGH) with those of reduced-carbamoylmethylated human chorionic somatomammotropin (hCS) have been investigated. It was found that the recombinant obtained by noncovalent interaction of [Cys(Cam)53]hGH-(1-134) with [Cys(Cam)-165,182,189]hCS-(141-191) exhibits 50% growth-promoting activity and nearly full immunoreactivity. Complementation of [Cys(Cam)53]hCS-(1-133) with the COOH-terminal fragment of hGH generated lower growth-promoting and immunological activities.
 ...
PMID:Noncovalent interaction of the NH2-terminal fragment of human somatotropin with the COOH-terminal fragment of human choriomammotropin to generate growth-promoting activity. 27

The binding of intact (i) and cleaved (c) 125I-labeled human GH to the hepatic GH-binding sites and to the plasma GH-binding protein (GH-BP) of rabbits was compared. The c-hGH label was prepared by incubation of the iodinated hormone with the plasmalemal fraction of pregnant rat liver. Unlabeled c-hGH was prepared in milligram quantities by digestion with plasmin. The c-hGH label revealed both high and low affinity binding sites on the rabbit liver membranes when it was displaced by unlabeled c-hGH. Cleavage of the hGH label caused a substantial decrease in its affinity for the low affinity site. When i-hGH was used to displace either i-hGH or c-hGH tracers, it failed to discriminate between the two classes of binding sites, as it had equally high affinity for both. The c-hGH had a substantilly lower affinity for the plasma GH-BP than did the i-hGH. This difference is consistent with the c-hGH having an increased bioactivity, but not with its reported slow clearance rate. If cleavage of GH occurs at its sites of action, the lowered affinity for the plasma GH-BP, with retention of high affinity for the high affinity site, could increase its potency relative to that of the i-hGH.
 ...
PMID:Binding of intact and cleaved human growth hormone to hepatic receptors and plasma binding proteins. 153 65

Proteolytically cleaved human 22 kDa growth hormone (22K hGH) between the amino acid residues 134 and 150 by plasmin or other proteases in vitro has been reported to be most active in growth promoting activity. In this study a deleted mutant hGH lacking amino acid residues from 135 to 146 and having more sensitivity to plasmin digestion was produced using the inverse polymerase chain reaction method and the Escherichia coli expression system. The mutant, hGH delta 135-146, was folded and purified effectively and found to be more sensitive to plasmin cleavage to form the two-chain form in vitro. The biological activities of this plasmin sensitive hGH delta 135-146 were tested by in vitro cell proliferation assays and in vivo growth promoting assay. In Ba/F3-hGHR cells, which express receptors for hGH, hGH delta 135-146 showed 10-20% less growth promoting activity than 22K hGH, but expressed comparable quantities of IGF-I mRNA to that of 22K hGH. In Nb2 rat lymphoma cells, which proliferate in response to hGH via the lactogenic receptors, hGH delta 135-146 showed equivalent activities to those of 22K hGH at lower concentrations. By the body weight gain test using hypophysectomized rats, a lower dose (2.5 nmol kg-1) of hGH delta 135-146 exhibited an equivalent activity to that of wild type 22K hGH, but a higher dose (25 nmol kg-1) of the mutant showed less growth promoting activity than 22K hGH. These results indicated that the plasmin sensitive recombinant hGH delta 135-146 failed to show higher biological activity than the 22K hGH in vivo, suggesting the unsuccessful formation of the active two-chain form in vivo.
 ...
PMID:Synthesis and purification of a deleted human growth hormone, hGH delta 135-146: sensitivity to plasmin cleavage and in vitro and in vivo bioactivities. 1070 10