Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A process for conformational modification of protein, which we have previously reported, was investigated as a means of generating fluorohydrolase activity in bovine ribonuclease (RNase). The resulting modified RNase had catalytic activity that depended upon the chosen modifier. Bovine pancreatic ribonuclease, modified by addition of hexamethylphosphoramide (HMPA) at pH 3, was derivatized with diimidates of chain lengths from C1 to C8. The derivative with the highest activity was obtained when RNase was crosslinked with dimethyl pimelimidate (C5). This derivative, which was active over a pH range of 6.5 to 8.0 with an optimum pH of 7.4, hydrolyzed phenylmethylsulfonylfluoride (PMSF) and the potent acetylcholinesterase inhibitor, diisopropyl phosphorofluoridate (DFP). The mean fluorohydrolase activity for four preparations using dimethyl pimelimidate was 0.8 +/- 0.2 U mg-1. Gel filtration on G-75 Sephadex and SDS-polyacrylamide gel electrophoresis showed components having a molecular weight of 13,000 and 27,000, with activity restricted to the 27,000 molecular weight fraction. After gel filtration, the specific activity was 9.1 +/- 2.4 U mg-1, resulting in a molecular activity of 125 min-1. The mechanism of this unique transformation of RNase into a fluorohydrolase is not known, nor has the location of the active site been determined.
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PMID:Semisynthetic fluorohydrolases prepared by chemical modification of ribonuclease. 136 89

Generation of a cytoplasmic factor(s) that induced IgG secretion in nonstimulated cells was demonstrated in TRF-stimulated cells by using red cell-mediated microinjection. Injection of the cytoplasm from a TRF-stimulated B lymphoblastoid cell line (CESS) into nonstimulated cells induced an increase of IgG-producing cells. Injection of TRF itself did not induce an increase of IgG-producing cells. Active substance(s) in the cytoplasm were generated at 2 hr after TRF stimulation, and IgG-producing cells reached their maximum level at 40 hr after injection of the factor(s). DFP, but not actinomycin D, inhibited the generation of the cytoplasmic factor(s). The activity of the cytoplasmic factor(s) was not destroyed by RNase and not absorbed with anti-IgG. These results suggested that binding of TRF with its acceptors induced the generation of the cytoplasmic factor(s) involved in the transmission of TRF-mediated signals from membrane to nuclei.
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PMID:IgG induction in a human B cell line by red cell-mediated microinjection of the cytoplasm from T cell factor-stimulated B cells. 698 Sep 30

Cathepsin A was purified approximately 550-fold with an overall yield of 4% from bovine spleen crude extracts by successive chromatographies on DEAE-Sephadex A-50, phenyl-Toyopearl 650C, and Con A-agarose. PAGE of the purified enzyme without 2-mercaptoethanol revealed an apparent molecular size of 110 kDa, and SDS-PAGE with 2-mercaptoethanol gave two polypeptide bands corresponding to 32 and 25 kDa and without 2-mercaptoethanol a single polypeptide 52 kDa band. These results indicate that the enzyme has an (alpha beta)2 tetrameric structure in which the alpha (32 kDa) and beta (25 kDa) subunits are linked by disulfide bond(s). The enzyme exhibited peptidase activities, hydrolyzing various Z-dipeptides with optimum pHs between 5.0 and 5.8. The hydrolytic rate for Z-Phe-Ala was 15 times higher than that for Z-Glu-Tyr, the traditional cathepsin A substrate. The enzyme also catalyzed the hydrolysis of the C-terminal amino acids of RCM-RNase A and showed esterase activity toward BTEE at pH around 7.5. DFP and TPCK completely inhibited both peptidase and esterase activities, and [1,3-3H]DFP was bound to the alpha subunit. All these results support the fact that the enzyme is a serine carboxypeptidase. The N-terminal amino acid sequences of the alpha and beta subunits are highly homologous to those of the human protective protein in galactosialidosis, strongly supporting the identity between cathepsin A and the protective protein.
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PMID:Bovine spleen cathepsin A: characterization and comparison with the protective protein. 953 64