Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The DNA polymerase in crude extracts of Drosophila melanogaster embryos sedimented at 9.0, 7.3, and 5.5 S on glycerol velocity gradients. The relative proportions of these enzymes depended on the method used to prepare the extract. Extracts of whole embryos contained the 7.3S and the 5.5S DNA polymerases and extracts of dechorionated embryos contained the 9.0S and 7.3S DNA polymerases. The porportion of the 5.5S DNA polymerase increased relative to the 7.3S DNA polymerase during storage of the extract of whole embryos. The protease inhibitor, phenylmethanesulfonyl fluoride, inhibited the formation of the 5.5S DNA polymerase, suggesting that it was proteolytically produced from the 7.3S DNA polymerase. This was demonstrated directly by converting the 7.3S DNA polymerase to the 5.5S DNA polymerase by treatment in vitro with trypsin. The degradation of the enzyme occurred without significant loss of DNA polymerase activity. It is further demonstrated that endogenous proteolysis reduced the chromatographic heterogeneity of the Drosophila DNA polymerase on diethylaminoethyl-Sephadex. When endogenous proteolysis was reduced, three forms of DNA polymerase were isolated by diethylaminoethylcellulose chromatography; two of these enzymes sedimented at 7.3S and the third sedimented at 9.0S. These results demonstrate the physical heterogeneity of the Drosophila DNA polymerase and suggest its similarity to vertebrate DNA polymerase-alpha.
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PMID:Multiple forms of Drosophila embryo DNA polymerase: evidence for proteolytic conversion. 40 23

Activity of DNA alpha-polymerase in extracts from MOPC-104E was not associated with a single protein molecule, but with several molecular species that differed in isoelectric point. The three most abundant of these enzyme species were first separated from other DNA polymerases and then resolved from each other by repeated chromatography on diethylaminoethylcellulose columns. Next, with the use of glycerol gradient centrifugation and DNA-cellulose column chromatography, the three species were further purified to a state representing more than 5000-fold purification over the crude extract. These three highly purified enzyme species exhibited very similar catalytic properties, and the main activity of each species sedimented at the same rate (6-7S) in glycerol gradients containing 0.5 M KCl. Analysis of the polypeptide content of each species revealed that polypeptides of about 150 000 and 60 000 daltons cofractionated with the DNA polymerase activity. The multiple alpha-polymerase species did not appear to result from in vitro proteolytic cleavage, since multiple species were observed in extracts prepared under several different types of conditions, including the presence of the protease inhibitors, phenylmethanesulfonyl fluoride, or trasylol. The three species were recovered in about the same relative amounts from both the nuclear and cytoplasmic fractions of MOPC-104E, and it appeared that multiple species of alpha-polymerase were also present in extracts from fetal bovine liver.
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PMID:Studies on DNA alpha-polymerase of mouse myeloma: partial purification and comparison of three molecular forms of the enzyme. 99 8

The effect of alpha-1-antichymotrypsin (ACT), which is known as an efficient serum protease inhibitor and is detected in tumor cell nuclei, on DNA synthesis was studied. ACT inhibited the activity of DNA polymerase alpha purified from human stomach adenocarcinoma. Other human serum proteins including serum albumin, alpha-1-acidglycoprotein, alpha-1-antitrypsin, and immunoglobulin G, as well as other protease inhibitors, such as leupeptin, pepstatin, PMSF and chymostatin, did not affect the activity of DNA polymerase alpha. It was therefore concluded that the inhibitory action of ACT on DNA polymerase alpha was direct phenomenon unrelated to its protease inhibitory activity. Furthermore, the effect of ACT on DNA synthesis was also studied using lysolecithin-permeabilized cultured human stomach carcinoma cells. ACT added in the medium inhibited DNA synthesis and the degree of inhibition depended on incubation time. It was proportional to ACT concentration and the concentration of ACT required for 50% inhibition was 0.8 mg/ml.
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PMID:Inhibition of DNA synthesis by alpha-1-antichymotrypsin. 327 75