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Biomedical subjects

K Murakami

Publications and source records attributed to K Murakami.

At least 1,315 records · Page 73Linked to original sources
PubMed1977

Pure Renin. Isolation from hog kidney and characterization.

The pressor enzyme renin (EC 3.4.99.19) was isolated in a pure and stable form from hog kidney by affinity chromatography on a pepstatin/agarose gel followed by three additional steps of conventional chromatography. Destruction of the enzyme by proteolysis during isolation was prevented by chemically eliminating proteases in extracts. The pure preparation was used for the characterization of this enzyme. Renin was found to be a glycoprotein containing glucosamine and possessing binding affinity to concanavalin A. Contrary to previous reports, pure renin is stable at neutral pH either at 4 or -20 degrees for 3 to 8 weeks. It has a molecular weight of 36,400 as determined by equilibrium ultracentrifugation, an isoelectric point of 5.2 and E1%1cm (280 nm) of 9.1. In contrast to crude preparations, the enzyme activity has a broad pH optimum between pH 5.5 and 7.0 for both hog angiotensinogen and the synthetic octapeptide substrate benzyloxycarbonyl-Pro-Phe-His-Leu-Leu-Val-Tyr-Ser-beta-naphthylamide. The rate of formation of angiotensin I from hog angiotensinogen at pH 6.0 and 37 degrees was 267 microng/h/microng of renin, or 2000 Goldblatt units/mg of renin. For the synthetic fluorogenic octapeptide substrate benzyloxycarbonyl-Pro-Phe-His-Leu-Leu-Val-Tyr-Ser-beta-naphthylamide, a Km of 33 micronM and a Vmax of 0.94 micronmol/h/mg of enzyme were obtained at pH 6.5 and 37 degrees.

Angiotensinogen↗
PubMed1977

Purification of high molecular weight forms of renin from hog kidney.

To elucidate the possible regulatory function of high molecular weight renins in blood pressure control, studies were initiated to purify and characterize the high molecular weight enzyme. To avoid the destructive effect of acidification during affinity chromatographic elution, pepstatin-aminobutyl-agarose gel was used from which renin could be eluted at a neutral pH in 2 M urea. Three additional steps of conventional chromatography after the affinity technique produced two types of high molecular weight renins in electrophoretically homogeneous forms. Big renin with a molecular weight of 61,000 has a specific activity approximately 20% of the fully active small molecular weight renin (mol wt 40,000). Big big renins with molecular weights of 140,000 were discovered and purified in two homogeneous forms with specific activities less than 1% of the fully active renin. The possibility of zymogen-enzyme relationship involving the big big, the big, and the fully small molecular weight renins is discussed.

Angiotensin I↗
PubMed1977

Partial purification of human renin.

An affinity gel for the purification of renin was prepared by coupling pepstatin to aminohexylagarose gel. Partially purified human renin (Haas et al., Arch. Biochem. Biophys., 110, 534-543, 1965) was purified further by affinity chromatography on the pepstatin-aminohexyl-agarose gel, gel filtration on a Sephadex G-75 column, and ion exchange chromatography on a DEAE-cellulose column. Separation from a protease permitted further purification without progressive loss of activity. Three peaks of enzymatically active renin were obtained after the DEAE-cellulose chromatography, with specific activities ranging from 206 to 166 and 85 Goldblatt units/mg protein, respectively. The specific activity of 206 GU units/mg represents a 103,000-fold purification compared to the renin present in the first crude extract.

Chromatography, Affinity↗
PubMed1977

Physiologic role of somatostatin. Insulin release from rat islets treated by somatostatin antiserum.

In order to clarify the physiologic role of somatostatin in insulin release, rat pancreatic islets treated by somatostatin antiserum were incubated in media containing various concentrations of glucose. Insulin release from antiserum-treated islets was significantly elevated above that from nontreated ones at 3.3 and 8.3 mM glucose, while the former was not different from the latter at 16.7 mM glucose. It is suggested that somatostatin plays an important role in the regulation of insulin release in the physiologic range of glucose concentration.

Animals↗