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Biomedical subjects

M Morikawa

Publications and source records attributed to M Morikawa.

12 recordsLinked to original sources
PubMed1979

Hydrolysis of ester-type drugs by the purified esterase from human intestinal mucosa.

Esterase from human intestinal mucosa was purified 210 fold by solubilization with Triton X-100, chromatography on DEAE-cellulose, Sephadex G-100 and hydroxylapatite, and isoelectric focusing. The purified esterase showed a single band by polyacrylamide gel electrophoresis. The molecular weight of the purified esterase was estimated to be about 55,000 by gel filtration on Sephadex G-150, and the isoelectric point was 5.02. The purified esterase was strongly inhibited by diethyl p-nitrophenyl phosphate (E-600) and diisopropyl fluorophosphate (DFP), and was not inhibited by eserine sulfate and p-chloromercuribenzoate. The purified esterase from human intestinal mucosa was found to be one of the carboxylesterases. The purified esterase hydrolyzed ester-type drugs, i.e., aspirin, clofibrate, indanyl carbenicillin and procaine, but did not hydrolyze amide-type drugs and choline-type drugs.

Aspirin↗
PubMed1979

Species difference and characterization of intestinal esterase on the hydrolizing activity of ester-type drugs.

The ability of the esterase from intestine was studied for hydrolysis of ester-type drugs during absorption. The intestinal esterase is present in the absorption sites in the intestine and hydrolyzes to a large extent during the absorption. In a study of the dietary effect on intestinal esterase, the esterase activity increased in rats fed a high-fat diet, decreased in those fasted or fed a fat-free diet, whereas the esterase activity in the rat treated with phenobarbital showed no marked change. Thus the esterase from intestinal mucosa appears to be characteristically quite different from hepatic esterase. The esterase from human intestine was characterized and compared with esterase from rats, mice, rabbits, guinea pigs and dogs. There was a difference in the substrate specificity of the esterase and there were significant species differences in the electrophoretic behavior of the enzyme among the species tested. These results indicate that intestinal esterase from humans differs characteristically from esterases in experimental animals.

Animals↗
PubMed1978

Inhibition of yeast phosphatidic-acid synthesis by free fatty acids.

Particulate preparations obtained from cells of yeast Saccharomyces sake have been shown to possess glycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase activities. Glycerolphosphate acyltransferase exhibits a high specificity for saturated and monoenoic fatty acyl-CoA thioesters. When palmitoyl-CoA is employed as sole acyl group donor, the major lipid product is lysophosphatidic acid. 1-Acylglycerolphosphate acyltransferase of this yeast species has a rather strict specificity for monoenoic fatty acyl-CoA thioesters as acyl donor. These two acyltransferases are strongly inhibited in vitro by low concentrations of free fatty acids. 1-Acylglycerolphosphate acyltransferase is much more susceptible to fatty acid inhibition than glycerolphosphate acyltransferase. The inhibition is dependent not only on the concentration of fatty acid, but also on the length of exposure to fatty acid. Both saturated and unsaturated fatty acids inhibit the acyltransferase activities. The inhibitory effects of fatty acids cannot be ascribed to a nonspecific surfactant action of fatty acids. The present results support the view that free fatty acid serves as a regulator of glycerolipid synthesis.

Acyl Coenzyme A↗
PubMed1977

Simple, refined fluorometric method for measuring cystyl-amino peptidase activity.

Cystyl-amino peptidase (EC 3.4.11.3) activity in serum or plasma was measured fluorometrically using L-cystine-di-beta-naphthylamide in the absence and presence of thiol such as mercaptoethanol. In the presence of thiol, L-cystine-di-beta-naphthylamide is converted to L-cysteine-beta-naphthylamide, and the enzyme activity to hydrolyze L-cysteine-beta-naphthylamide can be measured, while in the absence of thiol, the enzyme activity to hydrolyze L-cystine-di-beta-naphthylamide is determined. Thiol added did not affect various aminopeptidase activities. The present method is able to measure the enzyme activity hydrolyzing L-cystine-di-beta-naphthylamide and L-cysteine-beta-naphthylamide simultaneously and separately using only L-cysteine-di-beta-naphthylamide. This method is simple, sensitive and useful in clinical routine work, assessing placental function for the evaluation of the pregnant status.

Amides↗
PubMed1976

Autoregulatory system of insulin degradation in liver. II. Relationship between blood insulin levels and GSH-dependent insulin degrading activity in liver and blood.

An autoregulatory system of insulin degradation in the liver in which the rate of insulin metabolism changes in response to fluctuation in its blood levels, was investigated. In the plasma of rats and man in the absence of reduced glutathione (GSH), insulin degradation was not observed, but when a sufficient amount of reduced glutathione was added, the plasma did degrade insulin. This GSH-dependent insulin degrading activity in plasma was quite similar to that in liver in its nature. In rats, this GSH-dependent insulin degrading activity in the liver and plasma was fluctuated in response to fluctuation in the blood insulin levels, and the GSH-dependent insulin degrading activity in plasma was well correlated with that in the liver. Similarly, in man the GSH-dependent insulin degrading activity in plasma was changed in response to fluctuation in the blood insulin levels. In plasma under the physiologic conditions, there is an insufficient amount of reduced glutathione to elicit the insulin degrading activity, but in the liver there is a sufficient amount of reduced glutathione to manifest this activity. This evidence further supports the concept that an autoregulatory system of insulin degradation in the liver exists in man.

Animals↗
PubMed1975

Simple, sensitive method for measuring plasmin and plasminogen activity in plasma.

We describe a sensitive, simple, and rapid method for measuring plasmin and plasminogen in plasma, with fibrinogen as substrate. The assay can be done within 1 h. Plasma is diluted 20-fold with buffer and 0.1 ml (5 mul of original plasma) is incubated for 5 min at 37 degrees C, with or without 400 units of streptokinase. Then 2.0 ml of fibrinogen solution is added, the mixture again incubated (37 degrees C, 5 min), and the reaction stopped. The amount of tyrosine liberated from the fibrinogen is measured and is related to activity. This method is suitable for routine clinical work if the same batch of fibrinogen is used.

Enzyme Activation↗