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Biomedical subjects

S Numa

Publications and source records attributed to S Numa.

At least 163 records · Page 9Linked to original sources
PubMed1972

Resolution and reconstitution of the phosphatidate-synthesizing system of rat-liver microsomes.

The phosphatidate-synthesizing system of rat-liver microsomes was resolved into two component enzymes, glycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase. The resolution is effected by sucrose density gradient centrifugation in the presence of a nonionic detergent, Triton X-100. Combination of both enzymes results in reconstitution of the phosphatidate-synthesizing system. These results establish that two distinct enzymes, glycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase, are required for synthesis of phosphatidic acid from sn-glycerol 3-phosphate.Furthermore, the 1-acylglycerolphosphate acyltransferase preparation efficiently uses unsaturated (or saturated) fatty acyl-CoA as acyl donor. Our previous studies showed that the glycerolphosphate acyltransferase preparation catalyzes formation of 1-acylglycerol 3-phosphate, using preferentially saturated fatty acyl-CoA as acyl donor. These findings indicate that the reconstituted system is capable of yielding phosphatidic acid with an asymmetric fatty acid distribution.

Acetyltransferases↗
PubMed1971

Synthesis and degradation of liver acetyl coenzyme A carboxylase in genetically obese mice.

The total cytosol activity of acetyl-CoA carboxylase (acetyl-CoA:CO(2) ligase (ADP), EC 6.4.1.2) in the liver is known to be 6- to 10-fold higher in genetically obese hyperglycemic mice (C57BL/6J-ob) than in nonobese mice. The results of immunochemical titrations, Ouchterlony double-diffusion analysis, and kinetic and heat inactivation studies indicated that this rise in the level of carboxylase activity in liver extracts from obese mice was ascribed to an increase in the quantity of the enzyme protein, which was indistinguishable from that derived from nonobese mice. Combined immunochemical and isotopic techniques showed that the rate of synthesis of the carboxylase per liver was 7.7-fold higher in obese than in nonobese mice. The rate of degradation of the carboxylase was found to be 1.7-fold lower in obese than in nonobese mice, the half-life being 115 and 67 hr, respectively. These results indicate that the increase in the acetyl-CoA carboxylase content of the liver in obese mice is due mainly to a rise in the rate of enzyme synthesis, and in a minor degree, to a decrease in the rate of enzyme degradation.

Animals↗