Effect of bovine serum albumin on monoacyl- and diacylglycerol 3-phosphate formation in mitochondrial and microsomal fractions of rabbit hearts.
The formation of monoacyl- and diacylglycerol 3-phosphate (P) by rabbit heart mitochondrial and microsomal fractions was studied by varying the concentration of acyl-CoA and that of bovine serum albumin in the assay system. The two subcellular fractions were prepared by the conventional differential centrifugation technique. The optimal concentration of acyl-CoA for both mitochondrial and microsomal acylation of glycerol 3-P was shifted to a higher range of acyl-CoA concentrations by greater amounts of albumin. A similar shift in the acyl-CoA concentration-enzyme activity relationship was observed in the acylation reaction of 1-palmitoylglycerol 3-P by the heart microsomes. The addition of albumin increased slightly the rate of diacylglycerol 3-P accumulation but increased greatly the rate of monoacylglycerol 3-P accumulation at any concentration of acyl-CoA; the effect was observed with mitochondrial or microsomal fraction as the crude enzyme source. Moreover, palmitoyl-CoA and linoleoyl-CoA served equally well as the acyl donor for the acylation reaction. However, relatively more monoacyl- than diacylglycerol 3-P was accumulated in the assays with rabbit heart mitochondrial fraction in the presence of albumin, whereas more diacyl- than monoacylglycerol 3-P was formed by the microsomal fraction. As a result, the microsomal diacyl:monoacyl-glycerol 3-P ratio was invariably greater than the mitochondrial ratio at a given concentration of acyl-CoA and albumin.
D000818:Animals; D003065:Coenzyme A / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D007700:Kinetics; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000096:biosynthesis; D010743:Phospholipids / Q000096:biosynthesis*; D011817:Rabbits; D012710:Serum Albumin, Bovine / Q000494:pharmacology*
D005227:Fatty Acids; D010712:Phosphatidic Acids; D010743:Phospholipids; D012710:Serum Albumin, Bovine; D003065:Coenzyme A