Diglyceride kinase in human platelets.
Human platelets contain diglyceride kinase, an enzyme that catalyzes the phosphorylation of diacylglycerol by adenosine 5'-triphosphate to yield phosphatidic acid. The majority of the platelet enzyme is particulate-bound, and membrane fractions of platelet homogenates have a higher specific activity than granule fractions. Both deoxycholate and magnesium are necessary for optimal enzyme activity. The K(m) of the enzyme for adenosine 5'-triphosphate is 1.3 mm, and the apparent K(m) for diacylglycerol is 0.4 mm. The pH optimum is 6.6-6.8 in imidazole-HCl or maleate-NaOH buffer. The enzyme activity of platelets from normal subjects was similar to the activity from patients with renal and hepatic failure.
D000255:Adenosine Triphosphate; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D002021:Buffers; D002852:Chromatography, Ion Exchange; D002854:Chromatography, Paper; D002855:Chromatography, Thin Layer; D003840:Deoxycholic Acid / Q000494:pharmacology; D004912:Erythrocytes / Q000201:enzymology; D005989:Glycerides; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008214:Lymphocytes / Q000201:enzymology; D008274:Magnesium; D009994:Osmolar Concentration; D010743:Phospholipids / Q000096:biosynthesis; D010759:Phosphorus Isotopes; D010770:Phosphotransferases / Q000097:blood*; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013501:Surface-Active Agents / Q000494:pharmacology; D013997:Time Factors
D002021:Buffers; D005989:Glycerides; D010743:Phospholipids; D010759:Phosphorus Isotopes; D013439:Sulfhydryl Reagents; D013501:Surface-Active Agents; D003840:Deoxycholic Acid; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D008274:Magnesium