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Properties of palmityl‐CoA: L‐α‐glycerolphosphate acyl transferase from bovine mammary microsomes
Author(s) -
Gross M. J.,
Kinsella J. E.
Publication year - 1974
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02532617
Subject(s) - microsome , chemistry , chromatography , bovine serum albumin , transferase , biochemistry , coenzyme a , phosphatidic acid , acylation , enzyme , phospholipid , reductase , membrane , catalysis
Palmityl‐coenzyme A: L‐α‐glycerolphosphate acyltransferase is the most active acyltransferase of bovine mammary microsomes, with a specific activity ranging from 8–20 nmoles min −1 mg −1 protein. Corresponding acylation rates of 2.2, 1.4, 2.1, and 0.6 nmoles min −1 mg −1 were obtained for myristyl‐, stearyl‐, oleyl‐ and linoleyl‐coenzyme A, respectively. Optimum pH of palmityltransferase was 7.7, and activity was not affected by buffer molarity in range 25–150 mM. Inhibitory effects of palmityl‐coenzyme A (10 μM/0.1 mg microsomal protein) was relieved by bovine serum albumin. Sonication magnesium and ethylenediaminetetraacetic acid enhanced activity. Delipidation of microsomes reduced activity by 84%; restoration of extracted lipids achieved 70% of original activity. Apparent Km and Vmax values of 4.1 and 260 μM and 9.5 and 8.2 nmole min −1 mg −1 were determined for palmityl‐coenzyme A and D,L‐α‐glycerolphosphate, respectively, using untreated microsomes. The enzyme was stable as lyophilized microsomes when stored at −30 C. Phosphatidic acid was the major product and marked quantities of diglycerides were formed, especially when microsomal protein was increased.