Dell K R, Severson D L
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Calgary, Alberta, Canada.
Biochem J. 1989 Feb 15;258(1):171-5. doi: 10.1042/bj2580171.
Long-chain cis-unsaturated fatty acids could substitute for phosphatidylserine and activate bovine aortic protein kinase C in assays with histone as substrate. The optimal concentration was 24-40 microM for oleic, linoleic and arachidonic acids. With arachidonic acid, the Ka for Ca2+ was 130 microM and kinase activity was maximal at 0.5 mM-Ca2+. Diolein only slightly activated the oleic acid-stimulated enzyme at low physiological Ca2+ concentrations (0.1 and 10 microM). Oleic acid also stimulated kinase C activity, determined with a Triton X-100 mixed-micellar assay. Under these conditions, the fatty acid activation was absolutely dependent on the presence of diolein, but a Ca2+ concentration of 0.5 mM was still required for maximum kinase C activity. The effect of fatty acids on protein kinase C activity was also investigated with the platelet protein P47 as a substrate, since the properties of kinase C can be influenced by the choice of substrate. In contrast with the results with histone, fatty acids did not stimulate the phosphorylation of P47 by the aortic protein kinase C. Activation of protein kinase C by fatty acids may allow the selective phosphorylation of substrates, but the physiological significance of fatty acid activation is questionable because of the requirement for high concentrations of Ca2+.
在以组蛋白为底物的实验中，长链顺式不饱和脂肪酸可替代磷脂酰丝氨酸并激活牛主动脉蛋白激酶C。油酸、亚油酸和花生四烯酸的最佳浓度为24 - 40微摩尔。对于花生四烯酸，Ca2+的Ka为130微摩尔，激酶活性在0.5毫摩尔 - Ca2+时最大。在低生理Ca2+浓度（0.1和10微摩尔）下，二油精仅轻微激活油酸刺激的酶。油酸也刺激用Triton X - 100混合胶束测定法测定的激酶C活性。在这些条件下，脂肪酸激活绝对依赖于二油精的存在，但最大激酶C活性仍需要0.5毫摩尔的Ca2+浓度。还以血小板蛋白P47为底物研究了脂肪酸对蛋白激酶C活性的影响，因为激酶C的性质可能受底物选择的影响。与组蛋白的结果相反，脂肪酸不刺激主动脉蛋白激酶C对P47的磷酸化。脂肪酸对蛋白激酶C的激活可能允许底物的选择性磷酸化，但由于需要高浓度的Ca2+，脂肪酸激活的生理意义值得怀疑。
