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[摘要]：Curcumin modulates the activity of protein kinase C alpha (PKC alpha) when assayed in the presence of vesicles including phosphatidylcholine, phosphatidylserine and diacylglycerol. Increasing concentrations of curcumin progressively increased PKC alpha activity at concentrations lower than 20 mu M, but at higher concentrations of curcumin the activity decreased although, at concentrations of curcumin of up to 100 mu M the activity was always higher than the basal one (in the absence of curcumin). The maximum activity was reached at 3 mu M curcumin, at 20 and 30 mol% of phosphatidylserine, 10 mu M Ca2+ and 2 mol% diacylglycerol. The same type of modulation was observed when changing the concentration of phosphatidylserine, diacylglycerol and Ca2+. No effect of curcumin was found when the activity was assayed in the presence of Triton X-100 mixed micelles which included phosphatidylserine and diacylglycerol, indicating that the effect of curcumin was membrane-dependent. The pattern of binding of PKC alpha to membrane vesicles as a function of curcumin concentration closely correlated with the pattern of activating effect. It was concluded that the effect of curcumin on PKC alpha activity was related to its effect on the membrane, which may modulate the binding of the enzyme to the membrane. (C) 2011 Elsevier Inc. All rights reserved. |
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