Lester D S, Brumfeld V
Department of Membrane Research, Weizmann Institute of Science, Rehovot, Israel.
Int J Biol Macromol. 1990 Aug;12(4):251-6. doi: 10.1016/0141-8130(90)90005-u.
The changes in intrinsic spectral properties of protein kinase C were monitored upon association with its divalent cation and lipid activators in a model membrane system. The enzyme demonstrated changes in both its intrinsic fluorescence and far ultraviolet circular dichroism spectra upon association with lipid vesicles in the absence of calcium. The acidic phospholipid, phosphatidylserine, significantly quenched the intrinsic tryptophan fluorescence and was also the most potent lipid support for the phosphorylating activity of the enzyme. The enzyme was fully activated by a number of Ca2(+)-lipid combinations which correlated with maximal fluorescence quenching (40-50%) of available tryptophan residues in hydrophobic domains. The circular dichroism structure of the associated active-protein Ca2(+)-lipid complexes suggested different active enzyme secondary structures. However, the Ca2(+)-dependent changes in fluorescence and circular dichroism spectra were observed only after the enzyme associated with the lipid vesicles. These data suggest that protein kinase C has the properties of a complex multidomain protein and provides an additional perspective into the mechanism of protein kinase C activation.
在模型膜系统中，监测蛋白激酶C与其二价阳离子和脂质激活剂结合时其内在光谱特性的变化。在没有钙的情况下，该酶与脂质囊泡结合时，其内在荧光和远紫外圆二色光谱均发生了变化。酸性磷脂磷脂酰丝氨酸显著淬灭了内在色氨酸荧光，并且也是该酶磷酸化活性最有效的脂质支持物。该酶被多种Ca2(+)-脂质组合完全激活，这与疏水结构域中可用色氨酸残基的最大荧光淬灭（40-50%）相关。相关活性蛋白Ca2(+)-脂质复合物的圆二色结构表明存在不同的活性酶二级结构。然而，只有在酶与脂质囊泡结合后，才观察到荧光和圆二色光谱中依赖于Ca2(+)的变化。这些数据表明蛋白激酶C具有复杂多结构域蛋白的特性，并为蛋白激酶C激活机制提供了新的视角。
