Guthmann M, Pastori R, Moreno S
Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Ciudad, Universitaria-Pebellón, Buenos Aires, Argentina.
Cell Signal. 1990;2(4):395-402. doi: 10.1016/0898-6568(90)90070-q.
Partial activation of Mucor rouxii cAMP-dependent protein kinase by cAMP was obtained when kemptide was used as substrate, but complete activation was attained with cAMP plus protamine or histone. Full activation could not be achieved by increasing kemptide or cAMP concentration. Complete activation by cAMP could be obtained by addition of 10 microM polylysine, 10 microM lysine-rich histone or 0.5 mM spermine plus spermidine. The degree of stimulation could be up to 5-fold, depending on the amount of enzyme in the assay. The same concentrations of polycations increased 1.5-2.3-fold the Vmax of kemptide phosphorylation by the free catalytic subunits of both Mucor and bovine heart protein kinases; 10 microM polyarginine inhibited completely the activity of both enzymes.
当使用肯普肽作为底物时，cAMP可使鲁氏毛霉cAMP依赖性蛋白激酶部分激活，但cAMP加鱼精蛋白或组蛋白可实现完全激活。增加肯普肽或cAMP浓度无法实现完全激活。添加10微摩尔聚赖氨酸、10微摩尔富含赖氨酸的组蛋白或0.5毫摩尔精胺加亚精胺可使cAMP实现完全激活。刺激程度可达5倍，具体取决于测定中酶的量。相同浓度的聚阳离子使毛霉和牛心蛋白激酶的游离催化亚基对肯普肽磷酸化的Vmax增加1.5至2.3倍；10微摩尔聚精氨酸完全抑制这两种酶的活性。
