title: [Separation of fractions of phosphoprotein phosphatase and its protein inhibitors by isoelectrofocusing].
abstract: Individual molecular forms of phosphoprotein phosphatase from albino rat cardiac muscle were separated by isoelectrofocusing, resulting in a few fractions differing in pI (5.1, 5.4, 5.9-6.1 (double peak) and 7.1, respectively). Isoelectrofocusing of a purified enzyme preparation also allowed to isolate and characterize two protein inhibitors of the enzyme. The first one with pH 6.5-6.7 is similar to the thermostable phosphoprotein phosphatase inhibitor known from literature. This protein inhibits the enzyme activity by 90%; its effect is not decreased after 5-min heating at 95 degrees. The other inhibitor protein with pH 5.6-5.8 is thermolabile. When the enzyme activity was decreased 2.5-fold prior to thermal treatment, the latter protein lost this ability after heating at 95 degrees and inhibited the enzyme only by 9%. It is assumed that inhibitory proteins beside low molecular weight effectors can be involved in the mechanisms of the post-synthetical operative modification of phosphoprotein phosphatase function.
mesh_terms: D000818:Animals; D007525:Isoelectric Focusing; D009206:Myocardium / Q000201:enzymology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D011506:Proteins / Q000302:isolation & purification* / Q000502:physiology; D051381:Rats
chemical_list: D011506:Proteins; D010749:Phosphoprotein Phosphatases
vernacular_title: Razdelenie fraktsiĭ fosfoproteinfosfatazy i eë belkovykh ingibitorov metodom izoelektrofokusirovaniia.