非洲爪蟾卵母细胞和胚胎中的丙酮酸激酶同工酶

Pyruvate kinase isozymes in oocytes and embryos from the frog Xenopus laevis.

Dworkin M B, Segil N, Dworkin-Rastl E

Department of Biological Sciences, Sherman Fairchild Center, Columbia University, New York, NY 10027.

Comp Biochem Physiol B. 1987;88(3):743-9. doi: 10.1016/0305-0491(87)90238-0.

Abstract

The kinetic characteristics of pyruvate kinase isozymes from oocytes, embryos, liver and skeletal muscle from the clawed frog Xenopus laevis were measured in cell extracts. 2. The muscle and liver isozymes display Michaelis-Menten kinetics with Kms for phosphoenolpyruvate (PEP) of 0.02 and 0.05 mM, respectively. 3. Pyruvate kinase from oocytes and embryos displays cooperative kinetics for PEP with a Km of about 0.15 mM; the kinetics become hyperbolic and the Km for PEP is reduced to 0.05 mM in the presence of microM concentrations of fructose-1,6-bisphosphate. 4. These data serve to characterize pyruvate kinase activity in oocytes and embryos and the kinetics are compared to mammalian pyruvate kinase isozymes.

摘要

在非洲爪蟾卵母细胞、胚胎、肝脏和骨骼肌的细胞提取物中，对丙酮酸激酶同工酶的动力学特性进行了测定。2. 肌肉和肝脏同工酶呈现米氏动力学，对磷酸烯醇式丙酮酸（PEP）的Km值分别为0.02和0.05 mM。3. 卵母细胞和胚胎中的丙酮酸激酶对PEP呈现协同动力学，Km约为0.15 mM；在微摩尔浓度的果糖-1,6-二磷酸存在时，动力学变为双曲线型，PEP的Km值降至0.05 mM。4. 这些数据用于表征卵母细胞和胚胎中的丙酮酸激酶活性，并将该动力学与哺乳动物丙酮酸激酶同工酶进行比较。