Langston-Unkefer P J, Lee T C
Department of Agronomy, University of Wisconsin, Madison Wisconsin 53706.
Plant Physiol. 1985 Oct;79(2):436-40. doi: 10.1104/pp.79.2.436.
A significant lag phase was observed in the accumulation of product for the reaction catalyzed by pyruvate decarboxylase (PDC) purified from mature maize kernels. The effects of pH, pyruvate, potassium chloride, PDC concentration, and Mg(2+)-thiamine pyrophosphate upon this lag and upon the observed cooperativity were investigated. PDC preincubated with Mg(2+)-thiamine pyrophosphate for six days had Michaelis-Menten kinetics, a Hill number of 1, and no apparent lag phase. The degree of saturation of PDC with Mg(2+)-thiamine pyrophosphate appears to have a central role in controlling the lag phase and the degree of cooperativity.
从成熟玉米籽粒中纯化得到的丙酮酸脱羧酶（PDC）所催化的反应，在产物积累过程中观察到明显的延迟期。研究了pH、丙酮酸、氯化钾、PDC浓度以及Mg(2+)-硫胺素焦磷酸对该延迟期和所观察到的协同性的影响。用Mg(2+)-硫胺素焦磷酸预孵育6天的PDC具有米氏动力学、希尔系数为1且无明显延迟期。PDC与Mg(2+)-硫胺素焦磷酸的饱和程度似乎在控制延迟期和协同程度方面起着核心作用。
