Packman L C, Stanley C J, Perham R N
Biochem J. 1983 Aug 1;213(2):331-8. doi: 10.1042/bj2130331.
Intramolecular coupling of active sites in the pyruvate dehydrogenase multienzyme complexes of Escherichia coli, ox heart and Bacillus stearothermophilus was measured at various temperatures. As the temperature was raised, the extent of active-site coupling was found to increase, approaching a maximum near the physiological growth temperature of the organism. Under these conditions, a single pyruvate dehydrogenase (lipoamide) dimer appeared able to cause a rapid (20s) reductive acetylation of probably all 24 polypeptide chains in the dihydrolipoamide acetyltransferase core of the enzyme complex from E. coli at 37 degrees C, and of most if not all of the 60 polypeptide chains in the dihydrolipoamide acetyltransferase cores of the enzymes from ox heart and B. stearothermophilus at 37 degrees C and 60 degrees C respectively. Experiments designed to measure the inter-core and intra-core migration of enzyme subunits suggested that, in the bacterial enzymes at least, this was not a major contributor to active-site coupling.
在不同温度下测定了大肠杆菌、牛心和嗜热脂肪芽孢杆菌丙酮酸脱氢酶多酶复合物中活性位点的分子内偶联情况。随着温度升高，发现活性位点偶联程度增加，在生物体的生理生长温度附近接近最大值。在这些条件下，单个丙酮酸脱氢酶（硫辛酰胺）二聚体似乎能够在37℃时使大肠杆菌酶复合物中二氢硫辛酰胺乙酰转移酶核心中可能所有24条多肽链快速（20秒）进行还原乙酰化，在37℃和60℃时分别使牛心和嗜热脂肪芽孢杆菌酶的二氢硫辛酰胺乙酰转移酶核心中大部分（如果不是全部）60条多肽链快速进行还原乙酰化。旨在测量酶亚基在核心间和核心内迁移的实验表明，至少在细菌酶中，这不是活性位点偶联的主要因素。
