コイ,ウナギおよびニジマス肝臓のホスホフルクトキナ-ゼの特性〔英文〕

概要

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Phosphofructokinase (EC 2.7.1.11) from rainbow trout liver, eelliver, and carp hepatopancreas was purified by ammonium sulfate fractionation, followed by ethanol fractionation, DEAF-cel-lulose chromatography, and Sephadex G-200 gel filtration. The rainbow trout and eel enzymes were obtained as a homogeneous peak by gel filtration. In the carp liver, there was a considerable loss of enzyme activity during dialysis. The molecular weight of the enzyme was estimated to be about 340, 000 by gel filtration, and the pH optimum of the activity was found to be around 8. The Km values for F6P of the rainbow trout, eel and carp enzymes were 19, 24, and 71μM, respectively, and that for ATP were 15, 19, and 22μM, respectively. The reaction mechanism by which the carp enzyme differed from that of the other two fish enzymes. Fish phosphofructokinase required Mg2+ for activation. The Km values for Mg2+ of the three fish enzymes ranged from O.83 to 1.1mM. The enzyme showed maximum activity around i mM ATP in the presence of 2mM F6P beyond which the activity decreased with increasing ATP concentration. ADP inhibited the enzyme activity, depending of F6P and ATP concentrations. AMP was found to activate the enzyme in the presence of ATP at inhibitory concentrations. The enzyme also utilized ITP, UTP, and CTP as a phosphoryl donor.
日本水産學會の論文