アフリカツメガエルXenopus laevis分岐鎖a-ケト酸脱水素酵素複合体のデカルボキシラーゼ成分の性質

概要

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Branched-chain a-keto acid dehydrogenase complex(BCKADC)contains decarboxylase(EL), dihydrolipoyl transacylase, and dihydrolipoyl dehydrogenase as catalytic components. To characterize BCKADC of amphibian, mitochondrial extract of Xenopus laevis liver was subjected to immunoblotting analysis using rat anti EL antibodies. As a result, three immunoreactive proteins were detected; the molecular mass of proteins was estimated to be 36,37 and 46 kDa. Incubation of liver mitochondria from Xenopus laevis prior to solubilization of EL resulted in no significant change in their appearance and amount. These proteins were also detected in heart of Xenopus laevis as well as liver of the amphibian. Sucrose density gradient centrifugation under the condition, which brings dissociation of BCKADC to each component enzyme, revealed that the three proteins of Xenopus laevis moved together through the gradient. The density that three proteins settled corresponded well with that of rat EL did. Present results obtained here showed that EL of Xenopus laevis contains three proteins at least, and the 47 kDa protein corresponds to EL a subunit in comparison with molecular mass of EL a of other species.