| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Lipoyl-AMP : N^<epsilon>-lysine lipoyltransferase (lipoyltransferase) catalyzes the transfer of the lipoyl group from lipoyl-AMP to a lysine residue of the specific enzyme proteins. We have shown previously that the lipoyltransferase activities locate in mitochondria using apoH-protein of the glycine cleavage system as an accepter of the lipoyl group. In this study, we obtained the following results.
1.Purification and characterization of lipoyltransferases from bovine liver mitochondria-Lipoyltransferase II was purified to apparent homogeneity, whereas the final product of lipoyltransferase I still contained a minor contaminant. Although the two forms could be resolved on a hydroxylapatite column chromatography, they were indistinguishable, as judged by : (a) behavior during purification on ion exchange, hydrophobic, or affinity column ; (b) molecular mass determined by SDS-PAGE and gel exclusion chromatography (40 kDa) ; and (c) catalytic properties (substrate specificity, kinetic constants, and optimal pH). Both lipoyltransferase I and II could not use lipoic acid plus MgATP as a substrate in place of lipoyl-AMP.The lipoyltransferases transferred not only lipoyl group but also the acyl groups from hexanoyl-, octanoyl-and decanoyl-AMP to apoH-protein to a similar extent.
2.Both lilpoyltransferase I and II were able to transfere lipoyl group from lipoyl-AMP to lipoyl domains of acyltransferase comtonents, the other proteins having lipoyl group (s), of pyruvate, a-ketoglutarate, and branched chain a-keto acid dehydrogenase comprex.
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