earticle

영어

NAD+ analogs, 8-( 6-aminohexyl) aminonicotinamide adenine dinucleotide and N6-[(6- aminohewl)-carbamoylmethyl]- NAD+, were imobilized on bovine caseins by the action of hansglutaminase. It appears that NAD+ analogs bind with aS1-and B-caseins through formation of the r-glutamylamine bond between the amino groups attached to the hexyl chains in NAD+ analogs and the glutaminyl residues in caseins. The NAD+ analogs immobilized on the caseins were enzymatically reducible by alcohol dehydrogenase. B-Casein was more useful carrier than the S1-casein and 8-substituted NAD+ analog was more effective than N6-substituted one in immobilization. Michaelis constant of 8-substituted NAD+ analog immobilized on B-casein in alcohol dehydrogenase reaction was similar to that of free from of NAD+ and that of NAD+ analog. Immobilized NAD+ was much more stable at alkaline pH than free NAD+ and its analog while maximum velocity was reduced to 31% of the free NAD+ analog. The coenzyme casein conjugated was recovered almost completely in casein precipitated by calcium.

한국어

보효소고분자화를 위한 담체로서 B- casein에 NAD/+ 를 효소법으로 고정화하였다. 21개의 glutamine 잔기를 함유하는 수용성고분자물질로서 transglutaminase 촉매작용에 의해 NAD/+analog의 amino기와 r-glutamylamine bond를 형성하여 결합하였다. B-Casein은 /ar1+(1분자내에 15개의 glutamine잔기를 함유)에 비하여 효과적인 고정화담체이었으며 8-(6-amino hexyl) aminonicotinamide ade-nine dinucleotide는 N6-[(6-aminohexyl)-carba-moylmethy]-NAD에 비하여 고정화수율이 높았다. 고정화에 있어 NAN의 첨가는 필수적이었다. 고정화 NAD Km치는 NAD또는 NADanalog와 비슷하였으나 max.rate는 고정화하므로써 31% 감소되었다. 그러나 고정화하므로써 NAD의 alkaline pH에서의 안정성은 증대되었으며, 고정화 보효소를 칼슘침전하여 분리회수하였을 경우에도 보효소 활성을 유지, NAD형 (산화형)과 NADH형(환원형)으로 상호전환되므로써 재생되었다.