Liguori M, Tessarolo D, Abbruzzese C, Giacanelli M
Research Laboratory of Service of Neuromuscular Diseases, San Camillo Hospital, Rome, Italy.
Biochem Mol Med. 1995 Oct;56(1):14-8. doi: 10.1006/bmme.1995.1050.
The L-malate NAD(P)+ oxidoreductase (decarboxylating) E.C.1.1.1.39 was purified from human skeletal muscle; the specific activity estimated in the presence of NAPD+ as coenzyme was approximately 15 mumol/min/mg. The apparent Vmax values for NAD+ (approximately 8 mumol/min/mg) and NADP+ (approximately 16 mumol/min/mg) show that the enzyme (in this tissue) is more active in the presence of NAPD+. This observation was confirmed by the estimation of enzymatic activity in competition experiments where both NAD+ and NADP+ were used together as coenzymes. The absence of pyruvate carboxylation and of oxalacetate decarboxylation activities demonstrates that the enzyme studied is E.C.1.1.1.39. In addition, the apparent Km values for NAD+ and NADP+ were calculated (15 and 0.05 mM, respectively). This paper provides the first demonstration of a NADP+ preferring activity of the enzyme in human skeletal muscle.
L-苹果酸NAD(P)+氧化还原酶（脱羧）E.C.1.1.1.39是从人体骨骼肌中纯化得到的；以NAPD+作为辅酶时所估计的比活性约为15微摩尔/分钟/毫克。NAD+（约8微摩尔/分钟/毫克）和NADP+（约16微摩尔/分钟/毫克）的表观Vmax值表明，该酶（在这种组织中）在NAPD+存在时活性更高。在将NAD+和NADP+一起用作辅酶的竞争实验中对酶活性的估计证实了这一观察结果。丙酮酸羧化活性和草酰乙酸脱羧活性的缺失表明所研究的酶是E.C.1.1.1.39。此外，还计算了NAD+和NADP+的表观Km值（分别为15和0.05毫摩尔）。本文首次证明了该酶在人体骨骼肌中具有对NADP+的偏好活性。
