Pirozhkov S V, Panchenko L F
Biokhimiia. 1988 Sep;53(9):1443-8.
The enzymes catalyzing the NAD-dependent oxidation of malonic dialdehyde (MDA) were isolated from rat liver extracts. Upon 5'-AMP-Sepharose chromatography MDA dehydrogenase was separated into two isoforms, I and II. Isoform I was eluted from the affinity carrier with a 0.1 M phosphate buffer pH 8.0. This isoform had a broad substrate specificity towards aliphatic and aromatic aldehydes. Kinetic studies showed that short- and medium-chain aliphatic aldehydes (C2-C6) were characterized by the lowest Km values and the highest Vmax values. The Km' values for MDA and acetaldehyde were 2.8 microM and 0.69 microM, respectively. Isoform II was eluted with a 0.1 M phosphate buffer pH 8.0 containing 0.5 mM NAD, was the most active with medium- and long-chain aliphatic aldehydes (C6-C11) and had Km values for MDA and acetaldehyde equal to 37 microM and 52 microM, respectively. Isoform I was much more sensitive towards disulfiram inhibition than isoform II. Both isoforms had an identical molecular mass (93 kD) upon gel filtration. It is concluded that MDA dehydrogenase isoform I is identical to mitochondrial aldehyde dehydrogenase having a low Km for acetaldehyde, whereas isoform II may be localized in liver cytosol. The role of aldehyde dehydrogenases in the metabolism of aldehydes derived from lipid peroxidation is discussed.
从大鼠肝脏提取物中分离出催化丙二醛（MDA）依赖NAD氧化的酶。经5'-AMP-琼脂糖层析，MDA脱氢酶被分离为两种同工型，I和II。同工型I用0.1M pH 8.0的磷酸盐缓冲液从亲和载体上洗脱下来。该同工型对脂肪族和芳香族醛具有广泛的底物特异性。动力学研究表明，短链和中链脂肪族醛（C2 - C6）的特征是Km值最低，Vmax值最高。MDA和乙醛的Km'值分别为2.8μM和0.69μM。同工型II用含0.5mM NAD的0.1M pH 8.0的磷酸盐缓冲液洗脱，对中链和长链脂肪族醛（C6 - C11）活性最高，MDA和乙醛的Km值分别为37μM和52μM。同工型I比同工型II对双硫仑抑制更敏感。凝胶过滤时两种同工型的分子量相同（93kD）。得出的结论是，MDA脱氢酶同工型I与对乙醛具有低Km的线粒体醛脱氢酶相同，而同工型II可能定位于肝细胞溶质中。讨论了醛脱氢酶在脂质过氧化衍生醛代谢中的作用。
