Ryzlak M T, Pietruszko R
Center of Alcohol Studies, Rutgers University, Piscataway, NJ 08855-0969.
Biochim Biophys Acta. 1988 Jun 13;954(3):309-24. doi: 10.1016/0167-4838(88)90086-6.
In an attempt to characterize enzymes from human brain capable of dehydrogenating short chain aliphatic aldehydes, four groups of enzymes which catalyze inorganic phosphate-dependent reversible dehydrogenation of glyceraldehyde 3-phosphate as well as short chain aldehydes have been purified and characterized. Three enzyme groups are visualized as multiple bands on isoelectric focusing: E6.6 (pI 6.65, 6.75, 6.85); E6.8 (pI 6.8, 6.9); E8.5 (pI 8.5, 8.6); one enzyme, E9.0, is seen as a single band pI 9.0. The subcellular localization of E6.8, E8.5 and E9.0 appears to be mitochondrial. The mitochondrial enzymes differ slightly in molecular weight: E6.8 is 142,000 with subunits of 36,000 and 38,000; E8.5 is 120,000 with a subunit weight of 29,500; E9.0 is 133,000 with a subunit of 33,000. The E8.5 and E9.0 enzymes also appear to contain Zr as part of their molecular structure. E6.6 (subcellular localization uncertain) is a dimer with a molecular weight of 98,000 and two subunits of 58,000 and 61,000. The specific activity with glyceraldehyde-3-phosphate is: E6.6, 8.6 IU/mg; E6.8, 13 IU/mg; E8.5, 158 IU/mg; E9.0, 620 IU/mg. With glyceraldehyde 3-phosphate and 1,3-diphosphoglyceric acid and Km values of all the enzymes are similar (10-40 microM), except for E6.8 whose Km for glyceraldehyde 3-phosphate is very sensitive to pH and is extremely low at pH 7.0 (2 microM), while being considerably higher than that for the other enzymes at pH 9.0 (170 microM). The molecular properties, Km values as well as high specific activity with glyceraldehyde 3-phosphate identify E6.8, E8.5 and E9.0 as glyceraldehyde-3-phosphate dehydrogenases (EC 1.2.1.12). The catalytic properties of E6.6 are similar to those of E6.8, E8.5 and E9.0, but its molecular properties are different, precluding definite identification.
为了鉴定人脑中能够使短链脂肪醛脱氢的酶，已对四组能催化3-磷酸甘油醛以及短链醛的无机磷酸依赖性可逆脱氢反应的酶进行了纯化和特性分析。在等电聚焦上，有三组酶表现为多条带：E6.6（等电点6.65、6.75、6.85）；E6.8（等电点6.8、6.9）；E8.5（等电点8.5、8.6）；一种酶E9.0表现为等电点9.0的单一条带。E6.8、E8.5和E9.0的亚细胞定位似乎在线粒体。线粒体酶的分子量略有不同：E6.8为142,000，亚基分子量为36,000和38,000；E8.5为120,000，亚基分子量为29,500；E9.0为133,000，亚基分子量为33,000。E8.5和E9.0酶似乎还含有锆作为其分子结构的一部分。E6.6（亚细胞定位不确定）是一种二聚体，分子量为98,000，两个亚基分子量分别为58,000和61,000。对3-磷酸甘油醛的比活性为：E6.6，8.6 IU/mg；E6.8，13 IU/mg；E8.5，158 IU/mg；E9.0，620 IU/mg。对于3-磷酸甘油醛和1,3-二磷酸甘油酸，所有酶的Km值相似（10 - 40 microM），但E6.8除外，其对3-磷酸甘油醛的Km值对pH非常敏感，在pH 7.0时极低（2 microM），而在pH 9.0时远高于其他酶（170 microM）。E6.8、E8.5和E9.0的分子特性、Km值以及对3-磷酸甘油醛的高比活性表明它们是3-磷酸甘油醛脱氢酶（EC 1.2.1.12）。E6.6的催化特性与E6.8、E8.5和E9.0相似，但其分子特性不同，因此无法明确鉴定。
