Lespinat P A, Berlier Y, Fauque G, Czechowski M, Dimon B, Le Gall J
Biochimie. 1986 Jan;68(1):55-61. doi: 10.1016/s0300-9084(86)81068-9.
Different patterns have been found in the pH dependence of hydrogenase activity with enzymes purified from different species of Desulfovibrio. With the cytoplasmic hydrogenase from Desulfovibrio baculatus strain 9974, the pH optima in H2 production and uptake were respectively 4.0 and 7.5 with a higher activity in production than in uptake. The highest D2-H+ exchange activity was found also at pH 4.0 but the optima differed for the HD and the H2 components. Both similarly rose when the pH decreased from 9.0 to 4.5, but the rate of H2 evolution slowed whereas the HD evolution continued rising till pH values around 3.0 were reached. The H2 to HD ratio at pH above 4.5 was higher than one. With the periplasmic hydrogenase from Desulfovibrio vulgaris Hildenborough, the highest exchange activity was near pH 5.5, the same value as in hydrogen production. The periplasmic hydrogenase from Desulfovibrio gigas had in contrast the same pH optimum in the exchange (7.5-8.0) as in the H2 uptake. The ratio of H2 to HD was below one for both enzymes. These different patterns may be related to functional and structural differences in the three hydrogenases so far studied, particularly in the composition of their catalytic centers.
从不同种脱硫弧菌中纯化得到的氢化酶，其活性的pH依赖性呈现出不同模式。对于来自杆状脱硫弧菌菌株9974的细胞质氢化酶，产氢和吸氢的最适pH分别为4.0和7.5，产氢活性高于吸氢活性。最高的D2-H+交换活性也出现在pH 4.0时，但HD和H2组分的最适值不同。当pH从9.0降至4.5时，两者均类似地升高，但H2释放速率减慢，而HD释放持续升高，直至达到约3.0的pH值。pH高于4.5时，H2与HD的比率高于1。对于来自希氏脱硫弧菌的周质氢化酶，最高交换活性接近pH 5.5，与产氢时的值相同。相比之下，来自巨大脱硫弧菌的周质氢化酶在交换（7.5-8.0）和吸氢方面具有相同的最适pH。两种酶的H2与HD比率均低于1。这些不同模式可能与目前研究的三种氢化酶的功能和结构差异有关，特别是它们催化中心的组成。
