van der Meer R A, Jongejan J A, Duine J A
Department of Microbiology and Enzymology, Delft University of Technology, The Netherlands.
FEBS Lett. 1988 Apr 25;231(2):303-7. doi: 10.1016/0014-5793(88)80838-x.
Treatment of homogeneous dopamine beta-hydroxylase (DBH) preparations from bovine adrenals with the inhibitor phenylhydrazine (PH) changed the structureless absorption spectrum of DBH into spectra with a maximum at 350 nm. A product with this absorption spectrum could be detached with pronase, enabling its isolation. It appeared to be the C(5) hydrazone of pyrroloquinoline quinone (PQQ) and PH, as judged from its properties and the fact that it could be transformed into PQQ itself. From the yield obtained a ratio of 0.85 PQQ per enzyme subunit was calculated. In contrast to copper-quinoprotein amine oxidases (EC 1.4.3.6), hydrazone formation in DBH did not require saturation of the mixture with O2. DBH is the first copper-quinoprotein hydroxylase found so far. The implications of this finding for the current views on mechanism of action and inhibition by hydrazines are discussed. The success of the recently developed 'hydrazine method' [(1987) FEBS Lett. 221, 299-304] for all different types of amine oxidoreductases, suggest that the method could also be applied to other enzymes for which hydrazines are inhibitors and where the identity of the cofactors has not been established or the presence of PQQ is suspected.
用抑制剂苯肼（PH）处理来自牛肾上腺的均一性多巴胺β-羟化酶（DBH）制剂，可使DBH无结构的吸收光谱转变为在350nm处有最大值的光谱。具有这种吸收光谱的产物可用链霉蛋白酶分离出来，从而实现其分离。从其性质以及它可转化为吡咯喹啉醌（PQQ）本身这一事实判断，它似乎是PQQ与PH的C(5)腙。根据获得的产量计算出每个酶亚基含0.85个PQQ的比例。与铜醌蛋白胺氧化酶（EC 1.4.3.6）不同，DBH中腙的形成不需要混合物用O2饱和。DBH是迄今为止发现的首个铜醌蛋白羟化酶。讨论了这一发现对当前关于肼的作用机制和抑制作用观点的影响。最近开发的“肼法”[（1987年）《欧洲生物化学学会联合会快报》221，299 - 304]对所有不同类型的胺氧化还原酶均成功，这表明该方法也可应用于其他以肼为抑制剂且辅因子身份尚未确定或怀疑存在PQQ的酶。
