Hunger-Glaser I, Linder M, Seebeck T
Institut fuer Allgemeine Mikrobiologie, University of Bern, Switzerland.
Mol Biochem Parasitol. 1999 May 15;100(1):43-52. doi: 10.1016/s0166-6851(99)00025-0.
The insect form of Trypanosoma brucei depends on respiration for its energy requirements. It contains a fully functional mitochondrion with a complete citric acid cycle. Most of its enyzmes have been characterized to date. The current study presents the characterization of the histidine phosphorylation activity of one of the few remaining enzymes, succinyl CoA synthetase. The trypanosomal enyzme was identified by partial purification, followed by direct protein sequencing. It is rapidly phosphorylated, presumably through auto-phosphorylation, using either ATP or GTP as phosphate donors. The phosphorylation occurs exclusively on histidine residues. The histidine-bound phosphate can be donated to suitable phosphate acceptors in a rapid reaction. This phosphotransfer reaction is highly nucleotide selective, as only ADP, but none of the other nucleoside-diphosphates tested, can be used as a phosphate acceptor.
布氏锥虫的昆虫形态依靠呼吸作用来满足其能量需求。它含有一个功能完备的线粒体以及完整的柠檬酸循环。到目前为止，其大部分酶已得到表征。当前的研究展示了对剩余少数几种酶之一——琥珀酰辅酶A合成酶的组氨酸磷酸化活性的表征。通过部分纯化，随后进行直接蛋白质测序，鉴定出了锥虫的这种酶。它能快速磷酸化，推测是通过自身磷酸化，使用ATP或GTP作为磷酸供体。磷酸化仅发生在组氨酸残基上。与组氨酸结合的磷酸可以在一个快速反应中转移给合适的磷酸受体。这种磷酸转移反应具有高度的核苷酸选择性，因为只有ADP，而不是所测试的其他任何二磷酸核苷，能用作磷酸受体。
