Graczer Eva, Bacso Andras, Konya Denes, Kazi Adrian, Soos Tibor, Molnar Laura, Szimler Tamas, Beinrohr Laszlo, Szilagyi Andras, Zavodszky Peter, Vas Maria
Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H- 1117 Budapest, Magyar tudósok korutja 2., Hungary; H-1519 Budapest, P. O. Box 286., Hungary.
Protein Pept Lett. 2014;21(12):1295-307.
3-Isopropylmalate dehydrogenase (IPMDH) from Mycobacterium tuberculosis (Mtb) may be a target for specific drugs against this pathogenic bacterium. We have expressed and purified Mtb IPMDH and determined its physicalchemical and enzymological properties. Size-exclusion chromatography and dynamic light scattering measurements (DLS) suggest a tetrameric structure for Mtb IPMDH, in contrast to the dimeric structure of most IPMDHs. The kinetic properties (kcat and Km values) of Mtb IPMDH and the pH-dependence of kcat are very similar to both Escherichia coli (Ec) and Thermus thermophilus (Tt) IPMDHs. The stability of Mtb IPMDH in 8 M urea is close to that of the mesophilic counterpart, Ec IPMDH, both of them being much less stable than the thermophilic (Tt) enzyme. Two known IPMDH inhibitors, O-methyl oxalohydroxamate and 3-methylmercaptomalate, have been synthesised. Their inhibitory effects were found to be independent of the origin of IPMDHs. Thus, experiments with either Ec or Tt IPMDH would be equally relevant for designing specific inhibitory drugs against Mtb IPMDH.
结核分枝杆菌（Mtb）的3-异丙基苹果酸脱氢酶（IPMDH）可能是针对这种病原菌的特异性药物的靶点。我们已经表达并纯化了Mtb IPMDH，并测定了其物理化学和酶学性质。尺寸排阻色谱和动态光散射测量（DLS）表明Mtb IPMDH具有四聚体结构，这与大多数IPMDH的二聚体结构不同。Mtb IPMDH的动力学性质（kcat和Km值）以及kcat对pH的依赖性与大肠杆菌（Ec）和嗜热栖热菌（Tt）的IPMDH非常相似。Mtb IPMDH在8 M尿素中的稳定性与嗜温的对应物Ec IPMDH相近，两者都比嗜热（Tt）酶的稳定性低得多。已经合成了两种已知的IPMDH抑制剂，O-甲基草酰羟肟酸和3-甲基巯基苹果酸。发现它们的抑制作用与IPMDH的来源无关。因此，用Ec或Tt IPMDH进行的实验对于设计针对Mtb IPMDH的特异性抑制药物同样具有参考价值。
