2-Amino-3-ketobutyrate-CoA ligase from beef liver mitochondria: an NMR spectroscopic study of low-barrier hydrogen bonds of a pyridoxal 5'-phosphate-dependent enzyme.
2-Amino-3-ketobutyrate-CoA ligase from beef liver mitochondria: an NMR spectroscopic study of low-barrier hydrogen bonds of a pyridoxal 5'-phosphate-dependent enzyme.
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来自牛肝线粒体的 2-氨基-3-酮丁酸-CoA 连接酶：吡哆醛 5-磷酸依赖性酶的低势垒氢键的 NMR 光谱研究。
DOI：
10.1021/bi00010a027
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Davis,L
中科院分区：
文献类型：
--
作者：
Tong,H;Davis,L
1994年12月2日接收的修订版Mandarin pt ®摘要：2-氨基-3-酮丁酸-CoA连接酶（AKB-连接酶，EC 2.3）中与低势垒氢键相关的质子研究。1.29）的NMR。当在600 MHz下记录AKB连接酶的NMR谱时，在15-20 ppm范围内观察到三个共振。这些低势垒氢键分别与连接酶活性位点的侧链质子、PLP吡啶环氮质子和PLP Schiff碱质子相关联。吡啶质子的化学位移为19.10 ppm，席夫碱质子的化学位移为14.90 ppm。在16.20ppm处共振的第三低势垒氢键相关质子被分配给侧链基团的质子。当磷酸吡哆醛从连接酶中被移除时，所有三个共振都消失了。与NOE偶联一致，侧链基团质子应接近吡哆醛5 '-磷酸盐的席夫碱氮的质子。研究了温度、pH值、底物和NOE对三种共振态的影响，并对质子进行了归属。本报告中描述的三个低势垒氢键可用于锚2-氨基-3-酮丁酸-CoA连接酶的活性位点中的辅因子。2-氨基-3-酮丁酸-CoA连接酶（AKB-连接酶）1在与L-苏氨酸脱氢酶（TDH，EC 1.1. 1.103），在真核和原核细胞中催化L-苏氨酸和甘氨酸之间的相互转化（Mcgilvray和Morris，1969; Bell和Turner，1976 a，B; Dale，1978; Bird和纳恩，1979; Komatsubara等人，1978年; Bird等人，1984; Boylan & Dekker，1981）。研究表明，生物系统中的苏氨酸主要通过该代谢途径降解（Bird &纳恩，1983; Ravnikar &萨默维尔，1987; Aoyama & Motokawa，1981）。2-氨基-3-酮丁酸-CoA连接酶已从牛肝线粒体中纯化（Tong & Davis，1994）。吡哆醛5 '-磷酸（PLP）是一种必需的辅酶，
Revised Manuscript Received December 2, 1994® abstract: A study of protons associated with low-barrierhydrogen bonds in 2-amino-3-ketobutyrate—CoA ligase (AKB-ligase, EC 2.3. 1.29) by NMR is reported. Three resonances are observed in the range of Óh= 15-20 ppm when the NMR spectrum of AKB-ligase is recorded at 600 MHz. These lowbarrier hydrogen bonds are associated respectively with a side chain proton, the PLP pyridinium ring nitrogen proton, and the PLP Schiff base proton at the active site of the ligase. The pyridinium proton has been assigned a chemical shift of 19.10 ppm and the Schiff base proton 14.90 ppm. The third low-barrier hydrogen bond associated proton resonating at 16.20 ppm is assigned to a proton of a side chain group. All three resonances disappear when pyridoxal phosphate is removedfrom the ligase. Consistent with NOE coupling, the side chain group proton should be close to the proton of the Schiff base nitrogen of the pyridoxal 5'-phosphate. The effects of temperature, pH, substrate, and NOE on the three resonances are also studied, in order to assign the protons. The three low-barrier hydrogen bonds described in this report may serve to anchor the cofactorin the active site of 2-amino-3-ketobutyrate—CoA ligase.2-Amino-3-ketobutyrate—CoA ligase (AKB-ligase) 1 functions in a coupled system with L-threonine dehydrogenase (TDH, EC 1.1. 1.103), to catalyze interconversion between L-threonine and glycine in both eukaryotic and prokaryotic cells (Mcgilvray & Morris, 1969; Bell & Turner, 1976a, b; Dale, 1978; Bird & Nunn, 1979; Komatsubara et al., 1978; Bird et al., 1984; Boylan & Dekker, 1981). Studies showed that threonine in biological systems is degraded mainly through this metabolic pathway (Bird & Nunn, 1983; Ravnikar & Somerville, 1987; Aoyama & Motokawa, 1981). 2-Amino-3-ketobutyrate—CoA ligase has been purified from beef liver mitochondria (Tong & Davis, 1994). Pyri-doxal 5'-phosphate (PLP) is an essential coenzyme for the