Fujiwara K, Okamura-Ikeda K, Motokawa Y
Institute for Enzyme Research, University of Tokushima, Japan.
FEBS Lett. 1991 Nov 18;293(1-2):115-8. doi: 10.1016/0014-5793(91)81164-4.
H-protein of the glycine cleavage system has lipoic acid on the Lys59 residue. Comparison of amino acid sequences around the lipoate attachment site of H-proteins from various sources and acyltransferases of alpha-keto acid dehydrogenase complexes indicated that Gly43, Glu56, Glu63 and Gly70 of bovine H-protein are highly conserved among these proteins. Modification of these conserved residues by site-directed mutagenesis indicated that Glu56 and Gly70 are important for the lipoylation of H-protein and suggested that the proper conformation around the lipoic acid attachment site is required for the association of H-protein to the enzyme responsible for the lipoylation.
甘氨酸裂解系统的H蛋白在赖氨酸59残基上有硫辛酸。对来自不同来源的H蛋白的硫辛酸附着位点周围的氨基酸序列与α-酮酸脱氢酶复合物的酰基转移酶进行比较表明，牛H蛋白的甘氨酸43、谷氨酸56、谷氨酸63和甘氨酸70在这些蛋白质中高度保守。通过定点诱变对这些保守残基进行修饰表明，谷氨酸56和甘氨酸70对H蛋白的硫辛酰化很重要，并表明硫辛酸附着位点周围的适当构象是H蛋白与负责硫辛酰化的酶结合所必需的。
