Rat brain hexokinase: amino acid sequence at the substrate hexose binding site is homologous to that of yeast hexokinase.
Rat brain hexokinase: amino acid sequence at the substrate hexose binding site is homologous to that of yeast hexokinase.
复制标题
大鼠脑己糖激酶：底物己糖结合位点的氨基酸序列与酵母己糖激酶的氨基酸序列同源。
DOI：
10.1016/0003-9861(87)90536-4
复制
发表时间：
1987
影响因子：
3.9
通讯作者：
Wilson,JE
中科院分区：
文献类型：
--
作者：
Schirch,DM;Wilson,JE
最近使用反应性 Glc 类似物 N-（溴乙酰基）-d-葡萄糖胺 (GlcNBrAc)（D. M. Schirch 和 J. E. Wilson (1987)Arch. Biochem. Biophys.254, 385–396）来标记大鼠脑 I 型己糖激酶的 Glc 结合位点。该位点位于酶 C 末端的 40 kDa 结构域中，先前显示为底物 ATP 结合位点的位置（M. Nemat-Gorgani 和 J. E. Wilson (1986)Arch. Biochem. Biophys.251, 97–103）。在本研究中，经放射性标记的 GlcNBrAc 修饰的己糖激酶的肽图谱产生了三种标记肽（肽 I-III）。肽 I 和 III 以及催化活性在与 GlcNBrAc 反应期间通过包含 Glc 或 GlcNAc 得到保护。这两种肽与酵母己糖激酶同工酶 A 和 B 序列中的连续区域显示出相当大的同源性。根据 Steitz 及其同事的 X 射线晶体学工作，肽 III 与位于酵母己糖激酶 Glc 结合位点附近的序列同源；肽 I 与酵母己糖激酶的紧邻（朝向 C 末端）区域同源。与 Glc 与酵母酶结合有关的必需丝氨酸残基在大鼠脑己糖激酶的肽 III 中也得到了保守。这些结果有力地支持了哺乳动物 I 型己糖激酶 C 末端的“催化结构域”与酵母己糖激酶具有共同祖先的观点。肽 II 似乎被 GlcNBrAc 非特异性标记，因为标记对保护性配体（例如 Glc 或 GlcNAc）的存在不敏感；肽 II 的序列与酵母同工酶没有可检测到的同源性。
A reactive Glc analog,N-(bromoacetyl)-d-glucosamine (GlcNBrAc), has recently been used (D. M. Schirch and J. E. Wilson (1987)Arch. Biochem. Biophys.254, 385–396) to label the Glc binding site of rat brain Type I hexokinase. This site has been located in a 40-kDa domain at the C-terminus of the enzyme previously shown to be the location of the substrate ATP binding site (M. Nemat-Gorgani and J. E. Wilson (1986)Arch. Biochem. Biophys.251, 97–103). In the present study, peptide mapping of hexokinase modified by radiolabeled GlcNBrAc yields three labeled peptides (Peptides I–III). Peptides I and III, as well as catalytic activity, are protected by inclusion of Glc or GlcNAc during reaction with GlcNBrAc. These two peptides show considerable homology to contiguous regions in the sequences of yeast hexokinase isozymes A and B. Peptide III is homologous to a sequence which, based on the X-ray crystallographic work by Steitz and co-workers, is located near the Glc binding site of yeast hexokinase; Peptide I is homologous to an immediately adjacent (toward the C-terminus) region of yeast hexokinase. An essential serine residue implicated in the binding of Glc to the yeast enzyme is also conserved in Peptide III from rat brain hexokinase. These results provide strong support for the view that the “catalytic domain” at the C-terminus of the mammalian Type I hexokinase shares a common ancestry with yeast hexokinase. Peptide II appears to be nonspecifically labeled by GlcNBrAc since labeling is insensitive to the presence of protective ligands such as Glc or GlcNAc; the sequence of Peptide II shows no detectable homology with the yeast isozymes.