Structure of porcine heart cytoplasmic malate dehydrogenase: combining X-ray diffraction and chemical sequence data in structural studies.
Structure of porcine heart cytoplasmic malate dehydrogenase: combining X-ray diffraction and chemical sequence data in structural studies.
复制标题
猪心脏细胞质苹果酸脱氢酶的结构：在结构研究中结合 X 射线衍射和化学序列数据。
DOI：
10.1021/bi00384a011
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发表时间：
1987
期刊：
影响因子：
2.9
通讯作者：
Banaszak,LJ
中科院分区：
文献类型：
--
作者：
Birktoft,JJ;Bradshaw,RA;Banaszak,LJ
摘要：用x射线晶体学和化学测序相结合的方法测定了细胞质苹果酸脱氢酶（sMDH）的氨基酸序列。最初的分子模型包含了一个“x射线氨基酸序列”，该序列主要来自于以2.5-Á分辨率计算的多重同构替换相电子密度图的评估。在约束最小二乘晶体学改进后，从模型相计算了电子密度差图，并尝试升级x射线氨基酸序列。在x射线结构中寻找肽位置的方法与用于研究蛋白质同源性的方法相似，并且对于大片段是成功的。对于sMDH，即使有部分化学序列数据，x射线方法本身也不足以得出完整的氨基酸序列。然而，对于中等分辨率的相对较大的分子，电子密度图在确定肽片段的线性位置方面有相当大的帮助。sMDH的n -乙酰化多肽链有331个氨基酸，在2.5-Á分辨率的衍射数据下，其晶体学精度为19%。
Revised Manuscript Received November 19, 1986 abstract: The amino acid sequence of cytoplasmic malate dehydrogenase (sMDH) has been determined by a combination of X-raycrystallographic and chemical sequencing methods. The initial molecular model incorporated an “X-ray amino acid sequence” that was derived primarily from an evaluation of a multiple isomorphous replacement phased electron density map calculated at 2.5-Á resolution. Following restrained least-squares crystallographic refinement, difference electron density maps were calculated from model phases, and attempts were made to upgrade the X-ray amino acid sequence. The method used to find the positions of peptides in the X-ray structure was similar to those used for studying protein homology and was shown to be successful for large fragments. For sMDH, X-ray methods by themselves were insufficient to derive a complete amino acid sequence, even with partial chemical sequence data. However, for this relatively large molecule at medium resolution, the electron density maps were of considerable help in determining the linear position of peptide fragments. The N-acetylated polypeptide chain of sMDH has 331 amino acids and has been crystallographically refined to an R factor of 19% for 2.5-Á resolution diffraction data.