https://scholars.lib.ntu.edu.tw/handle/123456789/144011
標題: | Crystal structures of human glutaminyl cyclase, an enzyme responsible for protein N-terminal pyroglutamate formation | 作者: | Huang, Kai-Fa Liu, Yi-Liang Cheng, Wei-Ju Ko, Tzu-Ping Wang, Andrew H.-J. |
關鍵字: | Alzheimer's disease; Aminopeptidase; Crystallography; Intramolecular cyclization; Posttranslational modification | 公開日期: | 2005 | 起(迄)頁: | 13117-13122 | 來源出版物: | Proceedings of the National Academy of Sciences | 摘要: | N-terminal pyroglutamate (pGlu) formation from its glutaminyl (or glutamyl) precursor is required in the maturation of numerous bioactive peptides. The aberrant formation of pGlu may be related to several pathological processes, such as osteoporosis and amyloidotic diseases. This N-terminal cyclization reaction, once thought to proceed spontaneously, is greatly facilitated by the enzyme glutaminyl cyclase (QC). To probe this important but poorly understood modification, we present here the structure of human QC in free form and bound to a substrate and three imidazole-derived inhibitors. The structure reveals an α/β scaffold akin to that of two-zinc exopeptidases but with several insertions and deletions, particularly in the active-site region. The relatively closed active site displays alternate conformations due to the different indole orientations of Trp-207, resulting in two substrate (glutamine t-butyl ester)-binding modes. The single zinc ion in the active site is coordinated to three conserved residues and one water molecule, which is replaced by an imidazole nitrogen upon binding of the inhibitors. Together with structural and kinetic analyses of several active-site-mutant enzymes, a catalysis mechanism of the formation of protein N-terminal pGlu is proposed. Our results provide a structural basis for the rational design of inhibitors against QC-associated disorders. ? 2005 by The National Academy of Sciences of the USA. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/163353 | DOI: | 10.1073/pnas.0504184102 | SDG/關鍵字: | acyltransferase; exopeptidase; glutamine; glutaminyl cyclase; imidazole derivative; indole derivative; nitrogen; pyroglutamic acid; tryptophan; unclassified drug; water; zinc ion; alpha chain; Alzheimer disease; amino terminal sequence; amyloidosis; article; beta chain; catalysis; crystal structure; cyclization; enzyme active site; enzyme conformation; enzyme kinetics; enzyme structure; gene deletion; gene insertion; osteoporosis; priority journal; Aminoacyltransferases; Binding Sites; Catalysis; Crystallography, X-Ray; Enzyme Inhibitors; Humans; Imidazoles; Kinetics; Molecular Structure; Mutation; Protein Binding; Protein Structure, Secondary; Water; Zinc |
顯示於: | 生化科學研究所 |
在 IR 系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。