Genomic mining has identifi ed a novel microbial alkaline esterase from the Indian Ocean. This esterase was overexpressed in E. coli BL21（DE3） and further functionally characterized. Under optimal conditions（10 mmo...Genomic mining has identifi ed a novel microbial alkaline esterase from the Indian Ocean. This esterase was overexpressed in E. coli BL21（DE3） and further functionally characterized. Under optimal conditions（10 mmol/L substrate, p H 6.0, 2 h at 40 ℃）, this esterase can hydrolyze racemic methyl mandelate to（ R）-methyl mandelate with very high optical purity（e. e. 〉99%） and yield（nearly 90%）. Interestingly, the stereoselectivity of this esterase is opposite to that of two previously reported lipases that can generate（ S）-methyl mandelate through the hydrolysis of racemic methyl mandelate. No organic solvents or other additives were required to optimize the optical purity and production of the fi nal chiral product（R）-methyl mandelate, which can potentially simplify the production procedure of（ R）-methyl mandelate catalyzed by esterase.展开更多
Let R be a left and right Noetherian ring and n, k be any non-negative integers. R is said to satisfy the Auslander-type condition Gn（k） if the right fiat dimension of the （i ＋ 1）-th term in a minimal injective r...Let R be a left and right Noetherian ring and n, k be any non-negative integers. R is said to satisfy the Auslander-type condition Gn（k） if the right fiat dimension of the （i ＋ 1）-th term in a minimal injective resolution of RR is at most i ＋ k for any 0 ≤ i ≤ n - 1. In this paper, we prove that R is Gn（k） if and only if so is a lower triangular matrix ring of any degree t over R.展开更多
基金Supported by the National Natural Science Foundation of China(No.21302199)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA11030404)+1 种基金the Project of“Engineering HighPerformance Microorganisms for Advanced Bio-Based Manufacturing”from the Chinese Academy of Sciences(No.KGZD-EW-606)the Guangzhou Science and Technology Plan Projects(No.201510010012)
文摘Genomic mining has identifi ed a novel microbial alkaline esterase from the Indian Ocean. This esterase was overexpressed in E. coli BL21（DE3） and further functionally characterized. Under optimal conditions（10 mmol/L substrate, p H 6.0, 2 h at 40 ℃）, this esterase can hydrolyze racemic methyl mandelate to（ R）-methyl mandelate with very high optical purity（e. e. 〉99%） and yield（nearly 90%）. Interestingly, the stereoselectivity of this esterase is opposite to that of two previously reported lipases that can generate（ S）-methyl mandelate through the hydrolysis of racemic methyl mandelate. No organic solvents or other additives were required to optimize the optical purity and production of the fi nal chiral product（R）-methyl mandelate, which can potentially simplify the production procedure of（ R）-methyl mandelate catalyzed by esterase.
基金supported by the Specialized Research Fund for the Doctoral Pro-gram of Higher Education(Grant No.20100091110034)National Natural Science Foundation of China(Grant Nos.11171142,11126169,11101217)+2 种基金Natural Science Foundation of Jiangsu Province of China(Grant Nos.BK2010047,BK2010007)the Scientific Research Fund of Hunan Provincial Education Department(Grant No.10C1143)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Let R be a left and right Noetherian ring and n, k be any non-negative integers. R is said to satisfy the Auslander-type condition Gn（k） if the right fiat dimension of the （i ＋ 1）-th term in a minimal injective resolution of RR is at most i ＋ k for any 0 ≤ i ≤ n - 1. In this paper, we prove that R is Gn（k） if and only if so is a lower triangular matrix ring of any degree t over R.
