Structural Characterization and Function Determination of a Nonspecific Carboxylate Esterase from the Amidohydrolase Superfamily with a Promiscuous Ability To Hydrolyze Methylphosphonate Esters
摘要:
The uncharacterized protein Rsp3690 from Rhodobacter sphaeroides is a member of the amidohydrolase superfamily of enzymes. In this investigation the gene for Rsp3690 was expressed in Escherichia coli and purified to homogeneity, and the three-dimensional structure was determined to a resolution of 1.8 angstrom. The protein folds as a distorted (beta/alpha)(8)-barrel, and the subunits associate as a homotetramer. The active site is localized to the C-terminal end of the beta-barrel and is highlighted by the formation of a binuclear metal center with two manganese ions that are bridged by Glu-175 and hydroxide. The remaining ligands to the metal center include His-32, His-34, His-207, His-236, and Asp-302. Rsp3690 was shown to catalyze the hydrolysis of a wide variety of carboxylate esters, in addition to organophosphate and organophosphonate esters. The best carboxylate ester substrates identified for Rsp3690 included 2-naphthyl acetate (k(cat)/K-m = 1.0 x 10(5) M-1 s(-1)), 2-naphthyl propionate (k(cat)/K-m = 1.5 x 10(5) M-1 s(-1)), 1-naphthyl acetate (k(cat)/K-m = 7.5 x 10(3) M-1 s(-1)), 4-methylumbelliferyl acetate (k(cat)/K-m = 2.7 x 10(3) M-1 s(-1)), 4-nitrophenyl acetate (k(cat)/K-m = 2.3 x 10(5) M-1 s(-1)), and 4-nitrophenyl butyrate (k(cat)/K-m = 8.8 x 10(5) M-1 s(-1)). The best organophosphonate ester substrates included ethyl 4-nitrophenyl methylphosphonate (k(cat)/K-m = 3.8 x 10(5) M-1 s(-1)) and isobutyl 4-nitrophenyl methylphosphonate (k(cat)/K-m = 1.1 x 10(4) M-1 s(-1)). The (S-p)-enantiomer of isobutyl 4-nitrophenyl methylphosphonate was hydrolyzed 10 times faster than the less toxic (R-p)-enantiomer. The high inherent catalytic activity of Rsp3690 for the hydrolysis of the toxic enantiomer of methylphosphonate esters make this enzyme an attractive target for directed evolution investigations.
[EN] EMS ANALOGUES OF LYN/SRC-TYROSINE KINASE INHIBITORS<br/>[FR] ANALOGUES EMS D'INHIBITEURS DE LYN-SRC-TYROSINE KINASE
申请人:COMBS COLIN
公开号:WO2017100703A1
公开(公告)日:2017-06-15
Embodiments of the present invention are directed to compounds of the formula API―LG―ESM wherein "API" is a monovalent substituent group of an enzyme inhibitor; "LG" is a divalent substituent group of a linking group; and "ESM" is a monovalent substituent group of an esterase sensitive motif; or a pharmaceutically acceptable salt thereof. Other embodiments are directed to methods for using compounds of the formula API―LG―ESM to treat a number of medical conditions, including Alzheimer's disease.
The present application relates to encapsulates, compositions, products comprising such encapsulates, and processes for making and using such encapsulates. Such encapsulates comprise a core comprising a perfume and a shell that encapsulates said core, such encapsulates may optionally comprise a parametric balancing agent, such shell comprising one or more azobenzene moieties.
Acylation of phenols to phenolic esters with organic salts
作者:Zhanrong Zhang、Ziwei Zhao、Mingyang Liu、Huizhen Liu、Qian Li、Junfeng Xiang、Tianbin Wu、Buxing Han
DOI:10.1039/d2gc03807b
日期:——
attractive. Herein, we report an efficient, convenient one-pot method for selective O-acylation of phenols at room temperature in air. For the first time, abundant, safe, stable organic salts are used as acylatingreagents. The reaction was mediated by diethylaminosulfur trifluoride (DAST) which simultaneously acted as an activator for phenols and deoxyfluorination reagent for organic salts. Phenolic esters
A composition, test device and method for determining the presence of leukocytes, esterase and/or esterase activity in a test sample is disclosed. The composition comprises an ester which, when cleaved by esterolytic activity, produces a detectable response such as color formation. In addition the composition comprises the compound 3-quinuclidinol. The device is prepared by incorporating a carrier matrix, such as paper, with the composition. The method comprises contacting a test sample with the device and observing a detectable response.
The invention relates to the use of iron chelating agents, particularly, deferoxamine, in connection with the synergistic treatment of cancer, especially for the treatment of leukemia, with cytostatically effective preparations and for the prevention or mitigation of side effects which are caused by cytostatics.