The stereoselective hydrolysis of esmolol in whole blood and in its separated components from rat,rabbit and human was investigated.Blood esterase activities were variable in different species in the order of rat>r...The stereoselective hydrolysis of esmolol in whole blood and in its separated components from rat,rabbit and human was investigated.Blood esterase activities were variable in different species in the order of rat>rabbit>human.Rat plasma showed the high esterase activity and had no stereoselectivity to enantiomers.Rabbit red blood cell（RBC） membrane,RBC cytosol and plasma all hydrolyzed esmolol but with different esterase activity,whereas the hydrolysis in RBC membrane and cytosol showed significant stereoselectivity towards R-（+）-esmolol.Esterase in RBC cytosol from human blood mainly contributed to the esmolol hydrolysis,which was demonstrated with no stereoselctivity.Esterase in human plasma showed a low activity,but a remarkable stereoselectivity with R-（+）-esmolol.In addition,the protein concentration affected the hydrolysis behavior of esmolol in RBC suspension.Protein binding of esmolol enantiomers in human plasma,human serum albumin（HSA） and α;-acid glycoprotein（AGP） revealed that there was a significant difference in bound fractions between two enantiomers,especially for AGP.Our results indicated that the stereoselective protein binding might play a role in the different hydrolysis rates of esmolol enantiomers in human plasma.展开更多
Esterases are crucial biocatalysts in chiral compound synthesis.Herein,a novel esterase EstSIT01 belonging to family V was identified from Microbacterium chocolatum SIT101 through genome mining and phylogenetic analys...Esterases are crucial biocatalysts in chiral compound synthesis.Herein,a novel esterase EstSIT01 belonging to family V was identified from Microbacterium chocolatum SIT101 through genome mining and phylogenetic analysis.EstSIT01 demonstrated remarkable efficiency in asymmetrically hydrolyzing meso-dimethyl ester[Dimethyl cis-1,3-Dibenzyl-2-imidazolidine-4,5-dicarboxyate],producing over 99%yield and 99%enantiomeric excess(e.e.)for(4S,5R)-monomethyl ester,a crucial chiral intermediate during the synthesis of d-biotin.Notably,the recombinant E.coli expressing EstSIT01 exhibited over 40-fold higher activity than that of the wild strain.EstSIT01 displays a preference for short-chain p-NP esters.The optimal temperature and pH were 45°C and 10.0,with Km and kcat values of 0.147 mmol/L and 5.808 s−1,respectively.Molecular docking and MD simulations suggest that the high stereoselectivity for meso-diester may attribute to the narrow entrance tunnel and unique binding pocket structure.Collectively,EstSIT01 holds great potential for preparing chiral carboxylic acids and esters.展开更多
基金supported by National Major Projects of Ministry Science and Technology of China(2011CB710800,2012ZX09506001-004)Zhejiang Education Department(Y200909571)
文摘The stereoselective hydrolysis of esmolol in whole blood and in its separated components from rat,rabbit and human was investigated.Blood esterase activities were variable in different species in the order of rat>rabbit>human.Rat plasma showed the high esterase activity and had no stereoselectivity to enantiomers.Rabbit red blood cell（RBC） membrane,RBC cytosol and plasma all hydrolyzed esmolol but with different esterase activity,whereas the hydrolysis in RBC membrane and cytosol showed significant stereoselectivity towards R-（+）-esmolol.Esterase in RBC cytosol from human blood mainly contributed to the esmolol hydrolysis,which was demonstrated with no stereoselctivity.Esterase in human plasma showed a low activity,but a remarkable stereoselectivity with R-（+）-esmolol.In addition,the protein concentration affected the hydrolysis behavior of esmolol in RBC suspension.Protein binding of esmolol enantiomers in human plasma,human serum albumin（HSA） and α;-acid glycoprotein（AGP） revealed that there was a significant difference in bound fractions between two enantiomers,especially for AGP.Our results indicated that the stereoselective protein binding might play a role in the different hydrolysis rates of esmolol enantiomers in human plasma.
基金supported by the Shanghai Committee of Science and Technology(No.13430503400)Project of Leading Talents in Shandong Taishan Industry(Grant No.LJNY202019)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(No.ZX2012-05)Innovation Program of Shanghai Municipal Education Commission(No.11YZ227).
文摘Esterases are crucial biocatalysts in chiral compound synthesis.Herein,a novel esterase EstSIT01 belonging to family V was identified from Microbacterium chocolatum SIT101 through genome mining and phylogenetic analysis.EstSIT01 demonstrated remarkable efficiency in asymmetrically hydrolyzing meso-dimethyl ester[Dimethyl cis-1,3-Dibenzyl-2-imidazolidine-4,5-dicarboxyate],producing over 99%yield and 99%enantiomeric excess(e.e.)for(4S,5R)-monomethyl ester,a crucial chiral intermediate during the synthesis of d-biotin.Notably,the recombinant E.coli expressing EstSIT01 exhibited over 40-fold higher activity than that of the wild strain.EstSIT01 displays a preference for short-chain p-NP esters.The optimal temperature and pH were 45°C and 10.0,with Km and kcat values of 0.147 mmol/L and 5.808 s−1,respectively.Molecular docking and MD simulations suggest that the high stereoselectivity for meso-diester may attribute to the narrow entrance tunnel and unique binding pocket structure.Collectively,EstSIT01 holds great potential for preparing chiral carboxylic acids and esters.
