Enzymatic Promiscuity： Escherichia coli BioH Esterase-catalysed Aldol Reaction and Knoevenagel Reaction

Esterase BioH,which is obligatory for biotin synthesis in Escherichia coli,was found to exhibit a promiscuous ability to catalyse Aldol and Knoevenagel reactions with moderate to good yields.The reaction conditions including organic solvent,molar ratio of ketone to aldehyde,enzyme amount,and reaction time were investigated to evaluate the effect of different reaction conditions on yield.Target compounds were afforded in the best yield of 91.2％ for Aldol reaction and 54.7％ for Knoevenagel reaction.In addition,because the enzyme could be prepared with a low cost,this protocol could provide an economic route to conduct Aldol and Knoevenagel reactions,which expand the field of enzymatic promiscuity.

Enzymatic Promiscuity： ＂Amano＂ Lipase AS-catalysed Synthesis of Naphthopyran Derivatives in Anhydrous Media

＂Amano＂ lipase AS（lipase from Aspergillus niger）, which naturally hydrolyzes triglycerides, was found promiscuously to catalyze multi-component reactions of aromatic aldehydes with malononitrile and β-naphthol to prepare naphthopyran derivatives in anhydrous organic solvents in moderate to good yields.

Enzyme-catalyzed asymmetric domino aza-Michael/aldol reaction for the synthesis of 1,2-dihydroquinolines using pepsin from porcine gastric mucosa

An unprecedented enzyme-catalyzed asymmetric domino aza-Michael/aldol reaction of 2-aminobenzaldehyde and a,b-unsaturated aldehydes is achieved. Pepsin from porcine gastric mucosa provided mild and efficient access to diverse substituted 1,2-dihydroquinolines in yields of 38%–97% with 6%–24%enantiomeric excess（ee）. This work not only provides a novel method for the synthesis of dihydroquinoline derivatives, but also promotes the development of enzyme catalytic promiscuity.

Advances in photo-enzymatic-coupling catalysis system

Photosynthesis,as an efficient pathway for solar energy capture and utilization,has supported aerobionts for billions of years.The imitation of photosynthesis to construct artificial photo-enzymatic-coupling catalysis system has become a pow-erful means to solve energy and environmental problems.After years of in-depth research on this coupled system,through ingenious and rational design,the synergistic effect of photo-and enzymatic catalyses has played a significant role in many different fields,including solar-driven fuel production,chiral chemical synthesis and carbon dioxide fixation.Furthermore,light in enzymatic catalysis could also endow enzyme new possibilities.Photo-induced radical cofactor could bring catalytic promiscuity to enzymes,making them catalyze reactions that natural enzymes cannot.This review summarizes the advances in photo-enzymatic-coupling catalysis system and introduces its essential components,their integration and application.The possibilities presented by photo-induced catalytic promiscuity and its significance for expanding the toolbox of enzymes are also discussed.

Consecutive Methylation Catalyzed by TsrM,an Atypical Class B Radical SAM Methylase

TsrM is a cobalamin-dependent radical S-adenosylmethionine(SAM)methyltransferase belonging to the Class B radical SAM methylase(RSM)family.This enzyme catalyzes the C-2 methylation of L-tryptophan to produce 2-methyltrytophan(2-MeTrp),an intermediate involved in the biosynthesis of thiostrepton A.In this work,we report characterization of an unexpected activity of TsrM,which carries out an additional methylation reaction on the product 2-MeTrp.A series of isotopic labeling studies and assays with different Trp analogs revealed that TsrM is able to transfer a methyl group from SAM to the C4 of 2-MeTrp to produce 2,4-dimethyltryptophan.These results reveal the intriguing substrate specificity of TsrM,further expanding the reaction promiscuity of the radical SAM superfamily enzymes.

‘‘Amano'' lipase DF-catalyzed efficient synthesis of 2,20-arylmethylene dicyclohexane-1,3-dione derivatives in anhydrous media

A simple and efficient method was developed for the synthesis of 2.2＇-arylmethylene dicyclohexane-1,3- dione derivatives via the Knoevenagel-Michael cascade reactions of aromatic aldehydes and 1,3-cyclic diketones catalyzed by ＂Amano＂ lipase DF, which expands the application field of enzyme catalytic promiscuity. This protocol provides several advantages over the traditional chemical synthesis, such as simple work-up procedure, high yields Cup to 94%） and environmental friendliness.

Improvement of saccharification of native grass,Pennisetum sp.using cellulase from isolated Aspergillus fumigatus for bioethanol production:an insight into in silico molecular modelling,docking and dynamics studies

Lignocellulosic grass biomass is potential substrate for economical and sustainable bioethanol production.However,the processing cost of bioethanol that majorly includes the hydrolysis of cellulose by cellulases is still a major concern for its industrial production.Thus,knowledge on the sequence to the structural study of cellulase enzyme with consideration of its catalytic region can give important information for effective enzyme engineering and consequently towards enhanced bioethanol production from Pennisetum sp.Therefore,in this study,sequence conservativeness of different cellulosic site among a group of endoglucanase family of cellulase from previously isolated Aspergillus species has been determined.Furthermore,comparative molecular modeling of the endoglucanase from eight different Aspergillus species including Aspergillus fumigatus was conducted and the obtained structures revealed a high degree of difference in their conformational folds.Analysis from InterProScan revealed that the modeled endoglucanase has similar types of domains and share homology with protein family,such as glycoside hydrolase family-61 and fungal cellulose binding domain.Furthermore,molecular docking and interaction studies demonstrated the presence of residues in the endoglucanase of A.fumigatus viz.His20,His88,Asp96,Ala99,Ser100,Ser101,His102,His169,Glu170,Arg173,Glu178,and Tyr218 that are responsible in forming the substrate interaction.An interesting molecular phenomenon,i.e.,catalytic promiscuity has been noted for all the substrate bound complexes of A.fumigatus endoglucanase which also depicts the degree of ligand binding efficacy of the studied enzyme.The molecular interaction study,binding energy analysis and molecular dynamics simulation,demonstrated that heteromeric substrate XylGlc3 is more strongly interacting with the receptor enzyme.Overall,the present findings revealed that important amino acid residues can help in increasing the specificity of endoglucanase from A.fumigatus towards hydrolysis of Pennisetum sp.and other biomass that has an adequate amount of XylGlc3,for possible industrial applications.