title: Enhancement of ethyl propionate synthesis by poly (AAc-co-HPMA-cl-MBAm)-immobilized Pseudomonas aeruginosa MTCC-4713, exposed to Hg2+ and NH4+ ions.
abstract: A purified alkaline thermo-tolerant bacterial lipase from Pseudomonas aeruginosa MTCC-4713 was immobilized on a poly (AAc-co-HPMA-cl-MBAm) hydrogel. The hydrogel-bound lipase achieved 93.6% esterification of ethanol and propionic acid (300 mM: 100 mM) into ethyl propionate at temperature 65 degrees C in 3 h in the presence of a molecular sieve (3 angstroms). In contrast, hydrogel-immobilized lipase pre-exposed to 5 mM of HgCl2 orNH4Cl resulted in approximately 97% conversion of reactants in 3 h into ethyl propionate under identical conditions. The salt-exposed hydrogel was relatively more efficient in repetitive esterification than the hydrogel-bound lipase not exposed to any of the cations. Moreover, bound lipase exposed Hg2+ or NH4+ ions showed altered specificity towards p-nitrophenyl esters and was more hydrolytic towards higher C-chain p-nitrophenyl esters (p-nitrophenyl laurate and p-nitrophenyl palmitate with C 12 and C 16 chain) than the immobilized lipase not exposed to any of the salts. The later showed greater specificity towards p-nitrophenyl caprylate (C 8).
authors.affiliation: Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla-171 005, India. kanwarss2000@yahoo.com
authors.forename: S S
authors.initials: SS
authors.lastname: Kanwar
authors.forename: H K
authors.initials: HK
authors.lastname: Verma
authors.forename: S
authors.initials: S
authors.lastname: Pathak
authors.forename: R K
authors.initials: RK
authors.lastname: Kaushal
authors.forename: Y
authors.initials: Y
authors.lastname: Kumar
authors.forename: M L
authors.initials: ML
authors.lastname: Verma
authors.forename: S S
authors.initials: SS
authors.lastname: Chimni
authors.forename: G S
authors.initials: GS
authors.lastname: Chauhan
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000179:Acrylates / Q000737:chemistry; D002412:Cations; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D020100:Hydrogels / Q000737:chemistry; D008049:Lipase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008628:Mercury / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D011422:Propionates / Q000138:chemical synthesis* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D000178:Acrylamides; D000179:Acrylates; D002412:Cations; D004800:Enzymes, Immobilized; D020100:Hydrogels; D008689:Methacrylates; D011422:Propionates; D000644:Quaternary Ammonium Compounds; C069373:ethyl propionate; D008049:Lipase; C021221:N,N'-methylenebisacrylamide; D008628:Mercury; C032802:hydroxypropyl methacrylate