Esterase is widely distributed in animals,plants,and microorganisms.It has wide substrate spe-cificity and can catalyze hydrolysis and synthesis of a variety of compounds containing esters,amides,sul-fones,or acetyl groups.Esterase has important applications in the field of biocatalysis.This paper studies the extraction of the enzymology of esterase from pig liver,and its ability to catalyze the deacetylation of 7-aminocephalosporanic acid to produce deacetyl-7-aminocephalosporanic acid.The main results are as follows:Extraction of esterase from pig liver by three-phase partitioning has been established.The effects of different organic solvents,organic solvents dosage,ammonium sulfate concentration,and the pH of the system and extraction temperature on the three-phase extraction of pig liver esterase have been investigated.The experimental results showed that under the conditions of ammonium sulfate mass frac-tion 45％,isobutanol to water ratio of 1∶1,pH 7.0,and temperature 30 ℃,the enzyme activity recovery rate was 65.79％,and the purification factor was 2.31.With pig liver esterase as a catalyst,the prepara-tion of D-7-ACA by deacetylation of 7-ACA was studied.The conversion rate of 7-ACA reached 94.33％when the preparation conditions were pH 7.5,temperature 35 ℃,substrate concentration 2％ and en-zyme addition was 30 U/mL.
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