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Recombinant Candida antarctica lipase B (rCALB) expressed in methylotrophic yeast, Pichia pastoris was covalently immobilized on epoxy-activated macroporous poly(glycidyl methacrylate-ter-divinyl benzene-ter-ethylene dimethacrylate) beads, namely DILBEADS™TA with activity recovery of 39.2%. Tributyrin hydrolysis activity (TBU) of the optimum immobilized enzyme catalyst DILBEADSCB10K was 3380.4 TBU/g dry beads, which is approximately 1.5 times that of Novozym 435 (2592.92 TBU/g dry beads) under similar conditions of TBU activity analysis. Though, the optimum pH for both free as well as immobilized enzyme was found to be 7.0 and optimum temperature was found to be 37°C, the immobilized enzyme catalyst DILBEADSCB10K showed better stability over the pH ranges from 3 to 6 as well as 8 to 10. At extreme acidic and basic pH values, activity of DILBEADSCB10K was 3% more than that of free rCALB enzyme. After 1 h incubation at 50°C, the activity of DILBEADSCB10K was 9% more than that of free rCALB. The impr...

Beta-lactam acylase enzyme producers were isolated from soil samples. Soil samples were induced with phenyl amino acid derivatives for selelctive isolation. Out of the two potential isolates obtained, one of the isolates was studied for presence of beta-lactam acylase enzyme with cephalexin as model substrate. Enzyme activity of isolate grown in media at varying pH showed it to be tolerant to alkaline pH 8.5. Also the substrate specificity for various cephalosporins showed it most selective to cephalexin.

Penicillin G acylase from Achromobacter sp. (NPGA) was studied in the enzymatic synthesis of β-lactam antibiotics by kinetically controlled N-acylation. When compared with penicillin acylase of Escherichia coli (PGA), the NPGA was significantly more efficient at syntheses of ampicillin and amoxicillin (higher S/H ratio and product accumulation) in the whole range of substrate concentrations. The degree of conversion of 6-aminopenicillanic acid to amoxicillin and ampicillin (160 mM 6-APA, 350 mM acyl donor methylester[Symbol: see text]HCl, pH 6.3, 25 °C, reaction time of 200 min) with immobilized NPGA equaled 96.9 % and 91.1 %, respectively. The enzyme was highly thermostable with maximum activity at 60 °C (pH 8.0) and 65 °C (pH 6.0). Activity half-life at 60 °C (pH 8.0) and at 60 °C (pH 6.0) was 24 min and 6.9 h, respectively. Immobilized NPGA exhibited long operational stability with half-life of about 2,000 cycles for synthesis of amoxicillin at conversion conditions used in large-scale processes (230 mM 6-APA, 340 mM D-4-hydroxyphenylglycine methylester[Symbol: see text]HCl, 27.5 °C, pH 6.25). We discuss our results with literature data available for related penicillin acylases in terms of their industrial potential.