Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0267964 (PAA)
 2,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fermentation parameters for the production of penicillin G acylase by Escherichia coli NCIM 2400 have been evaluated. The bacterium produced the enzyme intracellularly when grown in nutrient broth containing PAA. PAA stimulated the enzyme synthesis by 8-10 fold and reduced the lag period. The optimum concentration of PAA for induction was 20 mM and addition of PAA prior to inoculation gave maximum production of PGA. Glucose, lactose, sorbitol, acetate and lactate even at 0.1% concentration catabolically repressed the enzyme formation. Peptone was the best utilised 'N' source for the enzyme production. Phosphate and yeast extract were found to be essential for both the growth and for enzyme biosynthesis. Temperature between 22-24 degrees C was optimum and under ideal condition E. coli NCIM 2400 produced 0.45-0.55 U/ml of penicillin G acylase.
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PMID:Biosynthesis of benzylpenicillin acylase by Escherichia coli NCIM-2400. 269 12

The possibility of using the multicompartment immobilized enzyme reactor (MIER) in presence of a charged substrate is here explored. Penicillin G acylase is used to convert penicillin G (a free acid, with a pK of 2.6) into two charged products: phenyl acetic acid (PAA, with a pK of 4.2) and 6-aminopenicillanic acid (6-APA, a zwitterion with a pI of 3.6). The enzyme is trapped by an isoelectric mechanism in a chamber of the electrolyzer delimited by a pI 5.0 and a pI 9.0 amphoteric, isoelectric membranes. Under normal operating conditions (continuous substrate feeding in the presence of an electric field), only a low substrate conversion can be achieved, due to rapid electrophoretic transport of unreacted penicillin G out of the reaction chamber towards the anode. Excellent conversion rates (>96%) are obtained under a "doubly-discontinuous" operation mode: a time-lapse substrate feeding, accompanied by short times (4-8 min) of electric field interruption. The product of interest (6-APA, a precursor of semisynthetic penicillins), by virtue of its amphoteric nature, is trapped in a chamber delimited by a pI 3.5 membrane and a pI 5.5 membrane, adjacent to the reaction chamber on its anodic side. The other contaminant product (PAA) first accumulates in the same chamber and then progressively vacates it to collect in the anodic reservoir, leaving behind a pure 6-APA solution. In this operation mode, vanishing amounts of unreacted substrate (penicillin G) leave the reaction chamber to contaminate the adjacent, anodic chambers. A novel class of zwitterionic buffers is additionally reported, able to cover very thoroughly any pH value along the pH 3-10 interval: polymeric, zwitterionic buffers, synthesized with the principle of the Immobiline (acrylamido weak acids and bases) chemicals. Enhanced enzyme reactivity is found in this macromolecular buffers as compared to conventional ones.
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PMID:Electrically immobilized enzyme reactors: bioconversion of a charged substrate. Hydrolysis Of penicillin G by penicillin G acylase. 1039 77

The gene (pac) encoding beta-lactam acylase from Bacillus badius was cloned and expressed in Escherichia coli. The pac gene was identified by polymerase chain reaction (PCR) using degenerated primers, on the basis of conserved amino acid residues. By using single specific primer PCR (SSP-PCR) and direct genome sequencing, a complete pac gene with its promoter region was obtained. The ORF consisted of 2415 bp and the deduced amino acid sequence indicated that the enzyme is synthesized as a preproenzyme with a signal sequence, an alpha-subunit, a spacer peptide and a beta-subunit. The pac gene was expressed with its own promoter in different E. coli host strains and a maximum recombinant PAC (1820 U l(-1)) was obtained in E. coli DH5alpha. The recombinant PAC was purified by Ni-NTA chromatography and the purified PAC had two subunits with apparent molecular masses of 25 and 62 kDa. This enzyme exhibited a high thermostability with a maximum activity at 50 degrees C. This enzyme showed stability over a wide pH range (pH 6.0-8.5) with a maximum activity at pH 7.0 and activity on a wide beta-lactam substrate range. The K(m) values obtained for the hydrolysis of penicillin G and a chromogenic substrate, 6-nitro-3-phenylacetylamidobenzoic acid, from B. badius PAC were 39 and 41 microM, respectively. The PAC activity was competitively inhibited by PAA (K(i), 108 microM) and noncompetitively by 6-APA (K(i), 17 mM). The constitutive production of B. badius PAC in E. coli and its easier purification together with the advantageous properties, such as thermostability, pH stability and broad substrate specificity, make this as a novel enzyme suitable for beta-lactam industry.
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PMID:Molecular cloning and characterization of thermostable beta-lactam acylase with broad substrate specificity from Bacillus badius. 1760 62