Showing papers on "Penicillin amidase published in 1978"

Substrate specificity of penicillin acylase of E. coli

Abstract: The hydrolysis of several phenylacetylamino compounds was studied using a purified preparation of E. coli penicillin acylase. The L-isomers of phenylacetyl amino acids were cleaved much faster than the D-isomers. The same observations was made for some phenylacetylamino beta-lactams. When the beta-lactam ring is incorporated in a penam or cephem ring system, the D-isomers were hydrolysed somewhat faster than the L-isomers. We also confirmed that benzylpenicillins with an hydroxy- or an amino-group in alpha-position of the side chain were hydrolysed, both in the normal and the 6-epi-series.

Production of 6APA in the Penicillin G Fermentation Plant by Using Fiber-Entrapped Penicillin Amidase

Abstract: In the last few years improvements in enzyme immobilization techniques have enabled enzymatic hydrolysis of penicillin G for the production of 6APA to become a viable alternative to chemical hydrolysis. This paper presents a novel process method for producing 6APA by enzymatic hydrolysis. In the overall process penicillin G is separated from the fermented broth by solvent extraction; the end product of the solvent extraction is generally a crude concentrated solution of penicillin G,K from which the penicillin is crystallized by azeotropic distillation with butanol. In the conventional 6APA enzymatic process the dried crystals of penicillin G are dissolved in water, and sent to the hydrolysis stage to yield 6APA and phenyl acetic acid. It would appear that if the 6APA plant was located adjacent to the penicillin fermentation plant, then it would be possible to hydrolyze directly the crude solution of penicillin G obtained from the solvent extraction, by-passing the crystallization stage. In this stage about 8–10% of the penicillin G is lost either in the mother liquor or through degradation during the azeotropic distillation. In addition it should also be possible to recover the phenyl acetic acid, which could be used as a precursor in the penicillin fermentation.

Study of E. coli penicillin amidase. The pH dependence of the equilibrium constant of ampicillin enzymatic hydrolysis

Abstract: The equilibrium parameters of the hydrolysis of ampicillin catalysed by penicillin amidase were determined within the pH range of 4.5 to 5.5. The values of the ionization constants of the carboxy group of D-(-)-ALPHA-AMINOPHENYLACETIC ACID (PK1=1.80) and amino group of 6-aminopenicillanic acid (pK2=4.60) were estimated and pH-dependence of the effective free energy of ampicillin hydrolysis was calculated. It was shown that the thermodynamic optimum of ampicillin synthesis was at 3.20 (the value of the effective free energy under the experimental conditions was 3.27 kcal/mole). The value of the "true", pH-independent free energy of hydrolysis (deltasigma) of the amide bond in the ampicillin molecule was determined to be equal to 9.72 kcal/mole. The thermodynamic parameters of ampicillin and benzylpenicillin hydrolysis were compared. The amino group in the alpha-position of phenylacetic acid was shown to have a significant effect on the values of "true" free energy of hydrolysis of the penicillin amide bond and free ionization energy in the system.