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At least 433 records · Page 24Linked to original sources
PubMed1975

[Properties of penicillin amidase covalently bound to cellulose matrices].

Properties of penicillinamidase (PA) covalently bound with the cellulose matrix were studied. The efficiency of the binding depended on the bind type and purity of the native enzyme taken for binding. Stability of the immobilized PA (IPA) was studied at wide pH ranges. The effect of the ion strength, substrate concentration and purity of the native PA on stability of IPA was also investigated. The maximum stability of the enzyme was observed at pH 6.5-7.0 Stability of IPA depended on the purity of the native enzyme. When PA of the diazotized ether of cellulose containing amino groups was used, the enzyme was destabilized. IPA prepared on chlortriazinylcellulose was more stable than the respective native PA almost by I order.

Amidohydrolases↗
PubMed1980

[Penicillin amidase from E. coli. The kinetic and equilibrium parameters of the enzymatic hydrolysis of 7-phenylacetamidodesacetoxycephalosporanic acid catalyzed by an immobile enzyme].

The kinetics of 7-phenylacetamidodesacetoxycephalosporanic acid (7-PADCA) catalyzed by immobilized penicillinamidase was studied. The kinetic and equilibrium parameters of the reaction were determined by analysis of the kinetic curves of the reaction product accumulation. Inhibition of the enzymatic reaction by the substrate and hydrolysis products was studied. It was found that the Michaelis complex completely lost its activity after attachment of the substrate second molecule to it. The values of the Michaelis constants, catalytic constant and constants of inhibition by the substrate and reaction products were determined: Km = (9.3 +/- 1.1) . 10(-5) M, kcat = (65 +/- 5) c-1, Ks = (1.4 +/- 0.1) . 10(-2) M, K1 (FAA) = (2.5 +/- 0.3) . 10(-4) M, K1 (7-ADCA) = (1.4 +/- 0.1) . 10(-1) M. The diffusion effect in the kinetic reaction catalyzed by immobilized penicillinamidase is discussed. The values of the Thiele modulus and the actual value of Km were calculated.

Amidohydrolases↗
PubMed1980

[Penicillin amidase from E. coli. The determination of the ionization constants of the Michaelis complex ionogenic groups in the enzymatic deacylation reactions of the phenacetyl derivatives of phenylglycine and 7-aminodesacetoxychephalosporanic acid].

pH and temperature relationships of the maximum rate of the reaction of enzymatic hydrolysis of phenacetyl derivatives of phenylglycine (PPG) and 7-aminodesacetoxycephalosporanic acid (7-PADCA) catalysed by immobilized penicillinamidase (IPA) (penicillinamidohydrolase CE 3.5.1.11) were studied. A possibility of applying for the routine methods used in determination of electrochemical properties of ampholites for estimation of the ionization constants of the functional groups of both the enzyme and the enzyme-substrate complex was shown. The applicability of various methods for estimation of the ionization constants is discussed and the ways of determination of the ionization constants and the means of quantitative description of the bell-like pH relationship of the kinetic and equilibrium parameters of the biocatalytic reaction are presented. The equations described were used in analysis of the pH relationship of the immobilized penicillinamidase enzymatic activity in the reactions of 7-PADCA and L-PPG hydrolysis. The estimated ionization constants of the ionogenic groups of the Michaelis complexes were used in quantitative description of the electrochemical state of the complexes at wide pH ranges. The acid properties of the PA and IPA complexes with a number of substrates, such as benzylpenicillin, 7-PADCA, L-PPG and PANAB were compared. The effect of the immobilization procedure, electrochemical properties of the substrates and the reaction products on the electrochemical state of the Michaelis complexes is discussed.

Acylation↗
PubMed1981

[E. coli penicillin amidase. Methods for estimating the close ionization constants of ionogenic groups of the enzyme complex with substrates containing free amino groups].

The possible use of various procedures for estimation of the ionization constants of the Michaelis complex by the pH dependence of the maximum enzymatic reaction rate is discussed. It is shown that the procedures described in the literature for estimation of the close ionization constants of the enzyme-substrate complexes have limitations and in some cases cannot be used. The paper presents the methods for estimation of the constants and means for quantitative description of the bell-shaped pH dependence of the kinetic and equilibrium parameters of the biocatalytic reaction. The equations recommended in the paper were used in analysis of the pH dependences of the maximum rate of the reactions during the enzymatic synthesis of cefalexin catalysed with immobilized penicillinamidase (IPA) (CE 3.5. 1.11). The ionization constants of the enzyme-substrate complexes of IPA were compared during hydrolysis and synthesis of the compounds acylated with phenylacetic and aminophenylacetic acids. The effect of the nature of the leaving substrate group and added nucleophilic gent on the electrochemical state of the Michaelis complex is discussed.

Amidohydrolases↗
PubMed1994

Amidase activity of human Bence Jones proteins.

Bence Jones proteins purified from urine of patients with multiple myeloma were found to be capable of hydrolyzing carbobenzoxy-L-valyl-glycyl-L-arginine p-nitroanilide (Chromozym TRY) and benzoyl-L-arginine p-nitroanilide (BApNA), synthetic chromogenic substrates for trypsin. The amidolytic activity obeyed classic Michaelis-Menten kinetics, exhibiting optimal activity around pH 8.4 and apparent Km of 140-730 microM and 18-27 microM for Chromozym TRY and BApNA, respectively. No activity was detected with intact IgG or Fab fragment, whereas the activity comparable to those of Bence Jones proteins was found with light chain derived from inactive IgG. Several lines of circumstantial evidence indicate that the observed activity was not due to contaminating enzyme.

Amidohydrolases↗
PubMed2005

delta-(D -alpha-Aminoadipoyl)-cleaving amidase of Ochrobactrum anthropi.

Ochrobactrum anthropi cleaved the delta-(D-alpha-aminoadipoyl)-side chain from delta-(D-alpha-aminoadipoyl)-7-amino-4-methylcoumarin, a beta-lactamase-resistant cephalosporin C analogue. In whole cell conversions up to 1 nkat g(-1) dry cell wt were achieved. O. anthropi possesses also gamma-D-glutamyltranspeptidase activity, 8 nkat g(-1) dry cell wt, the likely cause of delta-(D-alpha-aminoadipoyl)-cleavage.

2-Aminoadipic Acid↗