PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “AMIDASES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1997

Allelic variation in Streptococcus pneumoniae autolysin (N-acetyl muramoyl-L-alanine amidase).

The lytA gene encoding the autolysin of Streptococcus pneumoniae may be a virulence determinant. Single-strand conformational polymorphism analysis demonstrated heterogenicity throughout the gene in clinical isolates and strains from the clonal serotypes 7 and 14. Sequence analysis of part of the choline-binding domain showed that in two isolates four amino acid substitutions occurred.

Alleles↗
PubMed1976

[Study of penicillin amidase from E. coli. pH-dependence of kinetic parameters of enzymatic hydrolysis of benzylpenicillin].

The authors studies pH-dependencies of the kinetic parameters (Vm, KM, Vm/KM) and constants of competitive inhibition by phenylacetic acid of penicillinamidase-catalyzed hydrolysis of benzylpenicillin. The experimental data are in agreement with the assumption according to which there are 3 equilibrium ionogenic forms of the enzyme and enzyme-substrate (or enzyme-inhibitor) complexes, i.e. acidic, neutral and alkaline, the neutral form being the only active form of the Michaelis complex. Values of pK in the ionogenic groups controlling interconversions of both the free enzyme (pK1 6.1 and pK2 7.6) and of the enzyme-substrate complex (pKa 6.1 and pK2 10.2 or the enzyzme-inhibitor complex (pK''1 6.1 and pK''2 9.5) were determined. From this and the previously published results it was concluded that the group with pK 6.1 was involved in the catalysis and the group with pK 10.2 in the maintenance of the active conformation of the active centre of penicillinamidase. The ionogenic group with pK 7.6 was apparently involved in the enzyme-substrate binding.

Amidohydrolases↗
PubMed1977

[Penicillin amidase from E. coli. A direct spectrophotometric method of determining the enzyme's activity].

A method for determination of the enzymatic activity of penicillinamidas (PA) based on spectrophotometric estimation of the stained product amount produced in hydrolysis of 4-phenylacetamido-2-nitrobenzoic acid (PANBA) catalyzed by the enzyme is proposed. Some physico-chemical properties of the substrate and the stained product were studied. The kinetic parameters of the PANABA enzymatic hydrolysis were determined. Catalytic activity of some enzyme products of PA of different purity levels was studied comparatively in reactions of PANBA and benzylpenicillin hydrolysis.

Amidohydrolases↗
PubMed1977

[Penicillin amidase from E. coli. Some physicochemical properties of the soluble enzyme].

Homogeneity of the enzyme was shown with the methods of gel filtration and disc electrophoresis. The molecular mass of penicillinamidase (PA) was determined. Sorption of PA by a carboxylic ion exchanger within a wide range of pH was studied. The values of pH in the ion exchanger phase under the conditions of the enzyme sorption were estimated. The ion exchange technique for determination of the isoelectric points of the proteins is described and the isoelectric point of PA is determined. It is proposed to use the method for estimation of close ionization constants of amphoteric an weak electrolites for interpretation of the bell-like pH dependence of kinetic and equilibrium parameters of the enzymatic reaction. The ionization constants of Michaelis complex of PA were evaluated. The activation energy of benzylpenicillin hydrolysis catalized by PA was determined.

Amidohydrolases↗
PubMed1977

[Penicillin amidase from E. coli. Some physicochemical properties of the enzyme incorporated into polyacrylamide gel].

The physico-chemical properties of penicillinamidase (PA) immobilized in polyacrylamide gel (IPA) were investigated. It was shown that simple incorporation of PA into polyacrylamide gel was not effective because of gradual washing out of the enzyme. The use of a complex method for the immobilization (immobilization in the presence of a linking agent) resulted in higher stability of IPA, the choice of the optimal ratio of the reagents being of paramount importance. The mechanical strength of IPA was studied in model experiments.

Acrylamides↗
PubMed1977

[E. coli penicillin amidase. Physico-chemical properties of the enzyme covalently bound to the 2-(3'-amino-4'-methoxyphenyl)-sulfonylethyl ester of cellulose].

The effect of the procedure of the enzyme binding with the carrier on the properties of the heterogenous catalyst obtained by covalent binding of penicillinamidase (PA) with cellulose 2-(3'-amino-4'-methoxyphenyl)-sulphonylethyl ether by means of the bifunctional reagent, i.e. glutaric aldehyde was studied. It was shown that the amount of the bound enzyme increased with a rise in the amount of the enzyme taken for the binding, while the binding efficiency characterizing the part of the active enzyme in the total amount of the bound PA decreased practically 2 times. The use of the enzyme preparations with different purify levels for the binding provided differentiation of the effects resulting in the activity loss on immobilization. In other words it provided separate estimation of the inactivation effect of the matrix and the immobilization procedure, as well as the interaction of the enzyme molecules with each other and other protein molecules.

Amidohydrolases↗
PubMed1989

[Study of amino acid utilization by isogenic strains of Escherichia coli in relation to the culture growth and biosynthesis of penicillin amidase].

Dynamics of free amino acid utilization by isogenic strains of Escherichia coli differing in intensity of their growth and levels of penicillin acylase biosynthesis in media containing corn steep liquor or peptone was studied. It was shown that in both the media some amino acids such as serine, threonine, glutaminic and asparaginic acids were actively utilized by the strains mainly during the culture intensive growth while others such as glycine, alanine and tyrosine were actively utilized during the enzyme biosynthesis. Intensively utilized arginine and proline were probably used for the growth and biosynthesis. The other amino acids were not utilized completely from the media. The lowest levels of their utilization were observed when the strains were cultivated in the medium with peptone.

Amidohydrolases↗