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Biomedical subjects

A V Bolobova

Publications and source records attributed to A V Bolobova.

6 recordsLinked to original sources
PubMed2002

The structure and mechanism of action of cellulolytic enzymes.

The modern structural classification of polysaccharases comprising cellulase-hemicellulase enzyme systems is discussed. Their catalytic domains are currently grouped into 15 of more than 80 known glycosyl hydrolase families, whereas substrate binding domains fall into 13 families. The structures of catalytic and substrate binding domains, as well as linker sequences, are briefly considered. A hypothetical mechanism of concerted action of catalytic and substrate binding domains of cellobiohydrolases on the surface of highly ordered cellulose is suggested.

Amino Acid Sequence↗
PubMed1985

The activation of cellulases from different sources by actin.

Actin has been shown to be a potent activator of the enzymatic hydrolysis of cellulose, its addition to the reaction mixture leading to an increase in the hydrolysis rate of up to 6-7 fold. The action of actin is directed primarily towards endoglucanases of cellulase complexes. The degree of activation varies in relation to the cellulases from different microbial sources. The activation of the enzymatic hydrolysis of an insoluble cellulose by actin does not affect the Michaelis constant but increases the maximum velocity of the reaction. Increasing the actin concentration leads to a linear increase in the activation effect which indicates a rather poor binding of actin with the cellulases under study.

Actins↗
PubMedDate not supplied

[Cellulases from microorganisms].

Compositions of cellulase-hemicellulase systems of aerobic fungi (hyphomycetes, ascomycetes, and basidiomycetes), aerobic bacteria, actinomycetes, as well as anaerobic fungi and bacteria, are considered in the context of modern structural classification of glycosyl hydrolases. A new nomenclature of cellulases and relative enzymes based on their structural classification is reviewed. Some opportunities of cellulase improvement by means of protein engineering are discussed.

Bacteria, Aerobic↗
PubMedDate not supplied

[Decomposition of natural aromatic structures and xenobiotics by fungi].

The review deals with transformation of natural and synthetic aromatic compounds by fungi (causative agents of white rot, brown rot, or soft rot, as well as soil filamentous fungi). Major enzyme types involved in the transformation of lignin and aromatic xenobiotics are discussed, with emphasis on activity regulation under the conditions of secondary metabolism and oxidative stress. Coupling of systems degrading polysaccharides/lignin and non-phenolic lignin structures (without the involvement of lignin peroxidase) is analyzed, together with non-enzymatic mechanisms (involving lipoperoxide free radicals, cation-radicals, quinoid mediators, or transition metal ions). Metabolic pathways resulting in the formation of aromatic and haloaromatic compounds in fungi are described. Consideration is given to the mechanisms of fungal adaptation to aromatic xenobiotics.

Biodegradation, Environmental↗
PubMedDate not supplied

[Rapid method for determining cellobiase activity].

A simple and rapid method for determining the cellobiase activity in purified enzyme preparations was developed. It is based on a series of consecutive enzymatic reactions, i. e. hydrolysis of cellobiose by cellobiase, oxidation of the forming glucose by glucose oxidase, and formation of a dyed product under peroxidase action in the same reaction system. The dyed product is recorded spectrophotometrically at 460 nm. One measurement takes from 2-3 to 7-10 min depending on a particular method of the activity determining. The reagent which is used for the activity determining can be obtained in the yophylized form and used repeatedly. The relative deviation of the method is 5-7%.

Aspergillus↗