ABSTRACT
The amino acid composition of glucosoisomerase from Actinomyces olivocinereus 154 was investigated. The content of dicarboxylic acids--aspartic and glutamic--was found to be greater than that of basic acids--lysine, arginine and histidine. Hydrophobic acids were also detected to occur on appreciable quantities. No cysteine was seen in the enzyme. The experimental data on the effect of sodium dodecyl sulfate and urea suggests that the enzyme has a quaternary structure consisting of four nonidentical subunits.
Subject(s)
Actinomyces/enzymology , Aldose-Ketose Isomerases , Carbohydrate Epimerases , Amino Acids/analysis , Carbohydrate Epimerases/metabolism , Cobalt/pharmacology , Kinetics , Macromolecular Substances , Magnesium/pharmacology , Protein ConformationABSTRACT
The inhibitory action of polyols, e. g. D-mannitol, D-glucitol, ribitol and xylitol, on the activity of glucose isomerase prepared from Actinomyces olivocinereus 154 was studied. All the polyols under study are purely reversible competitive inhibitors. The values of Ki for D-mannitol, D-sorbitol, D-arabitol, D-glucitol, ribitol and xylitol are 0.200, 0.140, 0.030, 0.024 and 0.020 M, respectively. The inhibition is to some extent decreased by increasing concentrations of the substrate and is completely abolished by increasing concentrations of Mg2+ and Co2+--up to 5.10(-2) and 5.10(-3) M, respectively.
Subject(s)
Actinomyces/enzymology , Aldose-Ketose Isomerases , Carbohydrate Epimerases/antagonists & inhibitors , Sugar Alcohols/pharmacology , Binding, Competitive , Cobalt/pharmacology , Kinetics , Magnesium/pharmacology , Structure-Activity RelationshipABSTRACT
Conversion of D-glucose into D-fructose in a column reactor of a continuous type was studied using an immobilized enzyme, glucose isomerase from Actinomyces olivocinereus. The effective parameters of Km, Vmax, energy activation at various flow rates were calculated. During 32 days of continuous operation the enzyme activity fell down to 84% of the initial level. A system of recirculation was employed to use immobilized glucose isomerase with a low activity.
Subject(s)
Actinomyces/enzymology , Aldose-Ketose Isomerases , Carbohydrate Epimerases/metabolism , Enzymes, Immobilized/metabolism , Enzyme Activation , Fructose , Glucose , Kinetics , TemperatureABSTRACT
The paper presents a method for producing highly purified glucosoisomerase from Actinomyces olivocinereus 154. The scheme of purification includes enzyme extraction from dry biomass, acetone fractionation, ammonium sulfate precicipation, and Sephadex G-200 chromatography. The highly purified enzyme is homogeneous as shown by polyacryl amide gel electrophoresis, analytical ultracentrifugation, and gel filtration. The highly purified enzyme has been prepared in a crystalline form. The molecular weight of the enzyme has been estimated by sedimentation equilibrium to be 162 000 and by gel filtration to be 158 000. The sedimentation constant of glucosoisomerase has been found to be 8.52 S.
Subject(s)
Actinomyces/enzymology , Aldose-Ketose Isomerases , Carbohydrate Epimerases/isolation & purification , Chromatography, Gel , Crystallization , Molecular WeightABSTRACT
Glucose-isomerizing enzyme was isolated from the culture of Actinomyces olivocinereus. It was purified by the chromatography on DEAE-cellulose. The samples of glucose-isomerasing enzyme are homogeneous according to the results of analytical electrophoresis and ultracentrifugation. Glucose-isomerase is more stable than soluble one. The pH-optima of soluble and immobilized enzymes are 8.5 and 7.5, respectively. The temperature optimum of immobilized enzyme, Km, V, and activation energy do not change during immobilization. The immobilized sample has 58% activity of soluble enzyme.
