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At least 145 records · Page 8Linked to original sources
PubMed1976

Resolution and complementation of the labile L-leucine-pyruvate transaminase. An intermediate during enzyme formation under nitrogen starvation in Gluconobacter suboxydans.

L-Leucine-pyruvate transaminase (mol. wt. 70 000) in Gluconobactersuboxydans synthesized during nitrogen starvation contained a labile form which changed to the stable one later. The labile enzyme (mol. wt. 70 000) dissocated to the two proteinaceous components: a cationic one (mol. wt. 10 000--20 000) and an anionic one (mol. wt. 50 000--60 000), during column chromatography on DEAE-cellulose. The enzyme activity was reconstructed when they were mixed. The reconstructed enzyme had almost the same molecular size and enzymatic properties as the labile and the native stable enzymes.

Drug Stability↗
PubMed1995

Cloning and Nucleotide Sequencing of the Membrane-Bound l-Sorbosone Dehydrogenase Gene of Acetobacter liquefaciens IFO 12258 and Its Expression in Gluconobacter oxydans.

Volume 61, no. 2, p. 419, column 1, lines 15-19: this sentence should read as follows. "The alcohol dehydrogenase and glucose dehydrogenase have a common region reported to be related to pyrroloquinoline quinone binding (2, 10), but SNDH does not contain such a region, indicating that SNDH is not a quinoprotein." Page 419, column 2, line 12: "(Table 4)" should read "(Table 3)." [This corrects the article on p. 413 in vol. 61.].

Journal Article↗
PubMed2002

Productivity improvement in l-sorbose biosynthesis by fedbatch cultivation of Gluconobacter oxydans.

The effect of increased (100, 200 and 300 gl(-1)) initial sorbitol concentrations (S0) was investigated in the sorbitol to sorbose bioconversion process. Batch cultivations with a S0 of 100, 200 and 300 gl(-1) were completed at 10, 14 and 24 h with a corresponding overall sorbose productivity of 10.1, 14.3 and 12.4 gl(-1) h(-1) respectively. The decrease in sorbose productivity at S0=300 gl(-1) was attributed to the inhibition by sorbitol of culture growth and product formation. In order to eliminate substrate inhibition, two identical fed-batch cultivations were performed in which a highly concentrated (500 gl(-1)) sorbitol solution was added at a constant feed rate (0.2 l h(-1)) in the exponential phase of growth. The Fed-batch culture initiated with S0=225 gl(-1) exhibited an enhanced accumulation of sorbose (336.2 gl(-1)) but with a processing time of 24 h, and a productivity of 14.0 gl(-1) h(-1). While, the fed-batch culture initiated with S0=100 gl(-1) accumulated 279.7 gl(-1) of sorbose with an increase in productivity of 17.6 gl(-1) h(-1) in 16 h.

Journal Article↗
PubMed1978

[Coenzyme-induced slow transitions of NADP-sorbitol dehydrogenase from Gluconobacter oxydans].

The kinetic properties of NADP-dependent sorbitol dehydrogenase from G. oxydans cell extract were studied at pH 8.8 and 9.3 in the direction of D-sorbitol oxydation. It was shown that the shape of the kinetic curves of NADPH accumulation in time is characterised by initial burst whose magnitude depends on the concentration of the enzyme extract used. Preincubation of the enzyme with NADP or D-sorbitol eliminated the initial burst on these curves and transformed them into straight lines coming from the start of co-ordinates. The dependence of the stationary reaction rate on the enzyme extract concentration is not a linear one. The kinetic dependences of stationary rate of the reaction catalysed by the enzyme on the concentration of D-sorbitol and NADP at pH 8.8 and 9.3 were examined under all conditions studied; the shape of these kinetic curves altered to considerable extent with the alteration of the enzyme extract concentration in the reaction mixture and pH. At pH 9.3 several intermiediate plateaux were found on the curves of the D-sorbitol concentration dependent stationary rate of the reaction. The preincubation of the enzyme extract with NADP during 1.5 h removed the intermediate plateau on these curves and made them hyperbolic. Disk-electrophoresis of the enzyme extract in PAAG concentration gradient showed that at pH 8.8 the enzyme exists in one active form, while at pH 9.3 it exists in three major and three minor active forms of the enzyme differing in their molecular weights are found. It is assumed that the enzyme from G. oxydans cell extract can exist in a great number of molecular equilibrium forms, the rate of quilibrium being comparable or significantly less than that of the enzymatic reaction. NADP significantly influences on the equilibrium of the molecular forms of the enzyme.

Hydrogen-Ion Concentration↗
PubMed1980

[Purification and properties of levansucrase of Gluconobacter oxydans L-1].

Levansucrase of G. oxydans L-1 which catalyzes the synthesis of the polysaccharide levan from the fructofuranosyl residues of sucrose has been isolated from the culture fluid and purified by chromatography on hydroxyapatite and gel-filtration on Sephadex G-100. The molecular weight of levansucrase as measured by DS-Na polyacrylamide gel electrophoresis is about 58000. The enzyme contains 25.86% of acidic amino acids, 13.74% of basic amino acids and 12.77% of aromatic amino acids. No cystine or cysteine residues were detected in the acid hydrolysate. The UV-absorption spectrum of the purified protein has a maximum at 280 nm and a minimum at 254 nm. The kinetic data suggest that levansucrase catalyzes levan formation, sucrose hydrolysis and sucrose glycosyl-free glucose exchange reactions. The initial rates of liberation of labelled glucose and labelled fructose during transfructosylation have been determined. Low molecular weight levans accelerate the rate of the polysaccharide formation and increase the ratio of the formed levan to free fructose.

Amino Acids↗