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At least 19 recordsLinked to original sources
PubMed1977

[Analgos of riboflavin, lumiflavin and alloxazine derivatives. II. Effect of roseoflavin on 6,7-dimethyl-8-ribityllumazine and riboflavin synthetase synthesis and growth of Bacillus subtilis].

The replacement of 8-CH3 group in the riboflavin molecule results in the formation of specific antimetabolites. They are rozeoflavin, 7-desmethylrozeoflavin, 8-amino (nor) riboflavin, 8-ribitylamino (nor) riboflavin. Effect of rozeoflavin and other riboflavin analogues on the growth and regulatory characteristics of Bacillus subtilis strains with different genetic state of riboflavin operon is studied. Roseoflavin at a concentration of 0.05 mkg/ml inhibits DRL synthesis in rib-b110 strain. An analogue inhibits the growth of auxotrophic and prototrophic strains at concentrations of 0.5 mkg/ml and 50 mkg/ml respectively. Riboflavin (1 mkg/ml) recovers the growth of bacteria. The curve of rozeoflavin regulation of DRL and riboflavin synthetase synthesis is shifted in 100 times in the direction of lesser concentrations as compared with riboflavin and 8 amino (nor) riboflavin. 180 mutants resistant to 100 mkg/ml of rozeoflavin were selected. 150 mutants over-synthetize riboflavin.

Bacillus subtilis↗
PubMed1975

[Riboflavin and lumiflavin analogs and alloxazine derivatives. I. Effect on riboflavin synthesis by and growth of Bacillus subtilis].

Effect of riboflavin, lumiflavin and a number of alloxazine derivatives is studied on the growth of three Bacillus subtilis strains with different genetic state of riboflavin operon as well as their ability to show coenzyme and regulating properties characteristic of vitamin B2. The fission of the ribityl chain of the riboflavin molecule results in the complete loss of both coenzyme and regulating properties of vitamin B2 (analogues of lumiflavin and alloxazine derivatives). Different types of esterification of hydroxyl groups of ribityl chain or its replacement by dulcityl chain results in the decrease of regulating properties characteristic of riboflavin as an end product of biosynthetic pathway (tetraacetylriboflavin and its derivatives, tetrapropionyl- and tetrabutyrylriboflavin) or to the loss of coenzyme and regulating activities (galactoflavin and tetrabenzoylriboflavin). The length increase of hydrocarbon chain under esterification of hydroxyl groups in ribityl chain results in enhancing vitamin B2 non-specific inhibitory effect on the growth of Bacillus subtilis strains studied. The replacement of 8-CH3 group in the riboflavin molecule by amino- or D-ribitylaminogroup results in the formation of specific antimetabolites, 8-amino(nor)riboflavin and 8-D-ribitylamino(nor)riboflavin respectively. Depending on the nature of other alterations or replacements of the 8-CH3 group of riboflavin molecule and their combinations with alterations of ribityl chain the reduction of the regulating activity (8-alpha-bromtetraacetylriboflavin) or a sharp decrease of coenzyme and regulating functions (analogues N 9 to N 15) takes place. The replacement of riboflavin-5-N-oxide and 2-thioriboflavin type did not affect the studied properties of riboflavin.

Bacillus subtilis↗
PubMed1977

Utilization of analogues of riboflavin by the riboflavin-deficient chick embryo.

Detailed studies of the biological activity of several analogues of riboflavin in the riboflavin-deficient chick embryo were undertaken to extend our knowledge of the comparative biochemistry of these flavins. The riboflavin-deficient eggs were produced by hens homozygous for an autosomal recessive gene (rdrd). 7-Ethyl-8-methyl-flavin was found to be an adequate replacement for riboflavin in che chick embryo, a finding which mimics its effect in the riboflavin-deficient rat. 7,8-Diethyl-flavin was found to be an antagonist in the chick embryo as had been found to be true in the rat. 7-Methyl-8-ethyl-flavin can not be used as a replacement for riboflavin in the chick embryo and further, it inhibits the utilization of riboflavin in normal eggs. 7-Methyl-8-ethyl-flavin had been found to be an adequate replacement for riboflavin in the riboflavin-deficient rat. The classes mammalia and aves are clearly different in respect to the utilization of this flavin.

Animals↗
PubMed1978

Biosynthesis of riboflavin in Bacillus subtilis: function and genetic control of the riboflavin synthase complex.

Two riboflavin synthase activities (heavy and light) have been observed in earlier studies with Bacillus subtilis. The heavy enzyme is a complex of one molecule of light enzyme (consisting of three alpha subunits) and approximately 60 beta subunits (A. Bacher, R. Bauer, U. Eggers, H. Harders, and H. Schnepple, p. 729--732, in T. P. Singer (ed.), Flavins and Flavoproteins, Elsevier, Amsterdam, 1976). The formation of alpha and beta subunits is coordinately controlled. Mutants apparently deficient in beta subunits were isolated as riboflavin requires after mutagenesis of B. subtilis with ICR 191. The mutants could grow with diacetyl instead of riboflavin. Growth with diacetyl was associated with the accumulation of substantial amounts of the riboflavin precursor, 6,7-dimethyl-8-(D-ribityl)lumazine. It follows that the mutants are deficient in an enzyme activity required for the formation of the lumazine from the pyrimidine precursor. We conclude that heavy riboflavin synthase is a bifunctional enzyme. The riboflavin synthase activity is mediated by the alpha subunits, whereas the beta subunits are necessary for an earlier biosynthetic step.

Bacillus subtilis↗
PubMed1978

Aldosterone stimulation of riboflavin incorporation into rat renal flavin coenzymes and the effect of inhibition by riboflavin analogues on sodium reabsorption.

This study was designed to investigate a possible relationship between the effect of aldosterone upon urinary electrolytes and the incorporation of [(14)C]riboflavin into renal [(14)C]flavin mononucleotide (FMN) and [(14)C]flavin adenine dinucleotide (FAD). Adrenalectomized Sprague-Dawley rats that weighed between 185 and 210 g were pretreated with 15 mug/100 g body wt dexamethasone intraperitoneally. 16 h later they were administered aldosterone (1.5 mug/100 g body wt) and [(14)C]riboflavin (5.0 muCi/200 g body wt). The urethra of each rat was ligated, and the rats were sacrificed by decapitation 3 h later. The urine was aspirated from the bladders of each rat and analyzed for total Na(+) and K(+) excretion while the kidneys were removed and the formation of [(14)C]FMN and [(14)C]FAD was determined for each kidney. There was a significant increase in the formation of renal [(14)C]FMN and [(14)C]FAD (27.3 and 14.4%, respectively) after aldosterone treatment. Aldosterone significantly decreased the excretion of Na(+) by 50%, and increased that of K(+) by 55%. To determine if the increased incorporation of [(14)C]riboflavin into renal [(14)C]FMN and [(14)C]FAD was an important intermediary step in the aldosterone-induced alterations in urinary Na(+) and K(+), the riboflavin analogues 7,8-dimethyl-10-formylmethyl isoalloxazine or 7,8-dimethyl-10-(2'-hydroxyethyl) isoalloxazine were given to the animals i.p. to diminish the conversion of riboflavin to FMN by competitively inhibiting the enzyme flavokinase (EC 2.7.1.26). These analogues were found to significantly counteract the decreased urinary excretion of Na(+) as a result of aldosterone from 26+/-9% to 124+/-58% (SEM) with a dose-related response when administered from 10 to 25 mug/100 g body wt. The same doses of the analogues that significantly increased the urinary output of Na(+) when administered simultaneously with aldosterone also significantly decreased the formation of renal [(14)C]FMN from 15+/-4 to 38+/-3% when compared with the effects of aldosterone alone. The analogues exerted no significant effect on the increased urinary excretion of K(+) by aldosterone. The analogues alone had no influence on urinary Na(+) and K(+) output or the formation of renal [(14)C]FMN and [(14)C]FAD at the dose levels that we investigated. These data strongly suggest that the enhanced synthesis of renal FMN and FAD may be a causative factor in the increased reabsorption of Na(+) as a result of aldosterone; and, consequently, riboflavin analogues may function as a novel class of antimineralocorticoids.

Aldosterone↗
PubMed1978

[Operon of riboflavin biosynthesis in Bacillus subtilis. XV. A study of mutants related to the initial stages of biosynthesis. The origin of the ribityl chain of the riboflavin molecule].

The incorporation of 14C-labelled guanosine and xanthosine into riboflavin was studied. It is concluded that the ribose mojety of guanosine is converted to the ribityl side chain of riboflavin. Thus the immediate precursor of riboflavin biosynthesis is a guanosine compound. Two classes of the riboflavin-dependent mutants of Bacillus subtilis were studied. They are closely linked to the lysine markers and probably correspond to the initial steps of riboflavin biosynthesis pathway.

Bacillus subtilis↗
PubMedDate not supplied

[Riboflavin transport in cells of riboflavin-dependent yeast mutants].

Riboflavin was transported at a high rate into yeast cells of Pichia guilliermondii and Schwanniomyces occidentalis mutants capable of growth in a medium containing low concentrations of riboflavin, and having multiple susceptibility to some antibiotics and antimetabolites. Sucrose and sodium azide inhibited transport of riboflavin. Other riboflavin dependent mutants of Pichia guilliermondii, Pichia ohmeri, Torulopsis candida, and Saccharomyces cerevisiae, also growing in media containing low concentrations of riboflavin, were not capable of its active transport.

Biological Transport, Active↗
PubMed1979

Purification of riboflavin-binding proteins from bovine plasma and discovery of a pregnancy-specific riboflavin-binding protein.

Riboflavin-binding proteins have been purified from bovine plasma using flavinyl agarose beads. At least three major protein bands, migrating in regions assigned to the beta- and gamma-globulins of plasma, are observed by cellulose acetate electrophoresis. These proteins coelute from a calibrated Sephadex G-100 column in the volume corresponding to a molecular weight of approximately 150,000; a small amount of another riboflavin-binding protein (molecular weight approximately 37,000) is also present. Polyacrylamide gel electrophoresis of the proteins, with detection by autoradiography of those having tightly bound [2-14C]riboflavin, reveals one protein band which is present only in preparations from pregnant cows. This protein has been purified to apparent homogeneity by storing the mixture of riboflavin-binding proteins at 8 degrees C for 3 weeks, which precipitates the other, less stable proteins. Hence, bovine plasma, like that of the laying hen, contains a number of riboflavin-binding proteins, one of which correlates with pregnancy.

Animals↗
PubMed1976

Regulation of 6-hydroxy-2,4,5-triaminopyrimidine synthesis by riboflavin and iron in riboflavin-deficient mutants of Pichia guilliermondii yeast.

The effect of riboflavin and iron on 6-hydroxy-2,4,5-triaminopyrimidine synthesis rate was investigated in the cultures of the yeast Pichia guilliermondii (rib2 mutants) with the blocked second reaction to flavinogenesis. It was shown that riboflavin inhibited the 6-hydroxy-2,4,5-triaminopyrimidine synthesis rate in iron-rich and iron-deficient cells of mutants with low riboflavin requirements. Cycloheximide did not prevent the stimulation of 6-hydroxy-2,4,5-triaminopyrimidine synthesis caused by riboflavin starvation. 7-methyl-8-trifluoromethyl-10-(1'-D-ribityl)isoalloxazine strongly inhibited the 6-hydroxy-2,4,5-triaminopyrimidine synthesis, while 7-methyl-8-trifluoro-methyl-10-(beta-hydroxyethyl)izoalloxazine and galactoflavin exerted only a slight effect on this process. The 6-hydroxy-2,4,5-triaminopyrimidine synthesis rate in iron-deficient cells was significantly higher than in iron-rich cells. The 2,2'-dipyridyl treatment of iron-rich cells caused the stimulation of 6-hydroxy-2,4,5-triaminopyrimidine synthesis and cycloheximide abolished this effect. The results suggest that the activity of the first enzyme of flavinogenesis (guanylic cyclohydrolase) is under the control of feedback inhibition by flavins and the biosynthesis of this enzyme is regulated by iron.

2,2'-Dipyridyl↗
PubMed1978

Resonance Raman spectra of riboflavin and its derivatives in the bound state with egg riboflavin binding proteins.

The resonance Raman spectra of riboflavin (RF) and its derivatives, including 3-deuterated (3-D RF), 3-methyl (3-CH3 RF), 3-carboxymethyl (3-CH2COOH RF), and 7,8-dichlororiboflavins (7,8-Cl RF), in H2O and D2O were observed in the 700-1700 cm-1 region. The fluorescence problem of riboflavin was overcome by complex formation of riboflavin with riboflavin binding proteins. The observed frequencies of Raman lines of RF are in good agreement with those of glucose oxidase obtained by Spiro et al. by the resonance CARS method, although the present spectral range is extended to much lower frequency with a higher signal-to-noise ratio than that for glucose oxidase. The observed Raman lines were assigned to the individual ring modes of isoalloxazine on the basis of the Raman spectra of appropriate model compounds such as uracil, pyrazine, and o-xylene. The 1253 cm-1 line of RF was shifted to ca. 1300 cm-1 for 3-D RF, 3-CH3 RF, and 3-CH2COOH RF, and accordingly can be assigned to the CN stretching mode of Ring III. The 1632 cm-1 line of RF was shifted for 7,8-Cl RF and was assigned to a Ring I mode. No Raman line mainly due to C = O stretching mode was observed in the present resonance Raman spectra.

Carrier Proteins↗
PubMed1978

Biosynthesis of riboflavin. 6,7-Dimethyl-8-ribityllumazine 5'-phosphate is not a substrate for riboflavin synthase.

Phosphotransferase from carrot is shown to catalyze the phosphorylation of 6,7-dimethyl-8-ribityllumazine specifically at position 5' of the ribityl side chain. The lumazine 5'-phosphate is neither a substrate nor an inhibitor of riboflavin synthase from Bacillus subtilis and Escherichia coli. It follows that the obligatory product of riboflavin synthase is riboflavin and not FMN.

Bacillus subtilis↗
PubMed1979

Anti-riboflavin activity of 8-O-alkyl derivatives of riboflavin in some Gram-positive bacteria.

Two new 8-O-alkyl derivatives of riboflavin (RF), i.e., 8-methoxy- (MOF), and 8-ethoxy-8-demethyl-D-riboflavin (EOF), their tetraacetate, and the tetraacetate of 8-hydroxy-8-demethyl-D-riboflavin (HOF) were synthesized. The anti-RF activity of MOF, EOF and HOF was estimated from the ratio CR/CI, where CI is the concentration of test flavin added to the culture medium and CR is the minimum concentration of RF needed to restore the growth inhibition. Their activity was also compared with that of roseoflavin (RoF). The decreasing order of anti-RF activity was as follows: MOF greater than RoF greater than EOF in Sarcina lutea: RoF greater than MOF greater than EOF in Bacillus cereus and Staphylococcus aureus. HOF showed no activity in any of the bacteria tested. The redox potential of these compounds decreases as follows: RF greater than RoF greater than EOF greater than MOF greater than HOF, and the RF activity of MOF and EOF could be explained by the redox potential difference between these compounds and RF.

Bacillus cereus↗
PubMed1978

[On the physiology of growth and riboflavin overproduction of Eremothecium ashbyii. III. Investigations on the incorporation of radioactive labeled substrates in cell material and riboflavin (author's transl)].

The incorporation of glycine-2-14C and adenine-U-14C in cell material and riboflavin was investigated in order to determine the proportions metabolites were channeled in growth processes and product synthesis of Eremothecium ashbyii. Extraction- and measurement methods were developed to compare the incorporation of radioactive metabolites into different cell fractions. Young cells incorporate the labeled compounds in a high rate into the cell material. With increasing age of the culture the incorporation of radioactivity is more directed to riboflavin. 96 hours old cells incorporate about seven times more 14C-adenine into riboflavin than into the cell material.

Adenine↗
PubMed1977

[Operon study of riboflavin biosynthesis in Bacillus subtilis. XII. The determination of the ATP:riboflavin-5'-phosphotransferase and riboflavinsynthetase content in the cells with varying genotypes].

Activities of riboflavinkinase and riboflavinsynthetase were measured in 15 strains of Bacillus subtilis with different genotype. The increased level of riboflavinkinase was observed in strains, resistant to lumiflavin or lumichrome. Specific activity of riboflavinkinase was found to be about 100 times lower than that of riboflavinsynthetase. The regulation of biosynthesis of these enzymes seems to proceed non-coordinately. This phenomenon can be the sequence of the existence of many operators, controlling the flavinogenesis in Bac. subtilis.

Bacillus subtilis↗