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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kinetic studies have demonstrated that vitamin B2 and its coenzyme forms FMN and FAD are potent inhibitors of glycogen phosphorylase b from rabbit skeletal muscle. The inhibition of the enzyme by flavins has a co-operative character (Hill coefficients exceed unity). Glycogen phosphorylase b bound to FMN or FAD does not reveal catalytic activity, whereas the enzyme bound to riboflavin retains about 16% of the initial catalytic activity.
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PMID:Inhibition of muscle glycogen phosphorylase b by vitamin B2 and its coenzyme forms. 309 25

Binding of vitamin B2 and its coenzyme forms by glycogen phosphorylase b was studied by sedimentation velocity and sedimentation equilibrium methods. Microscopic dissociation constants for complexes of the enzyme with riboflavin, FMN and FAD were found to be 12.5, 6.8 and 18.1 microM, respectively (0.1 M KCl, pH 6.8, 20 degrees C). We revealed also that glucose 1-phosphate, glycogen and AMP decreased the affinity of the enzyme for FMN.
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PMID:Binding of vitamin B2 and its coenzyme forms by muscle glycogen phosphorylase b. 309 26

The vitamin B2 and its coenzyme forms binding to glycogen phosphorylase b from rabbit skeletal muscle has been studied by the spectrophotometric method. The spectral properties of riboflavin, FMN and FAD bound to muscle glycogen phosphorylase b were found to be identical at the wavelengths of 300 to 500 nm. According to data on spectrophotometric titration of muscle glycogen phosphorylase b by FMN, each subunit of the enzyme contains one flavin-binding site.
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PMID:A spectrophotometric study of vitamin B2 and its coenzyme forms binding to muscle glycogen phosphorylase b. 309 32

The inhibition of rabbit skeletal muscle glycogen phosphorylase b by FAD and its analogues with substitutes in the position 8 has been studied. The value of half-saturation, [I]0,5, for inhibitors increases in the following order: FAD (44 microM), 8 alpha-hydroxy-FAD (60 microM), 8-dimethylamino (nor)-FAD (69 microM), 8 alpha-(N-acetyl-L-cystein-S-yl)-FAD (106 microM). From the comparison of these values with those obtained earlier for FMN analogues, it follows that in the case of FAD the half-saturation value is less sensitive to modification of the position 8 in the flavin isoalloxazine ring. The existence of the glycogen phosphorylase b FAD-complex has been proved by the spectrophotometry and sedimentation methods. The positions of maxima of optical absorption of the enzyme-bound FAD in the 300-500 nm region are identical with corresponding positions for FMN. FAD has been shown to hinder the AMP-induced transition of dimeric form of the enzyme to tetrameric one.
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PMID:[Interaction of muscle glycogen phosphorylase B with flavin-adenine dinucleotide and its analogs]. 392 80

The inhibition of glycogen phosphorylase b from rabbit skeletal muscles by the derivatives of riboflavin, FMN, FAD, and 2', 3', 4', 5'-tetraacetylriboflavin substituted in positions 6 and 8 of the isoalloxazine part of the flavin molecule is found to be cooperative (the Hill coefficient, h, exceeds 1.0). The modification of the flavin molecule slightly changes the value of the Hill coefficient, but results in the increase of the "half-saturation" concentration [I]0.5.
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PMID:Specificity of inhibition of muscle glycogen phosphorylase b by flavins. 777 99

The effect of three osmolytes, trimethylamine N-oxide (TMAO), betaine and proline, on the interaction of muscle glycogen phosphorylase b with allosteric inhibitor FAD has been examined. In the absence of osmolyte, the interaction is described by a single intrinsic dissociation constant (17.8 microM) for two equivalent and independent binding sites on the dimeric enzyme. However, the addition of osmolytes gives rise to sigmoidal dependencies of fractional enzyme-site saturation upon free inhibitor concentration. The source of this cooperativity has been shown by difference sedimentation velocity to be an osmolyte-mediated isomerization of phosphorylase b to a smaller dimeric state with decreased affinity for FAD. These results thus have substantiated a previous inference that the tendency for osmolyte-enhanced self-association of dimeric glycogen phosphorylase b in the presence of AMP was being countered by the corresponding effect of molecular crowding on an isomerization of dimer to a smaller, nonassociating state.
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PMID:Effect of osmolytes on the interaction of flavin adenine dinucleotide with muscle glycogen phosphorylase b. 1561 11