[Interaction of muscle glycogen phosphorylase b with riboflavin, its tetraacetyl derivative and their analogs].
The interaction of rabbit skeletal muscle glycogen phosphorylase b with riboflavin, 2',3',4',5'-tetraacetylriboflavin and their analogues, containing different substituents in the positions 6, 8 and 8 alpha, has been studied. Dissociation constant for the complex of the enzyme and riboflavin was determined to be 12.5 microM (pH 6.8; 20 degrees C) by sedimentation velocity method. Riboflavin and its analogues have been found to inhibit glycogen phosphorylase b. The inhibitor half-saturation concentration values increase in the following order: riboflavin (18 microM), 8-methoxy(nor)rifoblavin (23 microM), 8 alpha-bromo-2',3',4',5'-tetraacetylriboflavin (40 microM), 6-bromoriboflavin (40 microM), 8 alpha-hydroxyriboflavin (60 microM), 8-hydroxy(nor)riboflavin (90 microM), 8 alpha-(gamma-carboxypropylamino-2',3',4',5'-tetraacetylriboflav in (90 microM), 8 alpha-[p-(5-ethyl-1,3,4-thiodiazol-2-ylsulfamido)phenylamino ]- 2',3',4',5'-tetraacetylriboflavin (100 microM), 8 alpha-(L-methionyno)-2',3',4',5'-tetraacetylriboflavin (120 microM), 8 alpha-[p-(thiazol-2-ylsulfamido)phenylamino]- 2',3',4',5'-tetraacetylriboflavin (140 microM), 8 alpha-(p-sulfamidophenylamino)-2',3',4',5'-tetraacetylriboflavi n (180 microM), 8 alpha-(p-carboxyphenylamino)-2',3',4',5'-tetraacetylriboflavin+ ++ (210 microM), 2',3',4',5'-tetraacetylriboflavin (250 microM), 8 alpha-(L-homoserino)-2',3',4',5'-tetraacetylriboflavin (340 microM), 8 alpha-(L-glutamo)-2',3',4',5'-tetraacetylriboflavin (360 microM). The existence of glycogen phosphorylase b complexes with riboflavin and its analogues has been proved by methods of absolute and difference spectrophotometry.
Klinov
S V
SV
Kurganov
B I
BI
Chebotareva
N A
NA
Zhilina
T A
TA
Litvak
Zh I
ZhI
D000818:Animals; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D010763:Phosphorylase b / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D011817:Rabbits; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000378:metabolism; D013053:Spectrophotometry
C058357:2',3',4',5'-tetraacetylriboflavin; D010763:Phosphorylase b; D006005:Phosphorylases; D012256:Riboflavin
Vzaimodeĭstvie myshechnoĭ glikogenfosforilazy b s riboflavinom, ego tetraatsetilproizvodnym i ikhh analogami.