[The effect of specific deimination of glycogen phosphorylase b by peptidylarginine deiminase on the allosteric properties of the enzyme and dimer-tetramer transition].
The kinetics of the native glycogen phosphorylase b from rabbit skeletal muscle and of the enzyme specifically deiminated by peptidylarginine deiminase have been studied. According to the data on amino acid composition one arginine residue per phosphorylase b monomer is transformed into citrulline after 3 hours of incubation with peptidylarginine deiminase. The kinetics of the phosphorylase reaction were studied in the direction of glycogen synthesis. The native and the deiminated forms of phosphorylase b showed similar affinity to glucose 1-phosphate. The maximal velocity of the enzymatic reaction for the modified phosphorylase b is 8-20% higher than that for the native enzyme. Deiminated phosphorylase b like the native enzyme shows a positive kinetic cooperatively with respect to glucose 1-phosphate in the presence of the allosteric inhibitors (FMN, glucose), S-shaped dependences of the velocity of the enzymatic reaction on glucose 1-phosphate concentration (in the presence of FMN) pronouncing more distinctly for deiminated phosphorylase b than for the native enzyme (Hill coefficient is equal to 1.7 +/- 0.2 and 1.3 +/- 0.1, respectively). The affinity of the modified phosphorylase b to the allosteric activator AMP is one order of magnitude higher than that to the native enzyme. The cooperativity of AMP binding doesn't change significantly after deimination. The kinetics of inhibition of the native and modified phosphorylase b by FMN, glucose and glucose 6-phosphate are cooperative (the value of Hill coefficient is higher than unity). The more pronounced distinctions between two forms of the enzyme concern with the value of the "semisaturation" concentration [I]0.5. The deimination causes a pronounced reduction of the values of [I]0.5 for FMN and glucose, but the sensitivity of the deiminated enzyme to glucose 6-phosphate is much lower than that of the native phosphorylase b. Deiminated phosphorylase b unlike the native enzyme shows the positive cooperativity of the FMN binding (the value of the Hill coefficient is equal to 1.37 +/- 0.05). Deiminated phosphorylase b shows less capability to form tetramer in the presence of AMP as compared to the native enzyme.
Eronina
T B
TB
Livanova
N B
NB
Chebotareva
N A
NA
Kurganov
B I
BI
Luo
S
S
Graves
D J
DJ
D000494:Allosteric Regulation; D000818:Animals; D001704:Biopolymers / Q000737:chemistry; D006867:Hydrolases / Q000737:chemistry* / Q000378:metabolism; D007097:Imines / Q000737:chemistry*; D007700:Kinetics; D018482:Muscle, Skeletal / Q000201:enzymology; D010763:Phosphorylase b / Q000037:antagonists & inhibitors / Q000737:chemistry*; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases; D011817:Rabbits
D001704:Biopolymers; D007097:Imines; D010763:Phosphorylase b; D006867:Hydrolases; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases
Vliianie spetsificheskogo deziminirovanniia glikogenfosforilazy b peptidilarginindeziminazoĭ na allostericheskie svoĭstva fermenta i dimer-tetramernye perekhody.