Glycolysis Regulation

2005 ◽  
Author(s):  
Gary D Lopaschuk ◽  
Jason RB Dyck
Keyword(s):  
Glycolysis Regulation

Phosphorylation is switch of L-type pyruvate kinase allostery

2010 ◽  
Vol 5 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Ilona Faustova ◽  
Aleksei Kuznetsov ◽  
Erkki Juronen ◽  
Mart Loog ◽  
Jaak Järv
Keyword(s):  
Pyruvate Kinase ◽  
Hill Coefficient ◽  
Stoichiometric Ratio ◽  
Allosteric Enzyme ◽  
E Coli ◽  
Glycolysis Regulation ◽  
Regulatory Phosphorylation ◽  
Pyruvate Kinase Isoenzymes ◽  
Dependent Protein ◽  
The Hill

AbstractAmong four pyruvate kinase isoenzymes, M1, M2, R and L, only M1 is considered as a nonallosteric enzyme. However, here we show that the non-phosphorylated L-type pyruvate kinase (L-PK) is also a non-allosteric enzyme with respect to its substrate phosphoenolpyruvate (PEP). The allosteric catalytic properties of L-PK are switched on through phosphorylation by cAMP-dependent protein kinase. The non-phosphorylated enzyme was produced by expressing the rat L-PK in E. coli, as the bacterium does not have mammalian-type protein kinases. The resulting tetrameric protein was phosphorylated with a stoichiometric ratio of one mole of phosphate per one L-PK monomer. Activity of the phosphorylated enzyme was allosterically regulated by PEP with the Hill coefficient n=2.5. It was observed that allostery was engaged by phosphorylation of the first subunit in the tetrameric enzyme, while further phosphorylation only modulated this effect. The discovered switching between non-allosteric and allosteric forms of L-PK and the possibility of modulating the allostery by phosphorylation are important for understanding of the interrelationship between allostery and the regulatory phosphorylation in general, and may have implication for further analysis of glycolysis regulation in the liver.

Controlling the highest lactate dehydrogenase activity known in nature

1978 ◽  
Vol 234 (3) ◽  
pp. R136-R140 ◽  
Author(s):  
M. Guppy ◽  
P. W. Hochachka
Keyword(s):  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
White Muscle ◽  
Aerobic Glycolysis ◽  
Anaerobic Capacity ◽  
Creatine Phosphate ◽  
Quiescent State ◽  
Lactate Dehydrogenase Activity ◽  
Glycerophosphate Dehydrogenase ◽  
Glycolysis Regulation

In the shipjack, Euthynnus pelamis, white muscle appears to possess a powerful anaerobic capacity as well as a significant carbohydrate based aerobic potential. Lactate dehydrogenase occurs at higher activities than found thus far anywhere else in nature and clearly functions in anaerobic glycolysis. Alpha-glycerophosphate dehydrogenase also occurs in unusually high activities and appears to play a role in aerobic glycolysis. Regulation of these two reactions is accomplished by temperature, pH, and creatine phosphate levels. High temperature, low pH, and low creatine phosphate levels all appear to favor lactate dehydrogenase over alpha-glycerophosphate dehydrogenase; low temperature, high pH, and high creatine-phosphate levels, all expected during the quiescent state in this species, and when metabolism in aerobic, all favor alpha-glycerophosphate dehydrogenase activity.

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