Question

10. Please identify two enzymes that catalyze substrate-level phosphorylation reactions, one in glycolysis and one in the tricarboxylic acid cycle. For each, identify the high-energy substrate that provides the energy to drive the phosphoryl transfer. 11. How are the pyruvate dehydrogenase complex and the a-ketoglutarate dehydrogenase complex similar and how are they different?

Answer 1

10. The formation of ATP by phosphoryl group transfer from a substrate is referred to as substrate-level phosphorylation.

For Glycolysis

The enzyme phosphoglycerate kinase catalyzes the transfer of high energy phosphoryl group from the carbon group of 1,3-Bisphosphoglycerate to ADP (Adenosine Diphosphate) and forms 3-Phosphoglycerate along with ATP (Adenosine Triphosphate).

The high energy substrate is 1,3-Bisphosphoglycerate in this case.

For Citric Acid Cycle

The enzyme Succinyl-CoA synthetase catalyzes the breakage of the thioester bond of Succinyl-CoA to drive the synthesis of a phosphoanhydride bond in either GTP (Guanosine Triphosphate) or ATP (Adenosine Triphosphate).

The high energy substrate is Succinyl-CoA in this case.

FOR GLYCOLYSIS STEP : PHOSPHORYL TRANSFER FROM 1,3- Bisphosphoglycerate TO ADP ENZYME : PHOSPHOGLYCER ATE KINASE SUBSTRATE: 1, 3- Bisphosphoglycerate V O -P-o- 2 ADP 2ATP 71 HCON HCOM Phosphoglycerate Kinase CH2 OPOR- 1,3-Bisphosphoglycerate CH2020,3- 3- Phosphoglycerate FOR CITRIC ACID CYCLE STEP : CONVERSION OF Succinyl-COA To Succinate ENZYME : Succinyl-CoA Synthetase SUBSTRATE : Succinyl-CoA CM2- COO- - GDP+ Pi GTP COA-SH Coo CH₂ CH2 ċ-SCOA Succinyl-CoA CH2 Synthetase Succinyl-CoA COO Succinate ABBREVIATIONS ATP - ADENOSINE TRIPHOSPHATE ADP - ADENOSINE DI PHOSPHATE COA - Coenzyme A CScanned with CamScanner