This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kerbs Cycle, Subject name: Biochemistry
Substrate level phosphorylation in citric acid cycle is catalysed by - 
Select and explain. 
A. Pyruvate kinase, B. Phosphogly cerate kinase, C. Malate dehydrogenase, D. Succinate thiokinase
D: Succinate thiokinase
Answer: D: Succinate thiokinase 
Explanation: Ans. is 'd' i.e., Succinate thiokinase o There are 2 types of phosphorylation of ADP to ATP.Substrate level phosphorylationOxidative phosphorylation at respiratory' chain levelo Substrate level phosphorylation is the production of ATP at the substrate level without participation of ETC.o It occurs in TCA cycle and glycolysis CitricAcid cydeSuccinate thiokinaseSuccinyi Co-A ---------------------------------------------------------- SuccinatePhosphnplyoerate kinaseGlycolys1. 1,3-Biphosphoglycerate ------------------------------------------------ 3-Phosphogly ceratePyruvate kinase2. Phosphoenolpvruvate ----------------------------------------------Pyruvate