This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: TCA Cycle, Subject name: Biochemistry
All of the following TCA cycle enzymes are located in the mitochondrial matrix, EXCEPT 
Select and explain. 
A. Alpha-ketoglutarate dehydrogenase, B. Isocitrate dehydrogenase, C. Succinate dehydrogenase, D. Malate dehydrogenase
C: Succinate dehydrogenase
Answer: C: Succinate dehydrogenase 
Explanation: Ans. c)Succinate dehydrogenase * All the TCA cycle enzymes are present in the mitochondrial matrix except succinate dehydrogenase (complex II of ETC) * Succinate dehydrogenase is embedded in the inner mitochondrial membrane. NOTE: Complex I pumps 4 protons. Complex II doesn't pump any proton. Complex III pumps 4 protons. Complex IV pumps 2 protons.