Which of the following enzyme does not catalyse reversible step in glycolysis?
Correct Answer: PFK
Description: Enzymes of glycolysis - a process which converts 6 carbon glucose to 3 carbon unit pyruvate & lactate - are present in cytoplasm. Whereas, complete oxidation of glucose (to CO2 & H2O) requires mitochondrial enzymes (of TCA cycle).
Out of total 9 enzymes used in glycolysis,
3 enzymes - hexokinase, phosphofructokinase (PFK-1) and pyruvate kinase are used in irreversible steps.
6 enzymes - phosphohexose isomerase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, 1, 3-bisphosphoglycerate kinase, phosphoglyceromutase and enolase are used in reversible steps.
2 enzymes used in energy utilizing steps are - hexokinase (using 1 ATP) and phosphofructokinase / PFK-1 (using 1 ATP). This energy consumption is for 1 molecule of glucose.
3 enzymes used in energy producing steps are - glyceraldehyde-3-phosphate dehydrogenase (producing 2 NADH = 5 ATP), 1, 3-bisphosphoglycerate kinase (producing 2 ATP) and pyruvate kinase (producing 2 ATP). This energy production is for 1 molecule of glucose or 2 molecules of glyceraldehyde-3-phosphate.
Category:
Biochemistry
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