This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mechanisms of Enzyme Action, Subject name: Biochemistry
CO is released in reaction catalyzed by- 
Select and explain. 
A. Decarboxylases, B. Carboxylases, C. Heme oxygenase, D. Pyruvate dehydrogenase
C: Heme oxygenase
Answer: C: Heme oxygenase 
Explanation: Ans. is 'c' i.e., Heme oxygenase o The oxidation of heme, catalyzed by heme oxygenase, releases carbon monoxide, iron and biliverdin IX a.o Low levels of CO derived from heme oxygenase reaction in certain tissues play an important role in physiological response to stress.o CO participates in several signalling pathways in which CO exerts vasoregulatory, anti-inflammatory, antiapoptotic and antiproliferative effects.o Evidence is accumulating that CO plays an especially important role in neural signaling.