We are protected to some extent against low level CO poisoning because: A) His F8 on Hb distorts the heme iron atom out of the heme plane and attracts O₂, but not CO. B) Affinity of Hb for O₂ is much greater than for CO. C) His E7 blocks perpendicular binding of CO to heme iron allowing for better binding competition by O₂. D) The competition of O₂ for heme is much greater than CO for heme. E) None of the above.

Question

Quizplus · Accepted Answer

His E7 (histidine at the E7 position) in hemoglobin provides some protection against carbon monoxide (CO) poisoning by hindering the direct perpendicular approach of CO to the heme iron, which allows oxygen (O2) to compete more effectively for binding sites.

We Are Protected to Some Extent Against Low Level CO