You are examining the effects of a mutation in the proximal histidine of a heme-containing protein. This mutation has changed the histidine into an alanine. Based on your knowledge of the role of heme in hemoglobin and how it is coordinated in the protein, what is the MOST likely effect of the mutation? A) Heme will no longer be bound in the protein. B) The iron in heme will be fully coordinated. C) The iron in heme will have two uncoordinated bonds. D) The heme will be able to bind to O₂ more effectively than it will to CO. E) There will be no effect on the protein due to this mutation.

Question

Quizplus · Accepted Answer

The proximal histidine is responsible for coordinating the iron in heme in a partially coordinated state, allowing for reversible oxygen binding. The mutation of histidine to alanine will disrupt this coordination, leading to two uncoordinated bonds and making it difficult for the heme to bind and release oxygen effectively. Therefore, the most likely effect of this mutation is that the iron in heme will have two uncoordinated bonds.

You Are Examining the Effects of a Mutation in the Proximal