BIO 361 Study Guide - Midterm Guide: Myosin Head, Monod-Wyman-Changeux Model, Disulfide
29 Jul 2016
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Document Summary
Burying oxygen in binding sites away from water onto the heme iron. The heme iron is ferrous, fe(ii) which oxidizes to ferric, fe(iii) upon binding of oxygen. When oxygen is bound, heme iron color is orangey. When oxygen is released, heme iron color is violet. Hemoglobin has a tetrapyrrole ( 2 2 tetramer) structure that allows for positive cooperativity (sigmoidal-shaped curve) 80% of proteins are -helices (there are 8 -helices) in both hemoglobin and myoglobin. In the absence of oxygen, the iron is linked to the protein via a pentacoordinate complex. In the presence of oxygen, the iron is linked to the protein via a hexacoordinate complex. There are side chains or the globin portion of each polypeptide composed of valine and phenylalanine (hydrophobic) side chains that disallows access of water to the heme iron. Allows for releasing of oxygen to tissues at around pressures of 20-40 mm hg (75% of oxygen content bound in lungs remains on hemoglobin)
