BIOC 3560 Lecture Notes - Lecture 3: Hemoglobin, Propionate, Heme
29 Sep 2016
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Heme is bound between e and f helices. Myoglobin: monomer binds and stores oxygen in muscle. Large marine mammals that do deep dives have a lot of myoglobin. Leghemoglobin: similar to hb, found in leguminous plants. Sequesters o2, protects o2-sensitive enzymes in n2-fixing bacteria. Heme- binding pocket: formed by e and f helices. Propionate side chains of heme are near the surface of the globin (this is not the case for all porphyrias) The rest of the heme is surrounded by non-polar residues (except for two histidines) His- bonding: proximal histidine (close to fe), is directly bonded to fe2+ at f8, distal histidine is close, but not bonded to heme. Respnsible for reducing affinity for co, and keeping fe2+ from being oxidized to. Fe3: o2 binds to fe2+ on e7 side of the atom. Myoglobin (mb: single polypeptide, 153 residues, binding of o2 depends on:
