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From Proteopedia
Leghemoglobin
Introduction
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Function
Structure
The polypeptide leghemoglobin consists of two main subunits, the main globin structure and the iron-encompassing heme (protoporphyrin XI) group. These two subunits form a molecule structurally similar to Myoglobin (Ref 1). The globin fold portion of the molecule is the standard globin secondary structure, a series of 8 alpha helices (Ref 5). The heme prosthetic group consists of four 5-membered pyrrole rings, forming a cyclic ring around a central iron (Fe) atam. This iron atom is contained within four equatorial nitrogens, in addition to another nitrogen from a close histidine residue and an opposite dioxygen (Ref 9). The leghemoglobin's heme group is considerably larger than other globin proteins, including hemoglobin and myoglobin, making its oxygen affinity larger (Ref 8). More specifically, the ligand contact residues are Phe30, His63, and Val67 (Ref 7). ***Add a section about H-bonding of the ligand with the Lb and how the heme group fits into the molecule***
