Sandbox Reserved 640
From Proteopedia
Leghemoglobin
Introduction
|
Function
Structure
The 16 kDa 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). Depending on the species and specific type of Leghemoglobin, the primary amino acid sequence can differ some, but overall it is well conserved. The heme group, however, has been found to be largely the same in different proteins and in different species (Ref 1). The main difference is the heme group is considerably larger in Leghemoglobin than its other oxygen-transferring globin counterparts. This makes the oxygen affinity larger than that of Myoglobin and Hemoglobin (Ref 8).
This 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). 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***
The methods by which various
