Candidate Dehydron Identification in High Resolution Myoglobin Structures

In this report we provide a detailed analysis of candidate dehydrons in high resolution myoglobin (Mb) structures and an additional high-resolution hemoglobin (Hb) monomer. The eighty-eight selected structures were first grouped according to a sequence classification rule, resulting in nineteen identical sequence groups (ISGs). Each ISG member structure was analyzed using the WRAPPA program to identify putative, or “candidate,” dehydrons. Global candidate dehydron distributions (GCDDs) were then identified for each structure, and both between-ISG and within-ISG GCDD variation was examined. Candidate dehydrons found in close proximity to heme and other bound groups were also examined, with a focus on (a) dehydrons with constituent atoms involved in polar interactions with the heme group, and (b) dehydrons found within the vicinity of one or more heme non-polar carbons. These latter dehydrons are denoted heme-wrapped candidate dehydrons (HWCDs). GCDDs and HWCDs conserved within individual ISGs and among different ISGs were identified. A single HWCD was found to be conserved among seventeen of the nineteen ISGs: the His97Ser92/analog candidate dehydron. In addition, a surprisingly high degree of variability was found for both withinand between-ISG GCDDs.