1G0B

CARBONMONOXY LIGANDED EQUINE HEMOGLOBIN PH 8.5

Summary for 1G0B

• Entry DOI: 10.2210/pdb1g0b/pdb
• Related: 1G08 1G09 1G0A
• Descriptor: HEMOGLOBIN ALPHA CHAIN, HEMOGLOBIN BETA CHAIN, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• Functional Keywords: equine, hemoglobin, liganded, carbonmonoxy, protoporphyrin ix, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Equus caballus (horse); More
• Total number of polymer chains: 2
• Total formula weight: 32459.55

Authors

Mueser, T.C.,Rogers, P.H.,Arnone, A. (deposition date: 2000-10-05, release date: 2000-12-27, Last modification date: 2024-02-07)

Primary citation

Mueser, T.C.,Rogers, P.H.,Arnone, A.
Interface sliding as illustrated by the multiple quaternary structures of liganded hemoglobin.
Biochemistry, 39:15353-15364, 2000

PubMed Abstract: Initial crystallographic studies suggested that fully liganded mammalian hemoglobin can adopt only a single quaternary structure, the quaternary R structure. However, more recent crystallographic studies revealed the existence of a second quaternary structure for liganded hemoglobin, the quaternary R2 structure. Since these quaternary structures can be crystallized, both must be energetically accessible structures that coexist in solution. Unanswered questions include (i) the relative abundance of the R and R2 structures under various solution conditions and (ii) whether other quaternary structures are energetically accessible for the liganded alpha(2)beta(2) hemoglobin tetramer. Although crystallographic methods cannot directly answer the first question, they represent the most direct and most accurate approach to answering the second question. We now have determined and refined three different crystal structures of bovine carbonmonoxyhemoglobin. These structures provide clear evidence that the dimer-dimer interface of liganded hemoglobin has a wide range of energetically accessible structures that are related to each other by a simple sliding motion. The dimer-dimer interface acts as a "molecular slide bearing" that allows the two alpha beta dimers to slide back and forth without greatly altering the number or the nature of the intersubunit contacts. Since the general stereochemical features of this interface are not unusual, it is likely that interface sliding of the kind displayed by fully liganded hemoglobin plays important structural and functional roles in many other protein assemblies.

PubMed: 11112521
DOI: 10.1021/bi0012944

Experimental method

X-RAY DIFFRACTION (1.9 Å)