Document Detail

Protein structure in the truncated (2/2) hemoglobin family.
MedLine Citation:
PMID:  17701548     Owner:  NLM     Status:  MEDLINE    
The discovery of protein sequences belonging to the widespread 'truncated hemoglobin' family has been followed in the last few years by extensive analyses of their three-dimensional structures. Truncated hemoglobins can be classified in three main groups, in light of their overall structural properties. The three groups adopt a 2-on-2 alpha-helical sandwich fold, based on four main alpha-helices of the classical 3-on-3 alpha-helical sandwich found in vertebrate and invertebrate globins. Each of the three groups displays sequence and structure specific features. Among these, a protein matrix tunnel system is typical of group I, a Trp residue at the G8 topological site is conserved in groups II and III, and residue TyrB10 is almost invariant in the three groups. Despite sequence variability in the heme distal site region, a strongly intertwined, but varied, network of hydrogen bonds stabilizes the heme ligand in the three protein groups. Fine mechanisms of ligand recognition and stabilization may vary based on group-specific distal site residues and on differing ligand diffusion pathways to the heme. Taken together, the structural considerations here presented underline that 'truncated hemoglobins' result from careful editing of the 3-on-3 alpha-helical globin sandwich fold, rather than from simple 'truncation' events. Thus, '2/2Hb' appears the most proper term to concisely address this protein family.
Alessandra Pesce; Marco Nardini; Mario Milani; Martino Bolognesi
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  IUBMB life     Volume:  59     ISSN:  1521-6543     ISO Abbreviation:  IUBMB Life     Publication Date:    2007 Aug-Sep
Date Detail:
Created Date:  2007-08-16     Completed Date:  2007-11-13     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  100888706     Medline TA:  IUBMB Life     Country:  England    
Other Details:
Languages:  eng     Pagination:  535-41     Citation Subset:  IM    
Department of Physics, CNR-INFM, University of Genova, Genova, Italy.
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MeSH Terms
Hemoglobins / chemistry*,  metabolism
Models, Molecular
Protein Binding
Proteins / chemistry*,  metabolism
Truncated Hemoglobins
Grant Support
Reg. No./Substance:
0/Hemoglobins; 0/Ligands; 0/Proteins; 0/Truncated Hemoglobins

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