PMID- 23280541
OWN - NLM
STAT- MEDLINE
DCOM- 20130918
LR  - 20151119
IS  - 1097-0134 (Electronic)
IS  - 0887-3585 (Linking)
VI  - 81
IP  - 5
DP  - 2013 May
TI  - Quaternary structure effects on the hexacoordination equilibrium in rice 
      hemoglobin rHb1: insights from molecular dynamics simulations.
PG  - 863-73
LID - 10.1002/prot.24245 [doi]
AB  - Nonsymbiotic hemoglobins (nsHbs) form a widely distributed class of plant 
      proteins, which function remains unknown. Despite the fact that class 1 plant 
      nonsymbiotic hemoglobins are hexacoordinate (6c) heme proteins (hxHbs), their 
      hexacoordination equilibrium constants are much lower than in hxHbs from animals 
      or bacteria. In addition, they are characterized by having very high oxygen 
      affinities and low oxygen dissociation rate constants. Rice hemoglobin 1 (rHb1) 
      is a class 1 nonsymbiotic hemoglobin. It crystallizes as a fully associated 
      homodimer with both subunits in 6c state, but showing slightly different 
      conformations, thus leading to an asymmetric crystallographic homodimer. The 
      residues that constitute the dimeric interface are conserved among all nsHbs, 
      suggesting that the quaternary structure could be relevant to explain the 
      chemical behavior and biological function of this family of proteins. In this 
      work, we analyze the molecular basis that determine the hexacoordination 
      equilibrium in rHb1. Our results indicate that dynamical features of the 
      quaternary structure significantly affect the hexacoordination process. 
      Specifically, we observe that the pentacoordinate state is stabilized in the 
      dimer with respect to the isolated monomers. Moreover, the dimer behaves 
      asymmetrically, in a negative cooperative scheme. The results presented in this 
      work are fully consistent with our previous hypothesis about the key role played 
      by the nature of the CD region in determining the coordination state of globins.
CI  - Copyright (c) 2013 Wiley Periodicals, Inc.
FAU - Morzan, Uriel N
AU  - Morzan UN
AD  - Departamento de Quimica Inorganica, Analitica y Quimica Fisica/ INQUIMAE-CONICET, 
      Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos 
      Aires, Argentina.
FAU - Capece, Luciana
AU  - Capece L
FAU - Marti, Marcelo A
AU  - Marti MA
FAU - Estrin, Dario A
AU  - Estrin DA
LA  - eng
PT  - Journal Article
DEP - 20130228
PL  - United States
TA  - Proteins
JT  - Proteins
JID - 8700181
RN  - 0 (Plant Proteins)
RN  - 9004-22-2 (Globins)
SB  - IM
MH  - Globins/*chemistry
MH  - Molecular Dynamics Simulation
MH  - Oryza/*chemistry
MH  - Plant Proteins/*chemistry
MH  - Protein Conformation
MH  - Protein Multimerization
MH  - Protein Structure, Quaternary
MH  - Thermodynamics
EDAT- 2013/01/03 06:00
MHDA- 2013/09/21 06:00
CRDT- 2013/01/03 06:00
PHST- 2012/07/13 00:00 [received]
PHST- 2012/12/11 00:00 [revised]
PHST- 2012/12/14 00:00 [accepted]
PHST- 2013/01/03 06:00 [entrez]
PHST- 2013/01/03 06:00 [pubmed]
PHST- 2013/09/21 06:00 [medline]
AID - 10.1002/prot.24245 [doi]
PST - ppublish
SO  - Proteins. 2013 May;81(5):863-73. doi: 10.1002/prot.24245. Epub 2013 Feb 28.