INVESTIGADORES
ESTRIN Dario Ariel
artículos
Título:
H-bonding networks of the distal residues and water molecules in the active site of Thermobifida fusca hemoglobin
Autor/es:
NICOLETTI, F.P.; DROGHETTI, E.; HOWES, B.; J.P. BUSTAMANTE; BONAMORE, A.; SCIAMANNA, N.; ESTRIN, D.A.; FEIS, A.; BOFFI, A.; G. SMULEVICH
Revista:
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2013 vol. 1834 p. 1901 - 1909
ISSN:
1570-9639
Resumen:
The ferric form of truncated hemoglobin II from Thermobifida fusca
(Tf-trHb) and its triple mutant WG8F-YB10F-YCD1F at neutral and alkaline
pH, and in the presence of CN- have been characterized by
resonance Raman spectroscopy, electron paramagnetic resonance
spectroscopy, and molecular dynamics simulations. Tf-trHb contains three
polar residues in the distal site, namely TrpG8, TyrCD1 and TyrB10.
Whereas TrpG8 can act as a potential hydrogen-bond donor, the tyrosines
can act as donors or acceptors. Ligand binding in heme-containing
proteins is determined by a number of factors, including the nature and
conformation of the distal residues and their capability to stabilize
the heme-bound ligand via hydrogen-bonding and electrostatic
interactions. Since both the RR Fe-OH- and Fe-CN-
frequencies are very sensitive to the distal environment, detailed
information on structural variations has been obtained. The hydroxyl
ligand binds only the WT protein giving rise to two different
conformers. In form 1 the anion is stabilized by H-bonds with TrpG8,
TyrCD1 and a water molecule, in turn H-bonded to TyrB10. In form 2,
H-bonding with TyrCD1 is mediated by a water molecule. Unlike the OH- ligand, CN-
binds both WT and the triple mutant giving rise to two forms with
similar spectroscopic characteristics. The overall results clearly
indicate that H-bonding interactions both with distal residues and water
molecules are important structural determinants in the active site of
Tf-trHb.