http://www.cnr.it/ontology/cnr/individuo/prodotto/ID168710
An order-disorder transition plays a role in switching off the Root effect in fish hemoglobins (Articolo in rivista)
- Type
- Label
- An order-disorder transition plays a role in switching off the Root effect in fish hemoglobins (Articolo in rivista) (literal)
- Anno
- 2010-01-01T00:00:00+01:00 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
- 10.1074/jbc.M110.143537 (literal)
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- Vergara A.; Vitagliano L.; Merlino A.; Sica F.; Marino K.; Verde C.; di Prisco G.; Mazzarella L. (literal)
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- Note
- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- Department of Chemistry, University of Naples \"Federico II,\" Naples I-80126, Italy, the Istituto di Biostrutture e
Bioimmagini, CNR, Naples I-80134, Italy, and Institute of Protein Biochemistry, CNR, Naples I-80131, Italy (literal)
- Titolo
- An order-disorder transition plays a role in switching off the Root effect in fish hemoglobins (literal)
- Abstract
- The Root effect is a widespread property among fish hemoglobins whose structural basis remains largely obscure. Here we report a crystallographic and spectroscopic characterization of the non-Root-effect hemoglobin isolated from the Antarctic fish Trematomus newnesi in the deoxygenated form. The crystal structure unveils that the T state of this hemoglobin is stabilized by a strong H-bond between the side chains of Asp95± and Asp101² at the ±(1)²(2) and ±(2)²(1) interfaces. This unexpected finding undermines the accepted paradigm that correlates the presence of this unusual H-bond with the occurrence of the Root effect. Surprisingly, the T state is characterized by an atypical flexibility of two ± chains within the tetramer. Indeed, regions such as the CD± corner and the EF± pocket, which are normally well ordered in the T state of tetrameric hemoglobins, display high B-factors and non-continuous electron densities. This flexibility also leads to unusual distances between the heme iron and the proximal and distal His residues. These observations are in line with Raman micro-spectroscopy studies carried out both in solution and in the crystal state. The findings here presented suggest that in fish hemoglobins the Root effect may be switched off through a significant destabilization of the T state regardless of the presence of the inter-aspartic H-bond. Similar mechanisms may also operate for other non-Root effect hemoglobins. The implications of the flexibility of the CD± corner for the mechanism of the T-R transition in tetrameric hemoglobins are also discussed. (literal)
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