Ligand- and proton-linked conformational changes of the ferrous 2/2 hemoglobin of Pseudoalteromonas haloplanktis TAC125
✍ Scribed by Daniela Giordano; Roberta Russo; Chiara Ciaccio; Barry D. Howes; Guido di Prisco; Michael C. Marden; Gaston Hui Bon Hoa; Giulietta Smulevich; Massimo Coletta; Cinzia Verde
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 182 KB
- Volume
- 63
- Category
- Article
- ISSN
- 1521-6543
- DOI
- 10.1002/iub.492
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✦ Synopsis
Abstract
The spectroscopic and ligand‐binding properties of a 2/2 globin from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 have been studied in the ferrous state. It displays two major conformations characterized by CO‐association rates that differ by a factor of 20, with relative fractions that depend on pH. A dynamic equilibrium is found between the two conformations, as indicated by an enhanced slower phase when lower CO levels were used to allow a longer time to facilitate the transition. The deoxy form, in the absence of external ligands, is a mixture of a predominant six‐coordinate low spin form and a five‐coordinate high‐spin state; the proportion of low spin increasing at alkaline pH. In addition, at temperatures above the physiological temperature of 1 °C, an enhanced tendency of the protein to oxidize is observed. © 2011 IUBMB IUBMB Life, 63(7): 566–573, 2011