Paper Citing NAMD - Abstract
Di Rocco, Giulia; Battistuzzi, Gianantonio; Borsari, Marco; De Rienzo, Francesca; Ranieri, Antonio; Tutino, Maria Luisa; Sola, Marco
Cloning, expression and physicochemical characterization of a di-heme cytochrome c(4) from the psychrophilic bacterium Pseudoalteromonas haloplanktis TAC 125
JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY, 13:789-799, JUN 2008
The 20-kDa di-heme cytochrome c(4) from the psycrophilic bacterium Pseudoalteromonas haloplanktis TAC 125 was cloned and expressed in Escherichia coli and investigated through UV-vis and (1)H NMR spectroscopies and protein voltammetry. The model structure was computed using the X-ray structure of Pseudomonas stutzeri cytochrome c(4) as a template. The protein shows unprecedented properties within the cytochrome c(4) family, including (1) an almost nonpolar surface charge distribution, (2) the absence of high-spin heme Fe(III) states, indicative of a thermodynamically stable and kinetically inert axial heme His,Met coordination, and (3) identical E degrees' values for the two heme centers (+0.322 V vs the standard hydrogen elecrode). At pH extremes, both heme groups undergo the "acid" and "alkaline" conformational transitions typical of class I cytochromes c, involving ligand-exchange equilibria, whereas at intermediate pH values their electronic properties are sensitive to several residue ionizations.
