title: Correlation between functional and structural changes of reduced and oxidized trout hemoglobins I and IV at different pHs. A circular dichroism study.
abstract: Circular dichroism (CD) spectra of two major hemoglobin components (Hb), HbI and HbIV, from Oncorhyncus mykiss (formerly Salmo irideus) trout were evaluated in the range 250-600 nm. HbI is characterized by a complete insensitivity to pH changes, while HbIV presents the Root effect. Both reduced [iron(II) or oxy] and oxidized (met) forms of the two proteins were studied at different pHs, 7.8 and 6.0, to obtain information about the pH effects on the structural features of these hemoglobins. Data obtained show that oxy and met-HbI are almost insensitive to pH decrease, remaining in the R conformational state also at low pH. On the contrary, the pH decrease induces similar structural changes, characteristics of ligand dissociation and R-->T transition, both in the reduced and in the oxidized HbIV. The structural changes, monitored by CD, are compared with the peroxidative activity of iron(II)-Hb and met-Hb forms and with the superoxide anion scavenger capacity of the proteins.
authors.affiliation: Dipartimento di Biologia M.C.A., Università di Camerino, Camerino, Italy. rosita.gabbianelli@unicam.it
authors.forename: Rosita
authors.initials: R
authors.lastname: Gabbianelli
authors.forename: Giovanna
authors.initials: G
authors.lastname: Zolese
authors.forename: Enrico
authors.initials: E
authors.lastname: Bertoli
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Falcioni
mesh_terms: D000166:Acridines / Q000378:metabolism; D000818:Animals; D002942:Circular Dichroism; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D006139:Guaiacol / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism*; D006455:Hemoglobins, Abnormal / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008163:Luminescent Measurements; D017686:Oncorhynchus mykiss / Q000097:blood*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D011487:Protein Conformation; D013223:Statistics as Topic; D019820:Xanthine / Q000378:metabolism; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D000166:Acridines; D005296:Ferrous Compounds; D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D019820:Xanthine; C033472:10,10'-dimethyl-9,9'-biacridinium; D006139:Guaiacol; D009195:Peroxidase; D014969:Xanthine Oxidase