TAILIEUCHUNG - Báo cáo khoa học: Correlation between functional and structural changes of reduced and oxidized trout hemoglobins I and IV at different pHs

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, and , to obtain information about the pH effects on the structural features of these hemoglobins. | Eur. J. Biochem. 271 1971-1979 2004 FEBS 2004 doi Correlation between functional and structural changes of reduced and oxidized trout hemoglobins I and IV at different pHs A circular dichroism study Rosita Gabbianelli1 Giovanna Zolese2 Enrico Bertoli2 and Giancarlo Falcioni1 1 Dipartimento di Biologia . Universita di Camerino Camerino Italy 2Istituto di Biochimica Facolta di Medicina Universita Politecnica delle Marche Ancona Italy 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. Hbl is characterized by a complete insensitivity to pH changes while HblV presents the Root effect. Both reduced iron II or oxy and oxidized met forms of the two proteins were studied at different pHs and 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 fi 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. Keywords trout hemoglobin derivatives hemoglobin peroxidase activity superoxide anion circular dichroism pH effect. The hemoglobin system of the Oncorhyncus mykiss formerly Salmo irideus trout is made up of four electro-phoretically distinct components two of which trout hemoglobin Hb I w 20 and trout HbIV 60 represent quantitatively a large fraction of the whole pigment. In the last years the properties of these two major components HbI and HbIV have been investigated in considerable detail under various experimental conditions 1 2 . Their structural

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