Studio della reattività di due emoglobine non simbiotiche di Arabidopsis thaliana: ruolo della dinamica e della struttura proteica

In this doctorate thesis the study of the reactivity of the two non symbiotic haemoglobins is presented of Arabidopsis thaliana AHb1 and AHb2, characterized by intramolecular esacoordination of the hemic iron atom in absence of exogenous ligands. Particularly the rebinding of the ligand diatomic monoxide of carbon has been studied after photolysis realized on the COAHbs through an impulse of laser light to 532 nm. The laser flash photolysis is the used technique. The measures of LFP and the numerical analysis associated furnish a detailed analysis of the reactivity of AHb1 and AHb2 towards the CO, whose kinetics of rebinding have been measured to vary of different physical and chemist parameters such as viscosity and temperature, using as well the immobilization technique inside nanoporosis silica gel. The different effects of these experimental conditions on the kinetics of rebinding to the two proteins suggest a different role of the protein dynamics on the reactivity. Under conditions of high viscosity, the kinetics of rebinding of the CO to AHb1 suggests the presence of migration processes of the ligand photodissociated through a series of sites of temporary stockage. On the other hand, the rebinding to AHb2 is very influenced by the dynamics of the protein, while the effects produced by the migration seem to be small.