Analysis of aluminum-yeast hexokinase interaction: Modifications on protein structure and functionality

The aluminum and yeast hexokinase interaction was studied. Structural chang es were correlated with variations in protein functionality. Results show t wo different behaviors: At low metal concentrations preferential adsorption of metal land water exclusion) induces aggregate formation. No significant changes in the protein structure occur, but there is a continuous loss of activity (from the first concentration). At large salt concentrations a mon omerization process and a conformational change in the secondary structure as well as in the three-dimensional structure take place. This change reduc es the percentage of alpha-helix conformation, gives thermal stability to t he protein, and allows the exposure of some tryptophan residue and hydropho bic regions. The protein inhibition increases. Conformational change and mo nomerization may allow access of the metal to the substrate site, mainly th e RTP site. The inhibition in any case is of mixed type with a competitive component.