[Thermodynamic behaviour and conformational changes of alcohol oxidase of yeasts Hansenula polymorpha].

We studied influence of heating, ethanol and sodium azide on the structural and conformational changes of the alcohol oxidase from yeast Hansenula polymorpha. The increase of fluorescence of alcohol oxidase -cofactor, flavin adenine dinucleotide, was revealed when heated to 60 degrees C while the enzymatic activity of alcohol oxidase remained unchanged. Differential scanning microcalorimetry revealed that ethanol stabilized the protein structure and increased the temperature of melting, Based on the data of circular dichroism, we concluded that the percentage of helicities in the secondary structure of alcohol oxidase was not influenced by both ethanol and sodium azide, however ethanol significantly modified the circular dichroism spectrum associated with the tertiary structure of alcohol oxidase.