[Induction by formaldehyde of conformational changes from helix to globule in the myoglobin molecule]

The secondary structure of myoglobin, treated with formaldehyde, has been studied by absorption spectroscopy, circular dichroism and gel-chromatography. The chemical modification of protein leads to disturbance of the polypeptide alpha-helix and destruction of the heme environment. The unfolding of protein in the presence of formaldehyde is a reversible process, the rate of transition is conditioned by temperature and formaldehyde concentration. At certain temperature conditions and formaldehyde concentration it is possible to obtain completely unfolded protein. The denaturation of myoglobin in the presence of formaldehyde is not cooperative in contrast to classical denaturation by pH, temperature, urea and other agents. Presence of some aminoacids causes inhibition of conformational changes in the protein molecule. Possible mechanisms of denaturation of myoglobin in the presence of formaldehyde are discussed.