Complementary Epr-raman Spectroscopy Investigations of Spin Labelled Hemoglobin

Interactions of spin label with hemic proteins might affect the spin label spectra and, in the same time, it is well known that the pH strongly influences the conformation of proteins leading to significant changes in the type and degree of these interactions. In the present work, noncovalent spin labelled hemoglobin with tempyo spin label was investigated in the pH range 2.5-11 in order to obtain useful informations related to the interaction between the nitroxide group and the active site (hem group) of hemoglobin. Complementary, Raman and SERRS investigations were performed in order to emphasize the characteristic spectrum of hemoglobin with the three proeminent bands, called ‘’markers” of the hemic group, packed in the polypeptidic chain. These bands are assigned to ‘’in plane” vibration of the porphyrinic ring. It was concluded that these techniques are invaluable tools for probing microscopic molecular motions in biomolecules and, in the same time emphasize the selective character of SERRS techniques, using the adsorption of hemoglobin on silver colloidal soil.