Electron Paramagnetic Resonance (EPR) was used to investigate the Tempyo spin label (3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy) as a report group for the interactions and the conformational changes of lyophilized bovine serum albumin (BSA) and bovine haemoglobin (BH), as function of pH. values in the range 2.5÷11. The EPR spectra are similar with those of other noncovalently spin label porphyrins in frozen solution at very low temperatures.

Noncovalent spin labelled proteins (ovalbumin, bovine serum albumin, hemoglobin and cytochrome c) were investigated in order to follow the different type of interactions between the nitroxide radical of 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy spin label and functional groups of heme and nonheme proteins as well as the pH influence on molecular motion of the label with respect to these proteins. EPR spectra were recorded at room temperature

Electron paramagnetic resonance spectroscopy was used to investigate the γ-radiation damage in the microcristalline powder form of two antiemetic drugs, namely 4-amino-5-chloro-N-[2-(diethylamino)ethyl]-2-methoxy benzamide monohydrochloride monohydrate (metoclopramide) and 9-tetrahydro-9-methyl-3-[( 2-methyl-1H-imidazol-1-yl) methyl]-4H-carbazol-4-one, monohydrochloride, dihydrate (odansetron). EPR measurements proved that both of them contained