On annealing at temperatures near 100 degrees C, carbon-centered radicals migrate to sulfur-centered radicals in X-irradiated crystals of L-alpha-amino-n-butyric acid hydrochloride, CH3CH2CH(NH3-Cl)COOH, containing L-cysteine hydrochloride, SHCH2CH(NH3Cl)COOH. Samples containing 0, 0.5, 1.0, and 1.5% L-cysteine hydrochloride were studied. When no cysteine is present, the carbon-centered radical...