for small molecules , such as cysteine , n-acetylcysteine , glutathione , and 2-mercaptoethanol , the spectrum is that of a freely rotating nitroxide while for the proteins , bovine serum albumin and myosin , the spectrum is characteristic of a strongly immobilized nitroxide spin label rigidly attached to the protein .
C0010654
cysteine
C0001047
n-acetylcysteine