Electron transfer in potassium collisions with the simplest amino acid glycine has been investigated in the energy range from 20 to 100 eV. In the unimolecular decomposition, fragmentation patterns obtained through TOF mass spectrometry show peculiar differences in comparison with dissociative electron attachment measurements. The most prominent feature in the collision regime is the relative decrease of the dehydrogenated parent anion signal with respect to the hydrogen anion as the collision energy increases. For low collision energies this can be rationalized in terms of autodetachment inhibition, whereas at higher collisions energies the negative molecular ion can be formed with an excess of internal energy which might even result in fragmentation. Metastable decay is here suggested to play a particular role leading to the formation of three anions assigned in the light of recent dissociative electron attachment studies. The formation of isobaric fragments with masses 15, 16 and 26 a.m.u. is also discussed on the basis of the energy available in the electron transfer process.