A vibrational spectroscopic assignment of the disulfide bridges in recombinant bovine growth hormone and growth hormone analogs

Disulfide stretching vibrations for bovine growth hormone (bGH) occur in a vibrational envelope centered at 540 cm(-1) which spans 480-580 cm(-1). A m ultitude of vibrational bands present in this envelope, that are not relate d to cm disulfide stretching, emphasize the need for model compounds when a ssigning S-S stretching modes. Raman spectroscopic data for bGH analogs, in which one or both of the two disulfide bridges have been selectively cleav ed, have been used to characterize the S-S stretching envelope for the two cystine links in bcH. The Raman data for the r-bGH analogs indicate that th e number of disulfide bonds present in r-bGH is determined, not by the obse rvance of the presence or absence of a single spectral peak, but by the rel ative intensity of vibrational envelope from 520-560 cm(-1). Cleavage of di sulfide bridges in bGH results in a general decrease in vibrational spectra l intensity in the 520-560 cm(-1) range. This decrease in intensity is prop ortional to the number of cystine links severed. (C) 1999 Elsevier Science B.V. All rights reserved.