MODIFICATION OF HORSE HEART CYTOCHROME-C WITH TRANS-2-HEXENAL

Horse heart cytochrome c reacting with trans-2-hexenal was used as a s imple model of the nonspecific interactions of proteins with 2-alkenal s. The reaction mixtures containing relatively high concentrations of the protein and aldehyde were characterized using visible spectrophoto metry, fluorescence, and circular dichroism measurements, capillary is oelectric focusing, size-exclusion chromatography, polyacrylamide gel electrophoresis, and mass-spectrometric techniques. The mass-spectrome tric data indicate that cytochrome c becomes modified with one or two molecules of hexenal as the major reaction product. The modified speci es with a correspondingly lowered isoelectric point were detected thro ugh capillary isoelectric focusing. The results of proteolytic studies indicate nonspecific modifications. Significant quantities of the oli gomeric farms of hexenal-modified protein were also observed electroph oretically.