Thermal properties of chemically modified cytochrome c

Differential scanning calorimetry was used as a probe to follow structural disturbances in cytochrome c with electrostatic modification. At 51.7% maleylation, the Td decreased 14.1 degrees C; however, relatively stable delta H values reflected minor structural variations. With 77.5 and 96.4% modification, a significant decrease in delta H was more indicative of major conformational change. On this basis, a critical labelling point was considered. Extensive maleylation (96.4%) did not result in complete cytochrome denaturation. In general, assessment of cytochrome thermal parameters by DSC provided a conformational perspective for the influence of specific electrostatic parameters on molecular integrity.