Stability of some cactaceae proteins based on fluorescence, circular dichroism, and differential scanning calorimetry measurements

Characterization of three cactus proteins (native and denatured) from Macha erocereus gummosus (Pitahaya agria), Lophocereu schottii (Garambullo), and Cholla opuntia (Cholla), was based on electrophoretic, fluorescence, CD (ci rcular dichroism), DSC (differential scanning calorimetry), and FT-IR (Four ier transform infrared) measurements. The obtained results of intrinsic flu orescence, DSC, and CD were dissimilar for the three species of cactus, pro viding evidence of differences in secondary and tertiary structures. Cactus proteins may be situated in the following order corresponding to their rel ative stability: Machaerocereus gummosus (Pitahaya agria) > Cholla opuntia (Cholla) > Lophocereu schottii (Garambullo). Thermodynamic properties of pr oteins and their changes upon denaturation (temperature of denaturation, en thalphy, and the number of ruptured hydrogen bonds) were correlated with th e secondary structure of proteins and disappearance of alpha-helix.