Insights into Carbon Content in Examining the Effect of Mutation in Brazzein, a Sweet Tasting Protein

Brazzein is a small sweet testing protein isolated from the fruit of the African plant, Pentadiplandra brazzeana Baillon with potential of replacement of carbohydrate sweeteners. Carbon content analysis was used to examine the effect of mutation brazzein’s two regions at residues 29–33 and 39–43 with residue 36 reported to be important in sweet tasting of the protein. Analysis for local carbon density at the mutational sites for brazzein mutants with increased sweetness taste at residues 29and 41 revealed normal carbon distribution curves with increased carbon frequency peak compared to the wild-type, consequently stabilized the local structure. Brazzein mutants with reduced sweetness taste at residue position 30 33, 36 and 43 were mostly characterized by abnormal broadened distribution curve for carbon content with decreased frequency peak which destabilized the local structure and possibly leading to loss of protein functionality. Further analysis of carbon distribution profile along protein sequences of brazzein revealed a variation in carbon distribution between mutants with increased sweetness taste and those with decreased sweetness taste. Mutants with increased sweetness taste had carbon distribution profile balancing well conforming to the globular proteins which prefers to have 31.45% of carbon all along the sequence for stability. This study has provided further information and additional insights into protein atomic composition in brazzein and its role in understanding the effect of mutation.