Papain is a plant proteolytic enzyme for the cysteine proteinase family cysteine protease enzyme in which enormous progress has been made to understand its functions. Papain is found naturally in papaya (Carica papaya L.) manufactured from the latex of raw papaya fruits. The enzyme is able to break down organic molecules made of amino acids, known as polypeptides and thus plays a crucial role in diverse biological processes in physiological and pathological states, drug designs, industrial uses such as meat tenderizers and pharmaceutical preparations. The unique structure of papain gives it the functionality that helps elucidate how proteolytic enzymes work and also makes it valuable for a variety of purposes. In the present review, its biological importance, properties and structural features that are important to an understanding of their biological function are presented. Its potential for production and market opportunities are also discussed.

Abstract:Brazzein is a small sweet-tasting 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 in 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 29 and 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.