Extraction and Activity of Polyphenol Oxidase from Kolanuts (Cola nitida and Cola acuminata) and Cocoa (Theobroma cacao)

Abstract

The activity of polyphenol oxidase was investigated in kolanuts (Cola nitida and Cola acuminata) as well as cocoa (Theobroma cacao). Spectrophotometric method was used to assay the enzyme activity and the kinetic constants - maximum enzyme velocity (Vmax) and Michealis - Menten constant (Km). The maximum enzyme activity (Vmax) for the three plant species were 1.1 x10-3 O.D/Sec, 1.5 x 10-4 O.D/Sec and 2.5 x 10-3 O.D/Sec for C. nitida, C. acuminata and T. Cacao respectively. The Michealis – Menten's constant (Km) were 9.1x10-4M, 9.1x10-4M and 5.0x10-3M for C.nitida, C.acuminata and T.cacao respectively. The variation in maximum enzyme activity (Vmax) reflects interspecies differences in the absolute quantity of enzyme present in the three plant tissues. However, the km values were the same for the two species of kolanuts but varied when compared with the km value of enzyme extract of T. Cacao. The differences in km and Vmax values showed that there are variations in the physicochemical characteristics and absolute quantity of polyphenol oxidase present in the three plant species.

Journal of Agriculture and Food Sciences Vol. 4 (2) 2006: pp. 115-124