Membrane-bound polyphenol oxidases and peroxidases from Metroxylon sagu: Changes in activity and isoenzyme profiles during maturation

Author: Galila Hassan Onsa ¹, Nazamid bin Saari ^1*, Azizah Osman ¹ and Shamsul Bahri ²

Received 8 December 2002, accepted 18 April 2003.

Abstract

Membrane-bound Polyphenol oxidases (mPPO: E.C.1.10.3.2) and peroxidases (mPOD: E.C.1.11.1.7) were isolated from membrane-fractions of Metroxylon sagu employing temperature-induced phase partitioning technique using Triton X-114. The specific activities in unit activity / mg protein and their isoenzyme profile were studied during maturation. The stages of maturity are the young stage (2-4 years old), pre-mature (5-8 years old) and mature stage (9-12 years old). The highest mPPO specific activity was observed at the top log section of young stage and then decreased by 3.0 and 25-fold at premature and mature stage, respectively. On the other hand, mPOD activity was found to be constant at the early stages of maturity up to the premature stage (4-6 years). mPOD activity then increased by 1.5 and 2.9-fold at premature and matured stage respectively. High mPOD activity at mature stage was associated with the appearance of new isoenzymes as well as intensification of the existing one. A change in the polypeptides during maturation was also observed.