An Alpha Amylase Like Protein from Plantains

Abstract

Carbohydrates and lignocellulose biomass are the major feedstock for the bioethanol production. The processing of starch to bioethanol is a challenging process that requires several agents and varying conditions. The starch liquefaction and saccharification are key processing steps in the bioethanol industry. The rate-limiting α-amylase plays an important role due to its endo-glycosidic activity. α-amylase endo-glycosidic action on long glucan chains may be rate limiting in starch. The purpose of this study is to purify an alpha amylase from plantains. Water soluble proteins were extracted from fully ripened plantains, and α-amylase activities were measured. It was observed that there is a strong variation in α-amylase activities among individual plantains, although the protein concentration was generally low. The proteins were fractionated using ammonium sulphate, the α-amylase precipitated at 30% of the salt. This is characteristically low and desirable since most proteins precipitate at higher ammonium sulphate concentration. It suggested that majority of contaminating proteins and other molecules may be removed in the single step; dialysis was used to remove the salt. Consequently, significant enrichment in α-amylase activity was recovered after dialysis. Subsequent purification of the protein was attempted using ion exchange chromatography. The protein binds to Q-sepharose at neutral pH but this was not successful at acidic pH. Therefore, the result revealed that the protein could be negatively charged at that condition. Hence, a new alpha amylase like protein was purified from plantains.