Galactomannan degrading enzymes in maturing normal and makapuno and germinating normal coconut endosperm

Abstract

β-Mannosidase activity in the maturing normal endosperm of coconut decreased from 1.40 milliunit/mg protein at 7–8 months to 0.29 milliunit/mg protein at 11–12 months. It was 6–10 times lower at 7–8 and 8–9 months and was not detected at the more mature stages of makapuno. In contrast, the liquid endosperm from normal nuts increased in α- d-galactosidase, β-mannanase and β-mannosidase activity as development progressed. In makapuno liquid endosperm, the values for all the enzymes were consistently low during endosperm maturation. During germination, α- d-galactosidase activity in the solid endosperm increased from 0.51–0.84 unit/mg protein. β-Mannanase and β-mannosidase activity increased from 33.12 to 67.76 milliunit/mg protein and 5,13 to 43.05 milliunit/mg protein, respectively. In the haustorium, α- d-galactosidase activity remained at 0.25–0.27 unit/mg protein while β-mannanase increased from 55.34 to 138.12 milliunit/mg protein. β-Mannosidase decreased from 371.79 to 165.17 milliunit/mg protein. The implications of enzyme levels of α- d-galactosidase, β- d-mannanase and β- d-mannosidase on the mode of galactomannan degradation in the developing and germinating nut and phenotype determination of both normal and makapuno nuts are discussed.