Studies on fructosyl transferase from Agave americana

The possible role of fructosyl transferase in the biosynthesis of fructosans in Agave americana was investigated. This enzyme was extracted from A. americana stem and purified 17.5-fold by salt fractionation and DEAE-cellulose chromatography. The optimum conditions for the enzyme were pH 6. 1, temperature 37°, substrate concentration 20% and K_m 3.6 × 10^?1 M; Ag⁺, Pb ²⁺, Hg²⁺, Al³⁺, Sn²⁺, CN^? acted as inhibitors and Ca²⁺, Mg²⁺, Co²⁺ and Li⁺ actemd as activators. Only sugars of the type F ～ R (R-aidose), e.g. sucrose and raffinose acted as substrates for the enzyme. The donor acceptor specificity of the enzyme was studied extensively. Sugars sucrose. None of the intermediates of fructosan biosynthesis from sucrpse acted as fructose donors. The possible acceptors from sucrose and raffinose. The enzyme was capable of building up oligosaccharides up to FIOG from sucrose. None of the intermediates of fructosan biosynthesis from sucrose acted as fructose donors. The possible mechanism of fructosan biosynthesis from sucrose is discussed.