Purification and Biochemical Characterization of Cell Wall-bound Trehalase from Pericarp Tissues of Actinidia deliciosa

Abstract

A trehalase (EC 3.2.1.28) was purified from the cell walls of Actinidia deliciosa fruit. The purified trehalase had optimal pH of around 5, Km of 0.25 mM and Vmax of 5667 pkat/mg protein, and was relatively heat stable. The enzyme showed highly specific activity to trehalose and weak activity to maltose and maltotriose, but did not hydrolyze any other disaccharides. Trehalase activity was unaffected by Ca²⁺, Na⁺, K⁺, Li⁺, Mn²⁺, Co²⁺, and Mg²⁺ ions and EDTA, but markedly inhibited by Hg²⁺ and Fe³⁺ ions, iodoacetic acid, tris(hydroxymethyl)aminomethane (Tris), p-chloromercuribenzoate (PCMB), glucose and glucosamine. This cell wall-bound enzyme seems to degrade apoplastic trehalose. Another possibility is that this trehalase has additional functions such as defence against insects.