The structure—activity relationships of the sweet protein brazzein — roles of acidic amino acids

Abstract

Brazzein is a thermostable, sweet-tasting protein isolated from the fruit of the African plant, Pentadiplandra brazzeana Baillon [1]. Brazzein consists of 54 amino acid residues and has four intramolecular disulfide bonds [2]. It is wellknown that the carboxyl groups of sweet compounds participate in binding with the receptor. Brazzein contains five Asp residues at positions 2, 25, 29, 40 and 50, and four Glu residues at positions 9, 36, 41 and 53. The roles of these acidic amino acids were investigated by replacing each with an Ala residue by the fluoren-9-yl-methoxycarbonyl (Fmoc) solid-phase synthesis.