Purification and Properties of Chalcone Synthase from Cell Suspension Cultures of Soybean

Incubation of soybean cell suspension cultures in B-5 medium containing 0.4 m sucrose caused induction of chalcone synthase (CHS) up to a specific activity of 8 |ikat/kg. CHS from these cultures was purified to apparent homogeneity by a 5-step procedure. Isoelectric focussing of pure CHS gave a major band at pH 5.45 and two weaker bands at pH 5.35 and 5.5. At least the bands at pH 5.35 and 5.45 had CHS activity. Analysis of pure CHS by two-dimensional electrophoresis gave a set of six proteins with a Mr o f 40 kDa and pis between 6.0 and 6.6. One-dimensional PAG E of CHS under non-denaturing conditions gave three closely spaced protein bands. A specific antibody was raised against soybean CHS which cross-reacted with parsley CHS. Attem pts to find synthesis o f deoxychalcone or of the corresponding 7,4'-dihydroxyflavanone with CHS of different purification stages and with various cofactors failed.