Effect of tartrate on the colchicine-binding activity in cultured carrot cell extract

Abstract

The colchicine-binding activity in carrot-cell extract was markedly enhanced and also stabilized by the addition of tartrate. The optimum temperature for the binding reaction in the presence of tartrate shifted to 41 °C from 30 °C in its absence. The apparent affinity constant in the presence of tartrate was 1.6 × 105l/mol at 37 °C which is much higher than the value obtained in the absence of tartrate. It was confirmed from the following evidence that the binding reaction in the presence of tartrate represented the colchicinetubulin interaction. 1. The reaction was inhibited by the preincubation with proteases and not with lumicolchicine. 2. The colchicine-binding component had a similar property to porcine brain tubulin in DEAE-Sephacel column chromatography and SDSpolyacrylamide gel electrophoresis.