Cytokinin binding proteins from mammalian sera.

ABSTRACT

A cytokinin-binding protein fraction was isolated from normal rabbit sera by affinity chromatography. The protein fraction bound tritium labelled N6- (Δ2-risopentenyl) adenosine and the order of inhibition of this binding by competing non-radioactive compounds was, N6-(Δ2-isopentenyl) adenosine >N6-benzyIadenosine >zeatin-riboside >N6-(Δ2-isopentenyl) adenine >kinetin riboside >adenosine. The protein fraction showed broad specificity, the prefered cytokinin being N6-(Δ2-isopentenyl) adenosine. This is the first report of the isolation of cytokinin binding proteins from mammalian sources.