Purification of a Soluble Cytockinin-binding Protein from Etiolated Mung Bean Seedlings.
A cytokinin-binding protein (CBP) was purified from a crude extract of etiolated mung bean seedlings by a protocol involving affinity chromatography on benzyladenine-linked Sepharose 4B, ion exchange chromatography on DEAE-Sephadex A50, and gel filtration on Sphacryl S-400. The molecular weight was estimatd to be about 200,000 by gel filtration. CBP appeared as two bands corresponding to molecular weights of about 45,000 and 48,000 on SDS-polyacrylamide gel electrophoresis. The dissociation constant for benzyladenine was 7.5 x 10(-7) M. (14)C-Benzyladenine-binding to CBP was reversible and could be inhibited by the addition of kinetin or trans-zeatin. Adenine, AMP, and ADP had no inhibitory effect on the binding of (14)C-benzyladenine to CBP but the addition of ATP to the assay mixture enhanced the binding.
a Institute of Biological Sciences, University of Tsukuba , Tsukuba , Ibaraki 305 , Japan.
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Sakai
a Institute of Biological Sciences, University of Tsukuba , Tsukuba , Ibaraki 305 , Japan.
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Kamel