Partial purification of a cis-trans-isomerase of zeatin from immature seed of Phaseolus vulgaris L
1993
Bassil, N.V. | Mok, D.W.S. | Mok, M.C.
Investigation of the conversion of exogenous cis-zeatin to trans-zeatin in immature seeds of Phaseolus vulgaris L. led to the isolation of a cis-trans-isomerase from the endosperm. The enzyme was purified more than 2000-fold by chromatography on a series of fast protein liquid chromatography (anion exchange, gel filtration, and hydrophobic interaction) and concanavalin A columns. The enzymic reaction favors conversion from the cis to the trans form and requires flavin, light, and dithiothreitol, cis-zeatin riboside is also a substrate for the enzyme. Retention on the concanavalin A column indicated that the enzyme is a glycoprotein. The enzyme was stable for at least 8 weeks when stored at 80 degrees C. The occurrence of cis-trans-isomerization suggests that cis-zeatin and cis-zeatin riboside formed by tRNA degradation could be precursors of biologically active cytokinins.
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