Partial Purification of a cis-trans-Isomerase of Zeatin from Immature Seed of Phaseolus vulgaris L.
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[deg] 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.
Bassil
N. V.
NV
Department of Horticulture and Center for Gene Research and Biotechnology, Oregon State University, Corvallis, Oregon 97331.
Mok
DWS.
D
Mok
M. C.
MC