Nv. Bassil et al., PARTIAL-PURIFICATION OF A CIS-TRANS-ISOMERASE OF ZEATIN FROM IMMATURESEED OF PHASEOLUS-VULGARIS L, Plant physiology, 102(3), 1993, pp. 867-872
Investigation of the conversion of exogenous cis-zeatin to trans-zeati
n 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 ch
romatography (anion exchange, gel filtration, and hydrophobic interact
ion) and concanavalin A columns. The enzymic reaction favors conversio
n from the cis to the trans form and requires flavin, light, and dithi
othreitol. cis-Zeatin riboside is also a substrate for the enzyme. Ret
ention on the concanavalin A column indicated that the enzyme is a gly
coprotein. 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.