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. 1987 Jun;84(11):3714–3717. doi: 10.1073/pnas.84.11.3714

Isolation and partial purification of an enzyme catalyzing the formation of O-xylosylzeatin in Phaseolus vulgaris embryos

Janet E Turner *, David W S Mok *, Machteld C Mok *, Gordon Shaw †
PMCID: PMC304946  PMID: 16593839

Abstract

An enzyme catalyzing the formation of a cytokinin metabolite, an O-pentosyl derivative of zeatin [Lee, Y. H., Mok, M. C., Mok, D. W. S., Griffin, D. A. & Shaw, G. (1985) Plant Physiol. 77, 635-641], was isolated from Phaseolus vulgaris embryos. Of all the potential pentose donors tested, UDP-xylose was the only substrate recognized by the enzyme. This indicates that the O-pentosyl derivatives previously obtained are O-xylosylzeatin and its ribonucleoside. The enzyme (UDP-xylose:zeatin O-xylosyltransferase, EC 2.4.2.-) has high affinity for trans-zeatin (Km 2 μM) and dihydrozeatin (Km 10 μM) but does not recognize cis-zeatin or ribosylzeatin. The molecular weight of the enzyme is approximately 50,000 and the pH optimum of the reaction is 8-8.5. Under comparable isolation and reaction conditions, similar enzyme activity could not be detected in P. lunatus embryos, confirming the genetic differences observed in vivo.

Keywords: cytokinin, phytohormones, beans, legumes

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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