This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (66) Citing Articles via Google Scholar Google Scholar Articles by Thayer, S. S. Articles by Conn, E. E. Search for Related Content PubMed PubMed Citation Articles by Thayer, S. S. Articles by Conn, E. E. Agricola Articles by Thayer, S. S. Articles by Conn, E. E.

Articles

Subcellular Localization of Dhurrin -Glucosidase and Hydroxynitrile Lyase in the Mesophyll Cells of Sorghum Leaf Blades ¹

Department of Biochemistry and Biophysics, University of California, Davis, California 95616

Studies with purified mesophyll and epidermal protoplasts and bundle sheath strands have shown that the cyanogenic glucoside dhurrin (p-hydroxy-(S)-mandelonitrile--D-glucoside) is localized in the epidermis of sorghum leaves whereas the enzymes involved in its degradation (dhurrin -glucosidase and hydroxynitrile lyase) are localized in the mesophyll tissue (Kojima M, JE Poulton, SS Thayer, EE Conn 1979 Plant Physiol 63: 1022-1028). The subcellular localization of these enzymes has now been examined using linear 30 to 55% (w/w) sucrose gradients by fractionation of mesophyll protoplast components. The hydroxynitrile lyase is found in the supernatant fractions suggesting a cytoplasmic (soluble cytoplasm, microsomal or vacuolar location). The dhurrin -glucosidase (dhurrinase) is particulate and mostly chloroplast-associated. The dhurrinase activity peak has a shoulder of activity more dense than that of the intact chloroplasts. This shoulder does not coincide with markers of any other cell fraction.

In studies of chloroplasts isolated from ruptured mesophyll protoplasts by differential, low-speed centrifugation, the dhurrinase partitions in the same manner as the chloroplast marker triose phosphate dehydrogenase. Chloroplast localization of the -glucosidase has also been shown in histochemical studies using 6-bromo-2-naphthyl--D-glucoside substrate coupled with fast Blue B.

This article has been cited by other articles:

				A. V. Morant, N. Bjarnholt, M. E. Kragh, C. H. Kjaergaard, K. Jorgensen, S. M. Paquette, M. Piotrowski, A. Imberty, C. E. Olsen, B. L. Moller, et al. The {beta}-Glucosidases Responsible for Bioactivation of Hydroxynitrile Glucosides in Lotus japonicus Plant Physiology, July 1, 2008; 147(3): 1072 - 1091. [Abstract] [Full Text] [PDF]

				M. Cicek and A. Esen Structure and Expression of a Dhurrinase (beta -Glucosidase) from Sorghum Plant Physiology, April 1, 1998; 116(4): 1469 - 1478. [Abstract] [Full Text]