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 PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Saunders, J. A. Articles by Gillespie, J. M. Search for Related Content PubMed PubMed Citation Articles by Saunders, J. A. Articles by Gillespie, J. M. Agricola Articles by Saunders, J. A. Articles by Gillespie, J. M.

Articles

Localization and Substrate Specificity of Glycosidases in Vacuoles of Nicotiana rustica

Tobacco Laboratory, Plant Genetics and Germplasm Institute, Beltsville, Maryland 20705, Beltsville Agricultural Research Center, United States Department of Agriculture, Beltsville, Maryland 20705

Vacuoles isolated from Nicotiana rustica var brasilia have been shown to contain significant levels of glycosidase activity when assayed using p-nitrophenyl-glycosides as substrates. The substrate specificity for the glycosidases in the vacuolar fraction closely paralleled that found in the protoplasts, and the leaf tissue from which the vacuoles were isolated. The substrate specificity of the vacuolar enzyme(s) was different from glycosidic activity found in the commercial digestive enzyme preparations used to isolate the protoplasts from leaf tissue. It was demonstrated that 70 to 90% of the glycosidases that were found in the protoplasts appeared to be localized within the vacuole, when the p-nitrophenyl substrates - and -;D-galactose, -D-glucose, and -D-mannose were used. Neither the vacuolar nor the protoplast enzymes were active towards the naturally occurring phenolic glycoside, rutin. -Mannosidase appears to be a valuable marker enzyme for vacuoles isolated from mesophyll leaf cells of tobacco.