Aryl-glycosidase activities in germinating maize

Soluble protein extracts of germinating maize seedlings exhibited a limited ability to hydrolyze purified xylans, and specific assays were unable to confirm the presence of endo-beta-1,4-xylanase activity. However, extracts contained a variety of aryl-glycosidase activities, including beta-glucosidase, beta-xylosidase, and alpha-L-arabinofuranosidase. These activities peaked in three- to four-day seedlings and were particularly concentrated in shoot and root tissues. Maximal levels of beta-glucosidase were two orders of magnitude greater than those of beta-xylosidase or alpha-L-arabinofuranosidase. Isoelectric focusing gels revealed multiple forms of these enzymes. The principal beta-glucosidase and alpha-L-arabinofuranosidase protein species were clustered at beta 4.8-4.9 and beta 5.8-6.0, respectively. beta-Xylosidase activity appeared to be associated with both of these enzymes, and no evidence was obtained for a distinct beta-xylosidase.