Activities of two de-V-glycosylation enzymes, PNGase (peptide V4(V-acetyl glucosaminyl) asparagine amidase) and ENGase (endo V-acetyl-P-D-glucosaminidase), involved in the re-ease of N-glycans from V-glycoproteins, were montored in several organs of tomato plants (Lycopersicon esculentum, Mill., cv. Dombito) with a fluoeescence-HPLC procedure using a resofurin-labelled N-glycopeptide substrate. PNGase and ENGase activities were detected in every organ assayed but with quantitative differences. The highest activities were found in the youngest parts of the plant, i.e. apical buds, flowers and leaf blades. PNGase activities were consistently higher than ENGase activities (three-fold in average). Both de-V-glycosylation activities were associated with high levels of proteins and protease activities. During fruit growth and ripening, these three parameters decreased notably. The ubiquitous detection of these enzyme activities in the different organs is probably associated with the previously characterized unconjugated N-glycans in tomato. The possible role of PNGase and ENGase degradation products (i.e. unconjugated N-glycans) are discussed in relation with their biological functions in plant development.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.