INSECT AND FUNGAL CHITIN SYNTHETASE-ACTIVITY - SPECIFICITY OF LECTINS AS ENHANCERS AND NUCLEOSIDE PEPTIDES AS INHIBITORS

Tribolium castaneum chitin synthetase (CS) activity is stimulated by chitooligosaccharide-binding lectins by up to 2.5-fold in the presence of N-acetyl-d-glucosamine (GlcNAc) and up to 3.5-fold in the absence of GlcNAc. Lectins of particularly high stimulating activity are those obtained from Triticum vulgaris and Phytolacca americana, but not those derived from eight other species with no specificity for GlcNAc. T. castaneum CS is inhibited 50% by 0.2 μM nikkomycin Z (NZ) and the inhibitory effect is not alleviated by stimulating lectins. The CS of Neurospora crassa differs from that of T. castaneum by its lower sensitivity to inhibition by NZ and lesser stimulatory effects of lectins. Apparently the lectins do not act at the active site of Tribolum CS but may instead facilitate the detachment of GlcNAc polymers, thereby enhancing incorporation of label from uridine 5′-diphospho-[3H]GlcNAc. © 1990.