Mannanase from Lactuca sativa: Metabolic requirements for production and partial purification

• Published in: Phytochemistry (Oxford) Vol. 28; no. 2; pp. 363 - 369
• Main Authors: Dulson, Jacqueline, Bewley, J.Derek
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 1989; Elsevier
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; biosynthesis; chemical constituents of plants; Compositae; endosperm; endosperm mobilization; enzyme activity; enzyme synthesis and secretion; enzymes; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydrolases; Lactuca sativa; mannanase; protein synthesis; purification; RNA; seeds; mannanase; enzyme synthesis and secretion; Compositae; Lactuca sativa; endosperm mobilization; Purification; Enzyme; Dicotyledones; Angiospermae; Spermatophyta; Biosynthesis; β-D-Mannosidase
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/0031-9422(89)80014-7

Endo- (1→4)-β-mannanase is produced by endosperms isolated from ungerminated Grand Rapids lettuce achenes when they are incubated in a sufficiently large volume of buffer (LV); this production is inhibited if incubation takes place either in a small volume (SV) or with ABA included in the large volume (LV + ABA). This report describes changes in protein and RNA synthesis concominant with mannananase production, the effects of inhibitors specific to these metabolic events on enzyme production, and partial purification of mannase from lettuce endosperms. After 18 hr or more of incubation, protein synthesis is greater in endosperms incubated in a LV than in endosperms incubated in either a SV or a LV + ABA. The peak of protein synthesis in endosperms in a LV precedes that of mannanase activity by ca 4 hr. Mannanase production is cycloheximide-sensitive, indicating that increased mannanase activity is dependent of protein synthesis. RNA synthesis is invariant with incubation conditions. Nevertheless, mannanase production can be reduced, although not prevented, by either actinomycin D or α-amanitin; these results suggest a transcriptional requirement for mannanase production. Partial purification of mannanase was achieved by DEAE-chromatography and affinity chromatography. Mannanase activity in the incubation medium of isolated endosperms can be attributed to two polypeptides of apparent M r of 46 000 which may represent isozymes of the enzyme. These M r values are similar to those reported for mannanases from diverse sources. Mannanase is only a minor product protein synthesis in isolated lettuce endosperms.