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Proteinaceous Inhibitors (proteinaceous + inhibitor)
Selected AbstractsProteinaceous inhibitors of carbohydrate-active enzymes in cereals: implication in agriculture, cereal processing and nutrition,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2006Nathalie Juge Abstract Enzymes that degrade, modify, or create glycosidic bonds are involved in carbohydrate biosynthesis and remodelling. Microbial carbohydrate-active enzymes form the basis of current green technology in the food, feed, starch, paper and pulp industries and the revolution in genomics may offer long-term gains on the quality and quantity of the raw materials. Proteinaceous inhibitors of carbohydrate-active enzymes (,-amylase, limit-dextrinase, polygalacturonase, pectin lyase, pectin methylesterase, invertase and xyloglucan endoglucanase) naturally occur in plants where they are involved in various roles from plant defence to metabolism. Xylanase inhibitors represent the latest addition to this growing family. In this review, we will focus on the inhibitors of carbohydrate-active enzymes present in cereals, mostly represented by ,-amylase and xylanase inhibitors, and summarise the existing knowledge on their structure, function, and implication in cereal processing, agriculture and nutrition. Copyright © 2006 Society of Chemical Industry [source] Functional importance of Asp37 from a family 11 xylanase in the binding to two proteinaceous xylanase inhibitors from wheatFEMS MICROBIOLOGY LETTERS, Issue 1 2004Tariq A. Tahir Abstract Aspergillus niger xylanase is a target enzyme of the two wheat proteinaceous inhibitors, XIP-I and TAXI-I. We previously suggested that the xylanase "thumb" region was XIP-I binding site. Here, we expressed the Asp37Ala mutant in Pichia pastoris and showed that the mutation abolished the enzyme capacity to interact with both inhibitors, suggesting a direct contact at the active site. The mutant pH profile was altered, confirming the key role of Asp37 in determining the pH optima of glycoside hydrolase family 11. The results are consistent with a competitive inhibition mode and underline the strategic importance of Asp37 in the inhibition mechanism. [source] Inhibitors of plant invertases do not affect the structurally related enzymes of fructan metabolismNEW PHYTOLOGIST, Issue 3 2009Ute Kusch Summary ,,Plant fructan active enzymes (FAZYs), including the enzymes involved in inulin metabolism, namely sucrose:sucrose 1-fructosyltransferase (1-SST; EC 2.4.1.99), fructan:fructan 1-fructosyltransferase (1-FFT; EC 2.4.1.100) and fructan 1-exohydrolase (1-FEH; EC 3.2.1.153), are evolutionarily related to acid invertases (AIs), that is, plant cell wall invertase (CWI) and vacuolar invertase (VI). Acid invertases are post-translationally controlled by proteinaceous inhibitors. Whether FAZYs are subject to similar controls is not known. ,,To probe their possible interactions with invertase inhibitors, we transiently expressed chicory (Cichorium intybus) FAZYs, as well as several previously characterized invertase inhibitors from nonfructan species, and the C. intybus cell wall/vacuolar inhibitor of fructosidase (CiC/VIF), a putative invertase inhibitor of a fructan-accumulating plant, in leaves of Nicotiana benthamiana. ,,Leaf extracts containing recombinant, enzymatically active FAZYs were used to explore the interaction with invertase inhibitors. Neither heterologous inhibitors nor CiC/VIF affected FAZY activities. CiC/VIF was confirmed as an AI inhibitor with a stronger effect on CWI than on VI. Its expression in planta was developmentally regulated (high in taproots, and undetectable in leaves and flowers). In agreement with its target specificities, CiC/VIF was associated with the cell wall. ,,It is concluded that subtle structural differences between AIs and FAZYs result in pronounced selectivity of inhibitor action. [source] | ||||||||||