Function and Tertiary- and Quaternary-structure of Cyclodextrin-hydrolyzing Enzymes (CDase), a Group of Multisubstrate Specific Enzymes Belonging to the α-Amylase Family

Abstract

Enzymes have a long history of use in industrial applications to produce a broad range of commercial products. Many types of amylases with unique properties have been isolated and characterized for various important applications in the food and starch industry. 1,2) According to the classification system by Henrissat, 3) most of the starch hydrolyzing enzymes belong to the family 13 glycosyl hydrolases (GH13) based on amino acid sequence homology.This group of enzymes have the following features: (i) they hydrolyze glycosidic bonds of various glucans to produce anomeric mono or oligosaccharides (hydrolysis), form 1,4 or 1,6 glycosidic linkages (transglycosylation), or a combination of both activities; (ii) they possess a ( )8 barrel structure containing the catalytic site residues; (iii) they have four highly conserved regions in their primary sequence which contain the amino acids that form the catalytic site. Although these enzymes share many structural and mechanical characteristics, they can be divided into several groups according to substrate specificities, patterns of starch cleavage, transglycosylation or cyclization activities, and structural features.Jespersen et al . 4) used sequence alignments and structure prediction models to forecast the presence of amylase type ( )8 barrel domains and the positions of the strand and helices found in various amylolytic and related enzymes. An evolutionary distance tree constructed from 37 residues representing the four most highly conserved strands of these related enzymes revealed several clusters of enzymes harboring similar reaction specificities. The correlation strongly suggests that the conserved strands may determine substrate and or product specificity.Typical amylases (EC 3.2.1.1; 1,4 D glucan glucanohydrolase) catalyze the hydrolysis of 1,4 glucosidic linkages in starch and give rise to oligosaccharides with certain lengths of glucose as the major product depending on the specific enzyme.

Functional characterization of a special thermophilic multifunctional amylase OPMA-N and its N-terminal domain

“…Thus, the maltogenic amylases constitute a special subfamily of the GH-13 or the a-amylase family together with neopullulanase, cyclomaitodextrinase, and Thermoactinomyces vulgaris R47 amylase II [11,13,14]. These enzymes share similar characteristics of maltogenic amylase [5,[15][16][17]. In general, maltogenic amylases displayed multiple activities.…”

Preliminary Investigation on the Action Modes of an Oligosaccharide-Producing Multifunctional Amylase

“…7) in the presence of substrate. (7), or without OPMA (8). Lanes 9-11 reaction product(s) from maltotriose plus maltose without OPMA (9), with inactive OPMA (10), or active OPMA (11).…”

“…Lanes 3-5 reaction product(s) from maltose with active OPMA (3), inactive OPMA (4), without OPMA (5). Lanes 6-8 reaction product(s) from maltose plus glucose with active OPMA (6), inactive OPMA (7), or without OPMA (8). b HPLC quantitative analysis of products obtained from maltose or maltose plus glucose by OPMA.…”

“…OPMA could form homodimer or homotrimer like MAase [13], CDase [14], or NPase [15]. Dimerization or oligomerization could make them provide simultaneously more than one binding site for donor and acceptor molecules in enzyme active center for transglycosylation or condensation reaction [3,4,8,[15][16][17].…”

“…OPMA catalyzed starch degradation into maltose, maltotriose, and isomaltotriose as well as small amounts of isomaltotetraose, but does not produce glucose. Apparently, OPMA is distinguished from other typical amylases, such as α-amylase or other popular multifunctional amylases such as maltogenic amylase (MAase) [3,4], neopullulanase (NPase) [5,6], or cyclodextrin-hydrolyzing enzymes (CDase) [7,8], not only by its multiple activities, but also by its product composition though they all have the catalytic versatility [9][10][11].…”