Family 13 amylase

L. K. Skov, O. Mirza, A. Henriksen, G. P. De Montalk, M. Remaud-Simeon, P. Sarcabal, R. M. Willemot, P. Monsan, and M. Gajhede, Amylosucrase, a glucan-synthesizing enzyme from the alpha-amylase family, J. Biol. Chem., 276 (2001) 25273-25278. 

Several plant defensins have also been found to be inhibitors of various enzymes in plant pests. The plant defensins Slctl, SIo 2, and SIa3 were the first plant defensins where inhibition of a-amylase was shown at low concentration whereas purothionins inhibited a-amylase activity only at high concentrations. Blal and BIa2 isolated from barley are two more representatives of proteinaceous a-amylase inhibitors in the plant defensin family. ... 

A novel 13-membered ring thiocyclitol (214), isolated from Salacia reticulata Wight (family Hippocrateaceae), showed promising a-glucosidase inhibitory activity (IC50 maltase, 0.227 /tM sucrase, 0.186 //M isomaltase, 0.099 however, it did not inhibit a-amylase from porcine pan-... 

Reports of life-threatening pancreatitis have occurred in children and adults on this agent. While rare, elevated serum amylase levels are usually confirmatory. Some have been hemorrhagic and led to a rapid decline after initial symptoms, culminating in death. Cases have occurred both shortly after initiation of VPA, as well as after years of exposure. Therefore, it is important to educate patients and their families about the earliest symptoms, including the following ... 

Other amylases, constituting a large family of enzymes that act on different substrates, arc found in saliva, animal tissues, plants, yeast, and other microorganisms. They lind wide use in the manufacture of glue, starchy syrups, and in various steps in the production of brewery and bakery products. 

Huang, N., Sutliff, T.D., Litts, J.C. Rodriguez, R.L. (1990). Classification and characterization of the rice a-amylase multigene family. Plant Molecular Biology 14, 655-68. 

Khursheed, B. Rogers, J.C. (1988). Barley a-amylase genes. Quantitative comparison of steady-state mRNA levels from individual members of the two different families expressed in aleurone cells. Journal of Biological Chemistry 263, 18953-60. 

Groot PC, Mager WH, Frants RR. Interpretation of polymorphic DNA patterns in the human alpha-amylase multigene family. Genomics 1991 ... 

Gomez, L., Martin, E., Hernandez, D., Sanchez-Monge, R., Barber, D., Del Pozo, V., de Andreas, B., Amentia, A., Lahoz, C., Salcedo, D. 1990. Members of the alpha-amylase inhibitors family from wheat endosperm are major allergens associated with baker s asthma. FEBS Lett 261 85-88. 

A number of starch-converting enzymes belong to a single family termed the a-amylase family or family 13 hydrolases. This group of enzymes shares common characteristics such as an eight-stranded a/p barrel structure, the ability to hydrolyze 1,4-a-D-glucosidic linkages of attached polysaccharides in a-conformation, and conserved amino acid residues in the active sites of the enzymes (van der Maarel et al. 2002). 

Amino acid sequence relationships between that of branching enzyme (BE) and amy-lolytic enzymes, such as a-amylase, pullulanase, glucosyltransferase and cyclodextrin glucanotransferase, especially at those amino acids believed to be contacts between the substrate and the amylase family enzymes, were first reported by Romeo et al.283 Baba et al.284 reported that there was a marked conservation in the amino acid sequence of the four catalytic regions of amylolytic enzymes in maize endosperm BEI. As shown in Table 4.12, four regions that putatively constitute the catalytic... 

Table 4.12 Primary structures of branching enzymes indicating the four most conserved regions of the o-amylase family...

The sequences have been derived from references referred to in the text. Two examples of enzymes from the amylase family are shown for comparison. Over 40 enzymes ranging from amylases, glucosidases, various a-1,6-debranching enzymes, and 4 examples of branching enzymes have been compared by Svensson.286 The invariant amino acid residues believed to be involved in catalysis are in bold letters)... 

As indicated in Table 4.12, four regions which constitute the catalytic regions of amylolytic enzymes are conserved in the starch-branching isoenzymes of maize endosperm, rice seed and potato tuber, and the glycogen-branching enzymes of E. coli.286,281 It would be of interest to know whether the seven highly conserved amino acid residues of the a-amylase family listed in bold letters in Table 4.12 are also functional in branching enzyme catalysis. Further experiments, such as chemical modification and analysis of the three-dimensional structure of the BEs, would be needed to determine the nature of its catalytic residues and mechanism. 

Indeed, the seven highly conserved amino acid residues of the a-amylase family also appear to be functional in branching enzyme catalysis. A series of experiments,288 in which amino acids were replaced by site-directed mutagenesis, suggest that the conserved Asp residues of regions two and four and the Glu residue of region 3 (Table 4.12, in bold letters) are important for BEII catalysis. Their exact functions,... 

Primary, secondary and tertiary structures of amylolytic enzymes from a wide variety of sources and functions (the a-amylases, bacterial cyclomaltodextrin glucanosyltrans-ferases, isoamylases and starch-branching enzymes) have been found to be closely related, and have been placed into the so-called structural a-amylase family.176,177 These enzymes have been studied with regard to the number, structure, organization and function of domains.178... 

Mirkov, T. E, Wahlstrom, J. M., Hagiwara, K., Finardi-Filho, F., Kjemtrup, S., and Chrispeels, M. J. 1994. Evolutionary relationships among proteins in the phytohemaglutinin-arcelin-alpha-amylase inhibitor family of the common bean and its relatives. Plant Mol. Biol. 26, 1103-1113... 

The cereal dual function a-amylase/trypsin inhibitor proteins are cysteine-rich, disulphide-rich, double-headed, 13-16 kDa, dual function inhibitor proteins that inhibit both of the digestion enzymes a-amylase and trypsin [290-325] (Table 11). Thus the Zea (com) member of this family, com Hageman factor inhibitor (CHFI), is a double-headed 14 kDa protein that inhibits a-amylase and the serine proteases trypsin and blood clotting Factor Xlla [323-324] (Table 11). The structures of the bifunctional a-amylase/trypsin inhibitor proteins from Eleusine (ragi) (RBI) [292-295] and Zea (com) (CHFI) [325] have been determined. These proteins are structurally similar to the lipid transfer proteins, being composed of a bundle of 4 a-helices together with a short [3-sheet element connected by loops, the a-amylase- and protease-inhibitory domains being separately located [325]. 

Sorghum biolor (sorghum) (Poaceae) SIa4 (13 kDa 10 Cys), SIa5 (13 kDa 10 Cys) Cereal a-Amylase /Trypsin inhibitor family homologue [307]... 

Some of the eight highly conserved amino-acid residues of the a-amylase family may also be functional in branching enzyme catalysis. Research using... 

Svensson, B. 1994. Protein engineering in the a-amylase family Catalytic mechanism, substrate specificity and stability. Plant Molec. Biol. 25,141-157. 

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