Structure and Possible Catalytic Residues of Taka-Amylase A

Matsuura, Yoshiki; Kusunoki, Masami; Harada, Wakako; Kakudo, Masao

doi:10.1093/oxfordjournals.jbchem.a134659

Cited by 623 publications

(465 citation statements)

References 20 publications

(24 reference statements)

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“…At the opposite end of the active site we observe a phenylalanine in AHA (Phe 223) as well as in mammalian (Buisson et al, 1987;Qian et al, 1993;Larson et al, 1994;Brayer et al, 1995;Ramasubbu et al, 1996), and plant (isozyme 2 from barley malt) (Kadziola, 1993;Kadziola et al, 1994) a-amylases, whereas this phenylalanine has been replaced by a tyrosine in TAKA (Matsuura et al, 1984;Swift et al, 1991) and acid (Boel et al, 1990;Brady et al, 1991) a-amylases. Finally, two consecutive tryptophans (46 and 47) are found next to 50.…”

Section: N Aghujan Et Almentioning

confidence: 86%

Crystal structures of the psychrophilic α‐amylase from Alteromonas haloplanctis in its native form and complexed with an inhibitor

et al. 1998

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Alteromonas haloplanctis is a bacterium that flourishes in Antarctic sea-water and it is considered as an extreme psychrophile. We have determined the crystal structures of the a-amylase (AHA) secreted by this bacterium, in its native state to 2.0 8, resolution as well as in complex with Tris to 1.85 8, resolution. The structure of AHA, which is the first experimentally determined three-dimensional structure of a psychrophilic enzyme, resembles those of other known a-amylases of various origins with a surprisingly greatest similarity to mammalian a-amylases. AHA contains a chloride ion which activates the hydrolytic cleavage of substrate a-1,4-glycosidic bonds. The chloride binding site is situated -5 8, from the active site which is characterized by a triad of acid residues (Asp 174, Glu 200, Asp 264). These are all involved in firm binding of the Tris moiety. A reaction mechanism for substrate hydrolysis is proposed on the basis of the Tris inhibitor binding and the chloride activation. A trio of residues (Ser 303, His 337, Glu 19) having a striking spatial resemblance with serine-protease like catalytic triads was found -22 A from the active site. We found that this triad is equally present in other chloride dependent a-amylases, and suggest that it could be responsible for autoproteolytic events observed in solution for this cold adapted a-amylase.Keywords: allosteric activation; cold adaptation; crystal structure; glycosyl hydrolases; inhibition; psychrophilic a-Amylases a-1,4-glucan-4-glucanohydrolase, EC 3.2.1.1 are endoglucanases widely distributed in bacteria, fungi, animals, and plants. They catalyze the hydrolysis of starch, glycogen, and related polysaccharides by cleaving internal a-1,Cglycosidic bonds. In addition to their biochemical interest, a-amylases have a number of important biotechnological applications in food and starch processing industries (Vihinen & Mantsala, 1989).Alteromonas haloplanctis is a gram negative bacterium collected in Antarctica and secreting a calcium-and chloride-dependent a-amylase. It grows at sub-zero temperatures in its natural environment and can be considered as an extreme psychrophile (Feller et al., 1992). The psychrophilic a-amylase is characterized by a high catalytic efficiency which compensates for the reduction of chemical reaction rates inherent to low temperatures. In addition, all biophysical parameters recorded suggest a flexible conformation of this heat-labile a-amylase. The two crystal structures reported here are the first three-dimensional structures of a psy- chrophilic enzyme; moreover, they provide a number of significant features related to various aspects of biochemistry and microbiology. The structure of A. haloplanctis a-amylase cornplexed with Tris allows to understand the molecular basis of glycosidase inhibition by this cation which is a widely used compound in biochemistry. This bacterial a-amylase requires a chloride ion for its activity, a property previously considered as specific to mammalian a-amylases (Brayer et al., 1995). ...

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Section: N Aghujan Et Almentioning

confidence: 86%

Crystal structures of the psychrophilic α‐amylase from Alteromonas haloplanctis in its native form and complexed with an inhibitor

et al. 1998

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“…2) are even more prominent examples of such subtle sequence adjustment. The aspartate near the C-terminus of b7 is: (i) in GH-H an invariant catalytic site residue [3][4][5][6][7][8][9][10][11]; and (ii) in GH31 an invariant and important residue [23][24][25]. Structurally, however, the two aspartates do not correspond to each other (Fig.…”

Section: Remote Sequence Homologiesmentioning

confidence: 99%

“…The main structural feature is the central catalytic (b/a) 8 -barrel domain (i.e. a TIM-barrel fold), in most cases having a distinct domain (called domain B) protruding from the barrel in the place of loop 3 (b3 fi a3 connection) [11,12]. Family GH77 enzymes contain this (b/a) 8 -barrel, but lack domain C found C-terminal to the barrel in GH13 enzymes (see, for example [13]).…”

Section: Introductionmentioning

confidence: 99%

“…Family GH70, in contrast, is believed to possess a circularly permuted version of the GH13-type (b/a) 8 -barrel [14]. Enzymes of the entire clan GH-H are characterised by several (from 4 to 7) conserved sequence regions [15,16] and a common catalytic machinery involving an aspartate in strand b4, a glutamate in strand b5, and an aspartate after strand b7 that are essential for activity [3][4][5][6][7][8][9][10][11]17]. These three constitute the only invariant residues in GH-H [18], aspartate at the b4-strand acting as catalytic nucleophile and the b5-strand glutamate as general acid/base catalyst [19].…”

Section: Introductionmentioning

confidence: 99%

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A remote but significant sequence homology between glycoside hydrolase clan GH‐H and family GH31

2007

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Although both the a-amylase super-family, i.e. the glycoside hydrolase (GH) clan GH-H (the GH families 13, 70 and 77), and family GH31 share some characteristics, their different catalytic machinery prevents classification of GH31 in clan GH-H. A significant but remote evolutionary relatedness is, however, proposed for clan GH-H with GH31. A sequence alignment, based on the idea that residues equivalent in the primordial catalytic GH-H/GH31 (b/a) 8 -barrel may not be found in the present-day GH-H and GH31 structures at strictly equivalent positions, shows remote sequence homologies covering b3, b4, b7 and b8 of the GH-H and GH31 (b/a) 8 -barrels. Structure comparison of GH13 a-amylase and GH31 a-xylosidase guided alignment of GH-H and GH31 members for construction of evolutionary trees. The closest sequence relationship displayed by GH31 is to GH77 of clan GH-H.

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“…A number of tryptophanyl residues and carboxyl groups involved in substrate binding and catalysis have been identified by chemical modification and sequencing (8,9,42,46). The related enzymes, a-amylase and ct-glucosidase, m adchtlon possess critical histidyl residues (2, 6,11,13,14,19,23,38), but modification of glucoamylase by diethyl pyrocarbonate ( 18,31,35) has only been found to decrease the affinity for soluble starch (18). In the light of the structural and functional similarities recognized recently for different starch-degrading enzymes (9,20,41), the role of histidyl and other side chains was reinvestigated in A. niger glucoamylase.…”

Section: Introductionmentioning

confidence: 99%

Side chain reactivities of glucoamylase G2 from aspergillus niger evaluated by group-specific chemical modifications

Håkansson

Svensson

1989

Carlsberg Res. Commun.

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Treatment ofglucoamylase G2 with large excesses of different group specific reagents resulted in modification of 25% of the histidyl, 15% of the tyrosyl, 20-40% of the arginyl, 30-50% of the lysyl and none of the methionyl residues. The modified groups were not critical since the various derivatives possessed from 50% to 100% residual enzymatic activity and retained the thermostability. Carboxamidomethylation occurred specifically at His254 with essentially no change of the kinetic parameters for hydrolysis of maltose and starch. Removal of the two N-linked sugar units by endoglycosidase H was similarly without effect on activity, thermostability and chemical reactivity of the histidyl residues. H*-titration revealed that glucoamylase G2 carries a lower net charge throughout the pH-range 3-11 than predicted from its amino acid composition.

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Structure and Possible Catalytic Residues of Taka-Amylase A

Cited by 623 publications

References 20 publications

Crystal structures of the psychrophilic α‐amylase from Alteromonas haloplanctis in its native form and complexed with an inhibitor

Crystal structures of the psychrophilic α‐amylase from Alteromonas haloplanctis in its native form and complexed with an inhibitor

A remote but significant sequence homology between glycoside hydrolase clan GH‐H and family GH31

Side chain reactivities of glucoamylase G2 from aspergillus niger evaluated by group-specific chemical modifications

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