2B5D: Crystal Structure Of The Novel Alpha-Amylase Amyc From Thermotoga Maritima

alpha-Amylases are essential enzymes in alpha-glucan metabolism and catalyse the hydrolysis of long sugar polymers such as amylose and starch. The crystal structure of a previously unidentified amylase (AmyC) from the hyperthermophilic organism Thermotoga maritima was determined at 2.2 Angstroms resolution by means of MAD. AmyC lacks sequence similarity to canonical alpha-amylases, which belong to glycosyl hydrolase families 13, 70 and 77, but exhibits significant similarity to a group of as yet uncharacterized proteins in COG1543 and is related to glycerol hydrolase family 57 (GH-57). AmyC reveals features that are characteristic of alpha-amylases, such as a distorted TIM-barrel structure formed by seven beta-strands and alpha-helices (domain A), and two additional but less well conserved domains. The latter are domain B, which contains three helices inserted in the TIM-barrel after beta-sheet 2, and domain C, a five-helix region at the C-terminus. Interestingly, despite moderate sequence homology, structure comparison revealed significant similarities to a member of GH-57 with known three-dimensional structure, Thermococcus litoralis 4-glucanotransferase, and an even higher similarity to a structure of an enzyme of unknown function from Thermus thermophilus.
PDB ID: 2B5DDownload
MMDB ID: 38021
PDB Deposition Date: 2005/9/28
Updated in MMDB: 2007/11
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 2B5D: tetrameric; determined by author
Molecular Components in 2B5D
Label Count Molecule
Proteins (4 molecules)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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