2bhz: Difference between revisions

Trehalose (alpha-D-glucopyranosyl-1,1-alpha-D-glucopyranose) is a, non-reducing diglucoside found in various organisms that serves as a, carbohydrate reserve and as an agent that protects against a variety of, physical and chemical stresses. Deinococcus radiodurans possesses an, alternative biosynthesis pathway for the synthesis of trehalose from, maltooligosaccharides. This reaction is mediated by two enzymes:, maltooligosyltrehalose synthase (MTSase) and maltooligosyltrehalose, trehalohydrolase (MTHase). Here, we present the 1.1A resolution crystal, structure of MTHase. It consists of three major domains: two beta-sheet, domains and a conserved glycosidase (beta/alpha)8 barrel catalytic domain., Three subdomains consisting of short insertions were identified within the, catalytic domain. Subsequently, structures of MTHase in complex with, maltose and trehalose were obtained at 1.2 A and 1.5 A resolution, respectively. These structures reveal the importance of the three inserted, subdomains in providing the key residues required for substrate, recognition. Trehalose is recognised specifically in the +1 and +2 binding, subsites by an extensive hydrogen-bonding network and a strong hydrophobic, stacking interaction in between two aromatic residues. Moreover, upon, binding to maltose, which mimics the substrate sugar chain, a major, concerted conformational change traps the sugar chain in the active site., The presence of magnesium in the active site of the MTHase-maltose complex, suggests that MTHase activity may be regulated by divalent cations.

2BHZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Deinococcus_radiodurans Deinococcus radiodurans] with MAL, MG, BME and TRS as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alpha-amylase Alpha-amylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.1 3.2.1.1] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2BHZ OCA].  

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