1ahp

Publication Abstract from PubMed

The crystal structure of E. coli maltodextrin phosphorylase co-crystallized with an oligosaccharide has been solved at 3.0 A resolution, providing the first structure of an oligosaccharide bound at the catalytic site of an alpha-glucan phosphorylase. An induced fit mechanism brings together two domains across the catalytic site tunnel. A stacking interaction between the glucosyl residue and the aromatic group of a tyrosine residue at a sub-site remote (8 A) from the catalytic site provides a key element in substrate recognition; mutation of this residue to Ala decreases the Kcat/Km by 10(4). Extrapolation of the results to substrate binding across the site of attack by phosphorolysis indicates a likely alteration in the glycosidic torsion angles from their preferred values, an alteration that appears to be important for the catalytic mechanism.

Oligosaccharide substrate binding in Escherichia coli maltodextrin phosphorylase.,O'Reilly M, Watson KA, Schinzel R, Palm D, Johnson LN Nat Struct Biol. 1997 May;4(5):405-12. PMID:9145112^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.