1pif: Difference between revisions

The crystal structures of porcine pancreatic alpha-amylase isozyme II (PPA, II) in its free form and complexed with the trestatin A derived, pseudo-octasaccharide V-1532 have been determined using Patterson search, techniques at resolutions of 2.3 and 2.2 angstroms, respectively. Seven, rings of the competitive inhibitor V-1532 could be detected in the active, site region as well as two maltose units in secondary binding sites on the, surface. V-1532 occupies the five central sugar binding subsites similar, to the PPA/acarbose structure. A sixth ring exists at the reducing end, connecting two symmetry related PPA molecules. The seventh moiety, a, 6-hydroxymethylconduritol ring, is located at the non-reducing end. The, electron density for this ring is relatively weak, indicating considerable, disorder. This study shows that PPA is able to accommodate more than five, rings in the active site region, but that additional rings would increase, the binding affinity only slightly, which is in accordance with kinetic, experiments. A comparison of the structures of free PPA, PPA/V-1532 and, PPA/Tendamistat shows the characteristic conformational changes that, accompany inhibitor binding and distinguish pseudo-oligosaccharide, inhibitors from proteinaceous inhibitors. Although both classes of, inhibitors block the sugar binding subsites in the active site region, the, extreme specificity and binding affinity of the proteinaceous inhibitors, is probably due to an intricate interaction pattern involving areas, further away from the catalytic center.

1PIF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa] with CA and CL 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 Sites: AS, CA and CL. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1PIF OCA].  

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