High-resolution structure of proteinase K cocrystallized with digalacturonic acid.
Proteinase K, a subtilisin-like fungal protease, was crystallized from a cocktail of small molecules containing digalacturonic acid (DGA). The crystal structure was determined to 1.32 A resolution and refined to an R factor of 0.158. The final model contained, beside the protein, two calcium ions, 379 water molecules, a molecule of DGA and a partially occupied HEPES molecule. The DGA molecule has one sugar moiety disposed exactly on a crystallographic twofold axis; the second ring was not observed. The DGA molecule is bound to two protein molecules across the twofold axis through hydrogen-bonding networks involving Ser150 and water molecules. One of the calcium-ion sites has not been reported previously. This study further illustrates the involvement of small molecules in the crystallization of macromolecules through their ability to form intermolecular lattice interactions.
Larson
Steven B
SB
Department of Molecular Biology and Biochemistry, The University of California, Irvine, 92697-3900, USA.
Day
John S
JS
Nguyen
Chieugiang
C
Cudney
Robert
R
McPherson
Alexander
A
D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D004187:Disaccharides / Q000737:chemistry*; D019286:Endopeptidase K / Q000737:chemistry*; D008958:Models, Molecular; D013400:Sugar Acids / Q000737:chemistry*; D013499:Surface Properties
D004187:Disaccharides; D013400:Sugar Acids; D019286:Endopeptidase K; C090179:digalacturonic acid; D002118:Calcium