title: Comparison of hydrogen determination with X-ray and neutron crystallography in a human aldose reductase-inhibitor complex.
abstract: Protonation states determination by neutron (2.2 A at room temperature) and X-ray (0.66 A at 100 K) crystallographic studies were compared for a medium size enzyme, human aldose reductase (MW=36 kDa), complexed with its NADP+ coenzyme and a selected inhibitor of therapeutic interest. The neutron resolution could be achieved only with the ab initio fully deuterated protein and the subsequent crystallization in D2O of the complex. We used the largest good-quality crystal (1.00x0.67x0.23 mm, i.e. volume of 0.15 mm3) that we were able to grow so far. Both studies enable the determination of protonation states, with a clear advantage for neutrons in the case of less-ordered atoms (B>5 A2). Hydrogen atoms are best determined by a complementary analysis of the Fourier maps obtained from both methods.
authors.affiliation: EMBL, 6 Rue Jules Horowitz, BP 181 Cedex 9, 38042, Grenoble, France.
authors.forename: M P
authors.initials: MP
authors.lastname: Blakeley
authors.forename: A
authors.initials: A
authors.lastname: Mitschler
authors.forename: I
authors.initials: I
authors.lastname: Hazemann
authors.forename: F
authors.initials: F
authors.lastname: Meilleur
authors.forename: D A A
authors.initials: DA
authors.lastname: Myles
authors.forename: A
authors.initials: A
authors.lastname: Podjarny
mesh_terms: D000449:Aldehyde Reductase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D003903:Deuterium / Q000737:chemistry; D006801:Humans; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D009249:NADP / Q000378:metabolism*; D033363:Neutron Diffraction; D011487:Protein Conformation; D011522:Protons
chemical_list: D011522:Protons; D009249:NADP; D006859:Hydrogen; D003903:Deuterium; D000449:Aldehyde Reductase