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PDBsum entry 2ax2

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Lyase PDB id
2ax2
Jmol
Contents
Protein chain
258 a.a.
Metals
_ZN
Waters ×218

References listed in PDB file
Key reference
Title Production and X-Ray crystallographic analysis of fully deuterated human carbonic anhydrase ii.
Authors M.Budayova-Spano, S.Z.Fisher, M.T.Dauvergne, M.Agbandje-Mckenna, D.N.Silverman, D.A.Myles, R.Mckenna.
Ref. Acta Crystallogr Sect F Struct Biol Cryst Commun, 2006, 62, 6-9. [DOI no: 10.1107/S1744309105038248]
PubMed id 16511248
Abstract
Human carbonic anhydrase II (HCA II) is a zinc metalloenzyme that catalyzes the reversible hydration and dehydration of carbon dioxide and bicarbonate, respectively. The rate-limiting step in catalysis is the intramolecular transfer of a proton between the zinc-bound solvent (H2O/OH-) and the proton-shuttling residue His64. This distance (approximately 7.5 A) is spanned by a well defined active-site solvent network stabilized by amino-acid side chains (Tyr7, Asn62, Asn67, Thr199 and Thr200). Despite the availability of high-resolution (approximately 1.0 A) X-ray crystal structures of HCA II, there is currently no definitive information available on the positions and orientations of the H atoms of the solvent network or active-site amino acids and their ionization states. In preparation for neutron diffraction studies to elucidate this hydrogen-bonding network, perdeuterated HCA II has been expressed, purified, crystallized and its X-ray structure determined to 1.5 A resolution. The refined structure is highly isomorphous with hydrogenated HCA II, especially with regard to the active-site architecture and solvent network. This work demonstrates the suitability of these crystals for neutron macromolecular crystallography.
Figure 1.
Active site of (a) hydrogenated and (b) perdeuterated HCA II. Important catalytic side chains in the active sites are shown in yellow ball-and-stick representation and are as labeled. The Zn atom is shown as a black sphere, while solvent molecules are in red. Inferred hydrogen bonds are shown as orange dashed lines. (a) Hydrogenated HCA II (PDB code 1tbt; Fisher et al., 2005[triangle]) and (b) perdeuterated HCA II; the blue electron density shown is a 2F [o] [minus sign] F [c] map contoured at 1.5[sigma]. The figure was generated and rendered using MOLSCRIPT and RASTER3D (Esnouf, 1999[triangle]; Merritt & Bacon, 1997[triangle]). Acta Crystallogr Sect F Struct Biol Cryst Commun. 2006 January 1; 62(Pt 1): 6–9. Published online 2005 December 16. doi: 10.1107/S1744309105038248. Copyright [copyright] International Union of Crystallography 2006
Figure 2.
Optical photograph of a perdeuterated HCA II crystal of approximate dimensions 0.4 x 0.4 x 0.1 mm. Acta Crystallogr Sect F Struct Biol Cryst Commun. 2006 January 1; 62(Pt 1): 6–9. Published online 2005 December 16. doi: 10.1107/S1744309105038248. Copyright [copyright] International Union of Crystallography 2006
The above figures are reprinted from an Open Access publication published by the IUCr: Acta Crystallogr Sect F Struct Biol Cryst Commun (2006, 62, 6-9) copyright 2006.
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