Titration of ionizable groups in proteins using multiple neutron data sets from a single crystal: application to the small GTPase Ras.

Autor: Knihtila R; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA., Volmar AY; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA., Meilleur F; Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA., Mattos C; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA.
Jazyk: angličtina
Zdroj: Acta crystallographica. Section F, Structural biology communications [Acta Crystallogr F Struct Biol Commun] 2019 Feb 01; Vol. 75 (Pt 2), pp. 111-115. Date of Electronic Publication: 2019 Jan 23.
DOI: 10.1107/S2053230X18018125
Abstrakt: Neutron protein crystallography (NPC) reveals the three-dimensional structures of proteins, including the positions of H atoms. The technique is particularly suited to elucidate ambiguous catalytic steps in complex biochemical reactions. While NPC uniquely complements biochemical assays and X-ray structural analyses by revealing the protonation states of ionizable groups at and around the active site of enzymes, the technique suffers from a major drawback: large single crystals must be grown to compensate for the relatively low flux of neutron beams. However, in addition to revealing the positions of hydrogens involved in enzyme catalysis, NPC has the advantage over X-ray crystallography that the crystals do not suffer radiation damage. The lack of radiation damage can be exploited to conduct in crystallo parametric studies. Here, the use of a single crystal of the small GTPase Ras to collect three neutron data sets at pD 8.4, 9.0 and 9.4 is reported, enabling an in crystallo titration study using NPC. In addition to revealing the behavior of titratable groups in the active site, the data sets will allow the analysis of allosteric water-mediated communication networks across the molecule, particularly regarding Cys118 and three tyrosine residues central to these networks, Tyr32, Tyr96 and Tyr137, with pK a values expected to be in the range sampled in our experiments.
Databáze: MEDLINE
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