5mon

Joint X-ray/neutron structure of cationic trypsin in complex with 2-aminopyridine

spinqualitylabelsall models 5mon, resolution 0.94Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5mon is a 1 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 2AP, CA, DOD, SO4 Related: 5mnb, 5mnx Activity: Trypsin, with EC number 3.4.21.4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Hydrogen atoms play a key role in protein-ligand recognition. They determine the quality of established H-bonding networks and define the protonation of bound ligands. Structural visualization of H atoms by X-ray crystallography is rarely possible. We used neutron diffraction to determine the positions of the hydrogen atoms in the ligands aniline and 2-aminopyridine bound to the archetypical serine protease trypsin. The resulting structures show the best resolution so far achieved for proteins larger than 100 residues and allow an accurate description of the protonation states and interactions with nearby water molecules. Despite its low pKa of 4.6 and a large distance of 3.6 A to the charged Asp189 at the bottom of the S1 pocket, the amino group of aniline becomes protonated, whereas in 2-aminopyridine, the pyridine nitrogen picks up the proton although its amino group is 1.6 A closer to Asp189. Therefore, apart from charge-charge distances, tautomer stability is decisive for the resulting binding poses, an aspect that is pivotal for predicting correct binding. Charges Shift Protonation: Neutron Diffraction Reveals that Aniline and 2-Aminopyridine Become Protonated Upon Binding to Trypsin.,Schiebel J, Gaspari R, Sandner A, Ngo K, Gerber HD, Cavalli A, Ostermann A, Heine A, Klebe G Angew Chem Int Ed Engl. 2017 Apr 18;56(17):4887-4890. doi:, 10.1002/anie.201701038. Epub 2017 Mar 28. PMID:28371253 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Trypsin

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