title: A QM/MM study of Kemptide phosphorylation catalyzed by protein kinase A. The role of Asp166 as a general acid/base catalyst.
abstract: In this work a theoretical study of the γ-phosphoryl group transfer from ATP to Ser17 of the synthetic substrate Kemptide (LRRASLG) in protein kinase A (PKA) has been carried out with a solvated model of the PKA-Mg2ATP-Kemptide system based on the X-ray crystallographic structure. We have used high levels (B3LYP/MM and MP2/MM) of theory to determine the overall reaction paths of the so-called concerted loose mechanism trying to clarify some aspects of that mechanism still under debate. Our calculations demonstrate for the first time in a complete model of the ternary system the viability of the final step of the catalytic mechanism in which the protonation of the phosphokemptide product by Asp166 takes place. Asp166 is a base catalyst that abstracts the HγSer17 of Kemptide thus facilitating the phosphoryl transfer, but it also acts as an acid catalyst by donating the proton just accepted from Ser17 to the O2γATP atom of the phosphoryl group.
authors.affiliation: Institut de Biotecnologia i de Biomedicina and Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain. Angels.Gonzalez@uab.cat.
authors.forename: Ayax
authors.initials: A
authors.lastname: Pérez-Gallegos
authors.forename: Mireia
authors.initials: M
authors.lastname: Garcia-Viloca
authors.forename: Àngels
authors.initials: À
authors.lastname: González-Lafont
authors.forename: José M
authors.initials: JM
authors.lastname: Lluch
mesh_terms: D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry*; D001665:Binding Sites; D055162:Biocatalysis; D020134:Catalytic Domain; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011522:Protons; D011789:Quantum Theory; D013379:Substrate Specificity
chemical_list: D009842:Oligopeptides; D011522:Protons; D001224:Aspartic Acid; C037642:kemptide; D017868:Cyclic AMP-Dependent Protein Kinases