title: Computational Evidence for the Catalytic Mechanism of Tyrosylprotein Sulfotransferases: A Density Functional Theory Investigation.
abstract: In this paper we have examined the mechanism of tyrosine O-sulfonation catalyzed by human TPST-2. Our computations, in agreement with Teramoto's hypothesis, indicate a concerted SN2-like reaction (with an activation barrier of 18.2 kcal mol(-1)) where the tyrosine oxygen is deprotonated by Glu(99) (base catalyst) and simultaneously attacks as a nucleophile the sulfuryl group. For the first time, using a quantum mechanics protocol of alanine scanning, we identified unequivocally the role of the amino acids involved in the catalysis. Arg(78) acts as a shuttle that "assists" the sulfuryl group moving from the 3'-phosphoadenosine-5'-phosphosulfate molecule to threonine and stabilizes the transition state (TS) by electrostatic interactions. The residue Lys(158) keeps close the residues participating in the overall H-bond network, while Ser(285), Thr(81), and Thr(82) stabilize the TS via strong hydrogen interactions and contribute to lower the activation barrier.
authors.affiliation: Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum - Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy.
authors.forename: Tainah Dorina
authors.initials: TD
authors.lastname: Marforio
authors.affiliation: Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum - Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Giacinto
authors.affiliation: Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum - Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bottoni
authors.affiliation: Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum - Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Calvaresi
mesh_terms: D019943:Amino Acid Substitution; D000596:Amino Acids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D011789:Quantum Theory; D055672:Static Electricity; D015238:Sulfotransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D008565:Membrane Proteins; D015238:Sulfotransferases; C114740:TPST2 protein, human