title: Glycine peptide bond formation catalyzed by faujasite.
abstract: The catalysis of peptide bond formation between two glycine molecules on H-FAU zeolite was computationally studied by the M08-HX density functional. Two reaction pathways, the concerted and the stepwise mechanism, starting from three differently adsorbed reactants, amino-bound, carboxyl-bound, and hydroxyl-bound, are studied. Adsorption energies, activation energies, and reaction energies, as well as the corresponding intrinsic rate constants were calculated. A comparison of the computed energetics of the various reaction paths for glycine indicates that the catalyzed reaction proceeds preferentially via the concerted reaction mechanism of the hydroxyl-bound configuration. This involves an eight-membered ring of the transition structure instead of the four-membered ring of the others. The step from the amino-bound configuration to glycylglycine is the rate-determining step of the concerted mechanism. It has an estimated activation energy of 51.2 kcal mol(-1). Although the catalytic reaction can also occur via the stepwise reaction mechanism, this path is not favored.
authors.affiliation: Laboratory for Computational and Applied Chemistry, Department of Chemistry, Faculty of Science, Kasetsart University Research and Development Institute, Kasetsart University, Bangkok, Thailand.
authors.forename: Oranit
authors.initials: O
authors.lastname: Phuakkong
authors.forename: Karan
authors.initials: K
authors.lastname: Bobuatong
authors.forename: Piboon
authors.initials: P
authors.lastname: Pantu
authors.forename: Bundet
authors.initials: B
authors.lastname: Boekfa
authors.forename: Michael
authors.initials: M
authors.lastname: Probst
authors.forename: Jumras
authors.initials: J
authors.lastname: Limtrakul
mesh_terms: D002384:Catalysis; D004151:Dipeptides / Q000737:chemistry; D005998:Glycine / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics; D017641:Zeolites / Q000737:chemistry*
chemical_list: D004151:Dipeptides; C539489:faujasite; D017641:Zeolites; D005998:Glycine