title: Synthesis of ZAlaPheOMe, the precursor of bitter dipeptide in the two-phase ethyl acetate-water system catalysed by thermolysin.
abstract: Enzymatic synthesis of ZAlaPheOMe, the precursor of a bitter dipeptide due to a very strong hydrophobic character of this compound was carried out in a two-liquid-phase ethyl acetate-0.1 moll(-1) Tris-HCl buffer system. The selected system and process conditions (60 degrees C, pH 7.0) ensured high activity and stability of thermolysin, a catalyst of this reaction. Owing to an almost complete extraction of the product to organic phase it was possible to obtain conversion degrees close to unity. The reaction phase was the aqueous phase in which almost whole catalyst mass was accumulated. The amount of protein adsorbed on the interface corresponded to 4-5% of protein dissolved in the aqueous phase. In the description of the enzymatic process rate the equation suitable for the mechanism of tetrahedral complex formation at a random order sequence of substrate bonding was used. The values of constants k=0.222 s(-1), K(mA)=11.5 mmoll(-1), K(mB)=149.3 mmoll(-1) were obtained.
authors.affiliation: Wroclaw University of Technology, Institute of Chemical Engineering, Norwida 4/6, 50-373, Wroclaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Trusek-Holownia
mesh_terms: D000085:Acetates / Q000737:chemistry*; D002384:Catalysis; D003198:Computer Simulation; D004151:Dipeptides / Q000138:chemical synthesis; D004789:Enzyme Activation; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D009842:Oligopeptides / Q000138:chemical synthesis*; D044367:Phase Transition; D011498:Protein Precursors / Q000138:chemical synthesis*; D012996:Solutions; D013499:Surface Properties; D013696:Temperature; D013820:Thermolysin / Q000737:chemistry*
chemical_list: D000085:Acetates; D004151:Dipeptides; D009842:Oligopeptides; D011498:Protein Precursors; D012996:Solutions; C007650:ethyl acetate; D013820:Thermolysin