title: Protease-catalyzed oligomerization of hydrophobic amino acid ethyl esters in homogeneous reaction media using l-phenylalanine as a model system.
abstract: Enzymatic synthesis of oligopeptides from l-phenylalanine ethyl ester hydrochloride (l-Phe-Et.HCl) and other l-form hydrophobic amino acid ester hydrochlorides in water miscible organic cosolvents was studied. Different proteases, water miscible cosolvents, and effect of different ratios of water miscible cosolvents for protease-catalyzed oligo-phenylalanine [oligo(l-Phe)] were compared. The importance of the use of water miscible cosolvents in transforming reactions from heterogeneous to homogeneous conditions as a potent medium engineering tool for protease-catalyzed oligopeptide synthesis is highlighted. For example, at 0.125 M l-Phe-Et.HCl, 20% (v/v) methanol, 18.6 mg/mL bromelain, in phosphate buffer (0.25M, pH 8), 40 degrees C, for 3 h, oligo(l-Phe) precipitated from the solution to yield 45 +/- 5%, in contrast, in the absence of cosolvent oligo(l-Phe) yield of 29 +/- 5% was obtained. The following reaction conditions were optimized for bromelain catalyzed oligo(l-Phe) synthesis: pH, temperature, substrate, enzyme, and cosolvent concentrations. DP(avg) and chain length distribution in the product peptides were investigated by (1)H NMR and MALDI-TOF.
authors.affiliation: Department of Chemical and Biological Science, NSF I/UCRC for Biocatalysis and Bioprocessing of Macromolecules, Polytechnic Institute of NYU, Six Metrotech Center, Brooklyn, New York 11201, USA.
authors.forename: Kodandaraman
authors.initials: K
authors.lastname: Viswanathan
authors.forename: Ruth
authors.initials: R
authors.lastname: Omorebokhae
authors.forename: Geng
authors.initials: G
authors.lastname: Li
authors.forename: Richard A
authors.initials: RA
authors.lastname: Gross
mesh_terms: D002384:Catalysis; D004952:Esters; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010447:Peptide Hydrolases / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012995:Solubility; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D004952:Esters; D011108:Polymers; D010649:Phenylalanine; D010447:Peptide Hydrolases