title: Integration of on-line protein digestion, peptide separation, and protein identification using pepsin-coated photopolymerized sol-gel columns and capillary electrophoresis/mass spectrometry.
abstract: A miniaturized pepsin reactor was prepared inside a fused-silica capillary (i.d. 75 microm) by coating a pepsin-containing gel on a photopolymerized porous silica monolith. The pepsin-encapsulated film was prepared by a sol-gel method. The sol-gel reaction was optimized so that the sol solution containing pepsin forms a thin film on the photopolymerized sol-gel (PSG) monolith that was initially fabricated at the inlet of the capillary. Pepsin was encapsulated into the gel matrix without losing its activity. The large surface area of the PSG monolith enabled the immobilized pepsin to achieve a high catalytic turnover rate, and the porous nature of the PSG promotes penetration of large molecular proteins into the column. The immobilized pepsin-digested peptides and proteins, and the resulting mixture of peptide fragments, could be directly separated in the portion of the capillary where no PSG monolith exists. The durability and repeatability of the fabricated pepsin-coated column was tested and found to be satisfactory. An acidic solution consisting of 0.5 M formic acid was used as the running buffer, because it suppresses the adsorption of proteins or peptides on the inner surface of the capillary as well as enables direct connection of the output of the capillary electrophoresis column to a mass spectrometer. The on-line digestion of insulin chain beta and lysozyme provides identification of the proteolytic peptides. Recovery was achieved for 100% of the insulin chain beta amino acid sequence and 73% of the lysozyme amino acid sequence.
authors.affiliation: Department of Analytical Chemistry, School of Pharmaceutical Sciences and COE Program in the 21st Century, University of Shizuoka, 52-1 Yada Shizuoka, Shizuoka 422-8526, Japan. daikato@u-shizuoka-ken.ac.jp
authors.forename: Masaru
authors.initials: M
authors.lastname: Kato
authors.forename: Kumiko
authors.initials: K
authors.lastname: Sakai-Kato
authors.forename: HongMei
authors.initials: H
authors.lastname: Jin
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kubota
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyano
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Toyo'oka
authors.forename: Maria T
authors.initials: MT
authors.lastname: Dulay
authors.forename: Richard N
authors.initials: RN
authors.lastname: Zare
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel / Q000379:methods*; D004063:Digestion; D004151:Dipeptides / Q000378:metabolism; D019075:Electrophoresis, Capillary / Q000379:methods*; D005782:Gels; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000378:metabolism; D008969:Molecular Sequence Data; D009113:Muramidase / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism*; D010449:Peptide Mapping / Q000379:methods*; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification; D010777:Photochemistry; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013499:Surface Properties
chemical_list: D004151:Dipeptides; D005782:Gels; D007328:Insulin; D010455:Peptides; D011506:Proteins; C004980:N-acetylphenylalanyl-3,5-diiodotyrosine; D009113:Muramidase; D010434:Pepsin A