title: Highly sensitive double-fluorescent dye staining on microchip electrophoresis for analysis of milk proteins.
abstract: We demonstrated a highly sensitive double-fluorescent dye staining in microchip electrophoresis (ME) for analysis of milk proteins. The detection sensitivity of ME was very limited so far and needed improvement. Our staining method consisted of two steps. First, in sample preparation before electrophoresis, protein was covalently bound to an amine-reactive fluorescent dye, Cy5. Then, the Cy5-attached protein was denatured with SDS and was further stained, during electrophoresis, with Agilent fluorescent dye, which was noncovalently attached to hydrophobic regions of the SDS-protein complexes. This double-fluorescent staining enhanced fluorescent intensity and lowered the detection limit to 200 pg of protein. This provided higher sensitivity than silver- or SYPRO Ruby-staining methods, which have previously given the highest sensitivity in protein staining. In addition, we applied our staining method to analysis of milk proteins and achieved their successful detection, whereas it was difficult to analyze them by the unimproved method.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, Japan. okada.hiroki@mopera.net
authors.forename: Hiroki
authors.initials: H
authors.lastname: Okada
authors.forename: Noritada
authors.initials: N
authors.lastname: Kaji
authors.forename: Manabu
authors.initials: M
authors.lastname: Tokeshi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Baba
mesh_terms: D000818:Animals; D002138:Calibration; D002232:Carbocyanines; D046209:Electrophoresis, Microchip; D005456:Fluorescent Dyes; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis* / Q000302:isolation & purification; D011489:Protein Denaturation; D012680:Sensitivity and Specificity; D012967:Sodium Dodecyl Sulfate
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D008894:Milk Proteins; C085321:cyanine dye 5; D012967:Sodium Dodecyl Sulfate