Protein samples included an E. coli protein lysate (catalog #163-2110), purified bovine serum albumin (BSA) purchased from the National Institute of Standards and Technology (NIST), and bovine carbonic anhydrase (CA) purchased from Sigma- Aldrich. Unless otherwise indicated, samples were prepared in 1x phosphate-buffered saline (PBS). Concentrations of BSA and CA were independently determined using UV spectroscopy and extinction coefficients of 0.667 (at 279 nm) and 1.73 (at 280 nm), respectively, for 1 mg/ml solutions.
The 200 plus LabChip kit, 2100 bioanalyzer, priming station, and 2100 expert software (Rev B.01.02 Si136) were purchased from Agilent Technologies. The Experion Pro260 analysis kit was used for protein analyses with the Experion system, and the protein 200 plus LabChip kit was used with the Agilent 2100 bioanalyzer; samples and microfluidic chips were prepared and loaded according to the protocols described in the instruction manuals for each kit.
Results and Discussion
Molecular Weight Estimation (Sizing)
Knowledge of a proteins MW is fundamental to many applications. For example, in studies of proteolytic or deglycosylation processes, the MW shift of a cleaved protein relative to that of the intact protein is monitored over the course o