Characterization of recombinant human serum albumin using matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Chromatographically purified recombinant human serum albumin (rHSA), produced in genetically transformed yeast cells, was characterized using matrix-assisted laser desorption ionization time-of-flight (MALDI–TOF) MS techniques. The molecular mass of the intact protein was determined to be 66 671, in good agreement with that of purified HSA which was used as a standard. The identity of rHSA to its natural counterpart was established with high precision using peptide mass fingerprinting of tryptic peptides. Partial amino acid sequence data for rHSA were obtained using Ettan™CAF™ MALDI Sequencing Kit and post-source decay on the tryptic peptides. The results achieved provide strong evidence that MALDI–TOF-MS is an important analytical technique for characterising gene products and for establishing the identity and bio-compatibility of recombinant proteins relative to their natural counterparts.