I have analyzed ovalbumin and ovalbumin conjugated to a low mass drug compound by MALDI. The conjugated ovalbumin yields a major broad peak with an average mass of ~48,000. However, the ovalbumin alone produces a broad lump at 27000 and a narrower peak at ~15500. By ESI-MS, the same unconjugated ovalbumin yields masses in the 44,000 range. For the MALDI analysis, I treated both exactly the same: Ziptip for cleanup, sinipinic acid matrix and same MALDI method parameters. This has worked without difficulty for BSA, transferrin and their conjugates.
Has anyone else observed this with ovalbumin? Is there a way around it using MALDI?
Thanks for your time.
Jeanne Corman
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