I am working on membrane proteins and I have tried to:
i.) collect the trypsin digest solution (after in-gel trypsin digest)
directly for Maldi MS analysis with the use of alpha-cyanohydroxycinnamic
acid as the matrix. I found that upon mixing the sample solution and the
matrix - a fine whitish powdery layer is formed together with the crystals.
ii.) do in-gel trypsin digest with the addition of excess buffer so that the
trypsin solution would not dry up overnight in the 37C incubator. The next
morning, there was still trypsin digestion left and I added 0.1%TFA/50%
acetonotrile to the samples followed by sonication. I found the whitish
layer too in these samples after spotting them onto Maldi Sample plate.
Both batches of samples yield no results. I am wondering if anybody has
come across such situations and can give explanation to this.
Thanks in advance!
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