Autolysis
Low-level digests can be dominated by autolysis peaks. The
peptide masses (neutral, Mr values) for limit digests of bovine and porcine
trypsin are listed below. It is worth screening experimental
data for both species, since the labelling of commercial material
is not always reliable [Vestling,
1990].
The peaks from porcine trypsin at 841.50 and 2210.10 are often used in MALDI
for internal mass calibration. Others peaks which have been observed by MALDI include
514.32, 1044.56, 2282.17, and 2298.17 (2282.17 with oxidised Met)
[Parker, 1998].
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