Skip to main content
. 2008 Aug 16;21(9):1787–1794. doi: 10.1021/tx800144z

Figure 9.

Figure 9

Stability of the diethoxyphosphate adduct of human albumin on Tyr 411. Albumin was treated with CPO to achieve 97% labeling of Tyr 411. Excess CPO was removed by dialysis. The pH of the dialyzed albumin was adjusted to 1.5, 7.4, and 8.3. CPO-albumin samples were stored at 22 and −80 °C. After various times of storage, samples were digested with pepsin and % labeling of Tyr 411 was calculated from cluster areas of labeled and unlabeled peptides in the MALDI-TOF mass spectrometer. CPO-labeled Tyr 411 was stable at pH 1.5 and 7.4 when CPO-albumin was stored at 22 °C (top panel), and it was stable at all pH values when CPO-albumin was stored at −80 °C (bottom panel). Storage of CPO-albumin at pH 8.3 at 22 °C resulted in release of half of the diethoxyphosphate group from Tyr 411 after 3.6 months.