Table 2.

Observed masses and assigned dehydration and cysteine modification states for IAA-treated preNsoA1-3 peptides. Shown are calculated theoretical masses of preNsoA1 and preNsoA2-3 peptides with different numbers of dehydrations combined with different numbers of CAM modifications of cysteine residues.

#CAM on Cys	0	1	2	3	4	5	6	7	8
preNsoA1	Number of dehydrations
0	5703.76	5685.75	5667.74	5649.73	5631.72	5613.71	5595.70	5577.69	5559.68
1	5760.78	5742.77	5724.76	5706.75	5688.74	5670.73	5652.72	5634.71	5616.70
2	5817.80	5799.79	5781.78	5763.77	5745.76	5727.75	5709.74	5691.73	5673.72
3	5874.82	5856.81	5838.80	5820.79	5802.78	5784.77	5766.76	5748.75	5730.74
4	5931.84	5913.83	5895.82	5877.81	5859.80	5841.79	5823.78	5805.77	5787.76
5	5988.86	5970.85	5952.84	5934.83	5916.82	5898.81	5880.80	5862.79	5844.78
preNsoA2-3	Number of dehydrations
0	5717.77	5699.76	5681.75	5663.74	5645.73	5627.72	5609.71	5591.70	5573.69
1	5774.79	5756.78	5738.77	5720.76	5702.75	5684.74	5666.73	5648.72	5630.71
2	5831.81	5813.80	5795.79	5777.78	5759.77	5741.76	5723.75	5705.74	5687.73
3	5888.83	5870.82	5852.81	5834.80	5816.79	5798.78	5780.77	5762.76	5744.75
4	5945.85	5927.84	5909.83	5891.82	5873.81	5855.80	5837.79	5819.78	5801.77
5	6002.87	5984.86	5966.85	5948.84	5930.83	5912.82	5894.81	5876.80	5858.79

Bold numbers have been observed in the LC-MS analysis given in Table 1 above. A portion of fully (7- or 8-fold) dehydrated preNosA2-3 with no CAM (underlined italics) is present indicating complete modification including formation of all 5 rings. A series of incomplete dehydrations with increasing number of CAM of preNosA2/3 (all bold) is also present indicating dehydration dependent ring formation.