. Author manuscript; available in PMC: 2014 Oct 6.

Published in final edited form as: J Am Soc Mass Spectrom. 2008 Apr 26;19(7):903–913. doi: 10.1016/j.jasms.2008.04.026

Table 1.

Fragment ions observed in the CID spectrum of SAP corresponding to covalent backbone fragmentation directly from the SAP pentamer. Δm/z corresponds to the difference between the theoretical m/z as determined from the amino acid sequence and the experimentally measured m/z. The measured values for the intact pentamer and the fragment ions for which at least a portion of all 5 subunits are still bound (i.e. Pentamer-covalents) are heavy by ∼2-2.5 m/z due to the presence of solvent adducts.

Fragment Ions Observed by CID	Charge State	Theoretical m/z	Measured m/z	Δ m/z	Cleavage: N-term./C-term. Residue	Complementary Fragment	Complementary Charge State
Pentamer (precursor)	25+	5093.48	5095.95	-2.47	----	----	----
Pentamer	24+	5305.67	5308.14	-2.47	----	----	----
y₄₀-NH₃	3+	1517.45	1517.38	0.07	Leu/Pro	----	----
y₄₀	3+	1523.13	1523.40	-0.27	Leu/Pro	Pentamer-y₄₀	22+
y₂₈	2+	1648.49	1648.46	0.03	Thr/Pro	----	----
y₃₀	2+	1727.56	1727.73	-0.17	Glu/Gly	Penatmer-y₃₀	23+
Pentamer-y₄₀	22+	5580.35	5582.71	-2.36	Leu/Pro	y₄₀	3+
Pentamer-y₄₀	21+	5846.03	5848.62	-2.59	Leu/Pro	y₄₀	3+
Pentamer-(2y₄₀)	19+	6220.96	6223.03	-2.07	Leu/Pro	2y₄₀	3+
Pentamer-(2y₄₀)	18+	6566.52	6568.90	-2.38	Leu/Pro	2y₄₀	3+
Penatmer-y₃₀	23+	5386.17	5387.14	-0.97	Glu/Gly	y₃₀	2+