Table 2.

Disulfide-linked peptides from RNase A identified in this study. The “No. of matches” column represents the number of unique disulfide-linked peptides that support each disulfide bond. The numbers of spectra matched to each peptide are shown according to trypsin treatment time (3, 6, and 24 hrs). For the Cys⁶⁵–Cys⁷² bond, intra-disulfide linked peptides were observed including missed cleavages in 3-hr and 6-hr trypsin samples.

Disulfide bond	No. of matches	Disulfide–linked peptide	MW calculat ed	No. of spectra
				Tryp 3hrs	Tryp 6hrs	Tryp 24hrs
C26–C84	4	SSTSAASSSNYCNQMMK – CR	2070.8228	2	6	7
		QHMDSSTSAASSSNYCNQMMK – CR	2582.0077	2	2	–
		SSTSAASSSNYCNQMMK – CRETGSSK	2660.0935	1	1	–
		QHMDSSTSAASSSNYCNQMMK – CRETGSSK	3171.2784	1	–	–
C40–C95	9	CKPVNTFVHESLA – YPNCAYK	2299.0765	10	10	11
		CKPVNTFVHESLAD – YPNCAYK	2414.1035	6	8	9
		RCKPVNTFVHESLA – YPNCAYK	2455.1776	6	6	6
		CK – YPNCAYK	1104.4732	2	3	3
		RCK – YPNCAYK	1260.5743	3	3	3
		DRCK – YPNCAYK	1375.6013	4	4	1
		CKPVNTFVHESLA – ETGSSKYPNCAYK	2888.3473	1	–	–
		CK – YPNCAYKTTQANK	1747.8022	–	–	3
		CKPVNTFVHESLA – YPNCAYKTTQANK	2942.4055	–	1	–
C65–C72	4	NVACK – NGQTNCYQSYSTMSIT	2327.9821	8	6	5
		NVACK – NGQTNCYQSYSTMSITD	2443.009	7	7	10
		NVACKNGQTNCYQSYSTMSIT	2309.9715	3	2	–
		NVACKNGQTNCYQSYSTMSITD	2424.9985	1	2	–
C58–C110	9	VQAVCSQK – HIIVACEGNPYVPVHF	2653.3145	21	27	46
		VQAVCSQK – HIIVACEGNPYVPVHFD	2768.3414	23	35	65
		VQAVCSQK – HIIVACEGNPYVPVHFDASV	3025.4789	13	23	42
		VQAVCSQK – TTQANKHIIVACEGNPYVPVHF	3296.6434	7	5	1
		VQAVCSQK – TTQANKHIIVACEGNPYVPVHFD	3411.6703	10	10	2
		DVQAVCSQK – HIIVACEGNPYVPVHFD	2883.3683	1	–	3
		PVNTFVHESLADVQAVCSQK – HIIVACEGNPYVPVHF	3962.9447	9	12	6
		PVNTFVHESLADVQAVCSQK – HIIVACEGNPYVPVHFD	4077.9716	10	10	13
		PVNTFVHESLADVQAVCSQK – HIIVACEGNPYVPVHFDASV	4335.1092	4	9	12