Table 1. Crosslinks detected by FINDX within a single protein using the crosslinker BS3.
| Theoretical[MH]+ (Da) | Matched sequences | aCrosslinked amino acid residues | bDistance Cα-Cα (Å)in dimer | cMixed 14N/15N pattern |
| 1272.75 | D154KIK157, T172KVER176 | K155–K173 | 14 (m) | intra |
| 1446.74 | M1QDQR5, T172KVER176 | M1–K173 | Unstr. | inter |
| 1470.89 | I156KAELK161, T172KVER176 | K157–K173 | 18 (m) | intra |
| 1491.67 | M1QDQR5, M1QDQR5 | M1–M1 | Unstr. | - |
| 1515.82 | M1QDQR5, I156KAELK161 | M1–K157 | Unstr. | inter |
| 1712.00 | T172KVER176, K177VIDVQIQ184 | K173–K177 | 12 (m) | intra |
| 1756.93 | M1QDQR5, K177VIDVQIQ184 | M1–K177 | Unstr. | inter |
| 2014.93 | M1QDQR5, E90EEHEIKMR98 | M1–K96 | Unstr. | - |
| 2092.06 | F99DMPGLSKEDVK110, G122EQKK126 | K106–K125 | 13 (m) | - |
| 2095.90 | M1QDQR5, K126EDSDDSWSGR136 | M1–K126 | Unstr. | inter |
| 2141.14 | M1QDQR5, V174ERKVIDVQIQ184 | M1–K177 | Unstr. | intra |
| 2180.04 | M1QDQR5, F99DMPGLSKEDVK110 | M1–K107 | Unstr. | inter |
| 2269.32 | G122EQKK126, A158ELKNGVLFITIPK171 | K125–K161 | 17 (m) | - |
| 2379.21 | G122EQKK126, M97RFDMPGLSKEDVK110 | K125–K106 | 13 (m) | - |
| 2385.17 | M1QDQR5, G19NQGSSVEKRPQQR32 | M1–K27 | Unstr. | inter |
| 2393.24 | A84PWDIKEEEHEIK96, T172KVER176 | K89–K173 | 19 (m) | - |
| 2438.17 | M1QDQR5, A84PWDIKEEEHEIK96 | M1–K89 | Unstr. | - |
| 2440.37 | I111SVEDNVLVIKGEQK125, T172KVER176 | K121–K173 | 28 (x) | inter |
| 2485.30 | M1QDQR5, I111SVEDNVLVIKGEQK125 | M1–K121 | Unstr. | inter |
| 2619.16 | E90EEHEIKMR98, K126EDSDDSWSGR136 | K96–K126 | 11 (d) | - |
| 3042.40 | A84PWDIKEEEHEIK96, K126EDSDDSWSGR136 | K89–K126 | 12 (d) | inter |
| 3089.53 | I111SVEDNVLVIKGEQK125, K126EDSDDSWSGR136 | K121–K126 | 20 (m) | - |
| 3128.58 | E6NSIDVVQQGQQKGNQGSSVEK27, T172KVER176 | K18–K173 | Unstr. | - |
| 3173.51 | M1QDQR5, E6NSIDVVQQGQQKGNQGSSVEK27 | M1–K18 | Unstr. | intra |
Crosslinking was performed with Hsp21, an oligomeric chaperone small heat shock protein [19], at a protein concentration of 50 µM. The data shown in the table is the sum of crosslinks observed in three independent experiments with crosslinker to protein ratios of 1∶1, 10∶1 and 50∶1. Only crosslinks of type 2 are shown (not type 0 and 1). Crosslinks were detected with LC-MALDI-TOFTOF by first using the MS-data for screening in FINDX, and subsequent validation of all crosslinks by MSMS.
Crosslinked lysine residues, designated with amino acid number in sequence (M1 refers to crosslinking with the primary amine in the N-terminal residue, methionine).
The distances between the crosslinked lysine residues in the three-dimensional structure model of Hsp21 [19] are below 20 Å and the cross-links reconcilable with the 3D-structure, m = within monomer, d = within dimer, (x) = one distance was not <20 Å, presumably a crosslink between subunits or oligomers as suggested by its inter-monomeric status in the right-most column, Unstr. = crosslinks involving either M1 or lysine residues in the unstructured N-terminal domain (residues 1–81 in sequence) for which the distance cannot be determined.
intra and inter = intra- and inter-monomeric, - = crosslink not examined by 14N/15N mixed isotope crosslinking as described in Fig. 4.