Table 4.
Good substrates, weak substrates, and products of CPZ identified using the tryptic peptide library.
| Ratio CPZ/No Enzyme | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Type | Protein Precursor | Peptide Sequence | Cleaved aa | Z | T | Obs M | Theor M | ppm | 100 nM | 10 nM | 1 nM |
| Good | Thyroglobulin | GQEFTITGQKR | - | 2 | 2 | 1263.66 | 1263.60 | −2 | 0.38 | 1.13 | 0.97 |
| Weak | Thyroglobulin | ALEQATR | - | 2 | 1 | 787.42 | 787.42 | 3 | 0.57 | 1.04 | 1.00 |
| Weak | Thyroglobulin | AVKQFEESQGR | - | 3 | 2 | 1277.64 | 1277.64 | 0 | 0.68 | 0.86 | 0.95 |
| Weak | Bovine serum albumin | KVPQVSTPTLVEVSR | - | 3 | 2 | 1638.93 | 1638.93 | −2 | 0.70 | 0.90 | 0.95 |
| Weak | Bovine serum albumin | KQTALVELLK | - | 3 | 3 | 1141.69 | 1141.71 | −22 | 0.73 | 0.80 | 0.89 |
| Weak | Thyroglobulin | LPESK | - | 2 | 2 | 572.31 | 572.32 | −24 | 0.77 | 0.83 | 0.83 |
| Product | Thyroglobulin | GQEFTITGQK | R | 2 | 2 | 1107.56 | 1107.56 | −4 | 1.52 | 0.78 | 1.04 |
| Product | Thyroglobulin | LF | R | 1 | 1 | 278.16 | 278.15 | 14 | 1.56 | 0.88 | 0.88 |
Good substrates, peptides affected with a decrease ≥60% with the highest concentration of enzyme; weak substrates, peptides affected with a decrease ≥20% and <60% with the highest concentration of enzyme; Products, peptides with an increase >120% with one or more concentrations of enzyme; Cleaved aa, the amino acid cleaved by CPZ to generate the observed peptide; Z, charge; T, number of isotopic tags incorporated into each peptide; Obs M, observed monoisotopic mass; Theor M, theoretical monoisotopic mass; ppm, difference between Obs M and Theor M (in parts per million); Ratio CPZ/no enzyme, the ratio in peak intensity between the sample incubated with enzyme and the sample incubated without enzyme.