Table 2.
Selected cyclization conditions for a number of cystine-knot peptides from various families.
| Peptide | Type | Cyclization reaction; conditions | Yield/Conversion | Reference |
|---|---|---|---|---|
| Variants of cMCoTI | ICK | Immobilized trypsin; 100 mM phosphate buffer, pH = 7.4 | 90–94% a | [44,45] |
| Variants of cMCoTI | ICK | Folding and NCL as one-pot reaction; 50% GSSG (1 mM) in 100 mM carbonate buffer, 50% peptide (3 mM) in acetonitrile | 63–72% b | [45] |
| Variants of cMCoTI | ICK | Hydrazone linkage; multiple reactions from recombinantly produced barnase fusion | 0.5–1 mg/L c | [43] |
| Kalata B1 | CCK | Amide bond; HBTU or BOP, respectively (1–10 eq.), DIEA in DMF | ~25% a | [69] |
| Kalata B1 | CCK | NCL; 100 mM NaH2PO4, TCEP (6 eq.), pH = 7.4, 1 mg/mL peptide | 100% a | [69] |
| hB1 | CCK | NCL; 100 mM NaH2PO4, 6 M GuHCl, thiophenol (100 eq.), pH = 7.5 | 100% a | [55] |
| Cyclic MrIA | Cyclic cono-toxin | NCL; 100 mM Tris-HCl, pH = 7.8, 6 M GuHCl, sodium 2‑sulfonylethane sulfonate (1 mg/mL), anaerobic | 100% a | [98] |
a: HPLC conversion; b: yield according to purified precursor; c: yield of purified cystine-knot peptide is given per liter cell culture.