A functioning complex between tryptic fragments of cytochrome c. A route to the production of semisynthetic analogues.

We report the discovery of a functioning non-covalent complex between two peptides obtained from a limited tryptic digest of horse heart cytochrome c. We have used the phenomenon to produce three modified versions of the complex. We have replaced lysine-39 semisynthetically with ornithine in the first analogue, with p-fluorophenyl-alanine in the second, and removed it entirely in the third.