[17] Protein conjugates of fungal toxins

• Main Authors: Faulstich, H., Fiume, L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1985
• Subjects: Carbonic acid
• Online Access: http://hdl.handle.net/21.11116/0000-0005-9266-3; http://hdl.handle.net/21.11116/0000-0005-92A5-B

The chapter presents the use of toxins for protein coupling with a native carboxylic function, such as β-amanitin (βA) and phallacidin (PC) or chemically modified toxins with carboxylic groups introduced by spacer moieties. Toxin derivatives with functional amino groups can also be coupled to proteins, as proved by the use of αA-N. The toxins and toxin derivatives used in the preparation of protein conjugates are shown in the chapter. Coupling is achieved either by water-soluble carbodiimide or by activation as mixed anhydrides. The chemical procedures and the properties of the conjugates are described. Coupling of amatoxins by carbodiimides, coupling of amatoxins through mixed anhydrides and phallotoxins coupled to proteins are discussed. Carbodiimide coupling may give rise to some unwanted side reactions. For example, urea moieties can be introduced into the protein by an intramolecular acyl transfer in the intermediate O-acylisourea moieties. Activation of carboxylic groups in N-protected α-amino acids, as mixed anhydrides of carbonic acid monoesters is a well-established method of modern peptide chemistry.