A monomeric insulin from the porcupine (Hystrix cristata), an Old World hystricomorph.

The insulins of New World hystricomorph rodents exhibit many novel amino acid changes in primary structure when compared with other mammalian insulins. These changes give rise to unusual properties (low potency, failure to self-associate) not shared by other naturally-occurring insulins. We report here on the primary structure, zinc-binding properties and circular dichroism (CD) of porcupine-insulin (Hystrix cristata), the first Old World hystricomorph insulin to be investigated, and discuss the changes in primary structure of the hormone in relation to its properties. Residue B22 is strongly implicated as being responsible for the unusual properties of porcupine insulin.