Purification, Crystallisation and Preliminary X-Ray Studies on Avian Pancreatic Polypeptide

Abstract

A pancreatic polypeptide with some hormonal properties was purified from chicken and turkey pancreas using acid-ethanol extraction, gel filtration and anion-exchange chromatography. The material has been crystallized. The crystals are monoclinic with space group C2. Preliminary isomorphous replacement experiments have so far provided a single-site derivative with Hg(NO3)2. A low-resolution electron density map phased with this derivative using anomalous scattering considered together with Patterson function calculations suggest that the molecules are partly helical and are arranged as a compact dimer about the crystallographic 2-fold axis. The structure and association of these molecules are compared with those of insulin and glucagon, pancreatic protein and polypeptide hormones, respectively, which have been studied in great detail.