Conformation limited proteolysis in the common neurophysin‐copeptin precursor shown by trypsin‐Sepharose chromatographic proteolysis

Abstract

The guinea pig two‐domain precursor of MSEL‐neurophysin and copeptin has been passed through a trypsin‐Sepharose column in order to mimic the enzyme processing by a membrane‐bound endopeptidase. Only two cleavages were observed located in the inter‐domain sequence (at Arg‐94 and Arg‐98), in contrast to several additional cleavages found when free neurophysin or copeptin is subjected to soluble trypsin. Because the physiological maturation involves a single cleavage at Arg‐94, both local accessibility in the precursor and narrow specificity of the enzyme are implied in the processing.