Structural analysis of human proparathyroid hormone by a new microsequencing approach

RECENT evidence indicates that the synthesis of several polypeptide hormones, including parathyroid hormone, involves the production of precursor molecules larger than their corresponding hormones^1-5. The hormones are generated intracellularly by specific enzymatic cleavage. This process may represent an important control mechanism for hormonal synthesis, cellular storage and eventual secretion of the hormone. Thus complete structural characterisation of both precursor and product molecules for further peptide hormones in several species is clearly desirable. The precursor forms are often present in extremely low concentrations in glandular tissue, however, rendering difficult their isolation and sequence analysis by conventional chemical methods.