Human chromogranin A: Purification and Characterization from Catecholamine storage Vesicles of human Pheochromocytoma

Abstract

Chromogranin A is the quantitatively major soluble protein in catecholamine storage vesicles of the adrenal medulla and sympathetic nerve, and has been a useful index of exocytosis during sympathoadrenal neurosecretion. To probe human catecholamine storage and release, we isolated chromogranin A from chromaffin tissue in human pheochromocytoma, and compared it to chromogranin A isolated from chromaffin tissue in bovine adrenal medulla. The preparation included catecholamine storage vesicle isolation by sucrose gradient centrifugation, removal of Dopamine-β-hydroxylase by affinity chromatography on Concanavalin A-Sepharose, and preparative polyacrylamide gel electrophoresis. Human and bovine chromogranin A displayed considerable interspecies homology. Human chromogranin A is a 68,000 dalton monomeric protein with an unusual amino acid composition (31.53 weight % glutamic acid); an acidic, microheterogeneous isoelectric point (4.57-4.68); a characteristic tryptic digest peptide map; and marked dissimilarity to Dopamine-β-hydroxylase in all properties studied. A new probe of human sympathoadrenal function is available in chromogranin A. © 1984 American Heart Association, Inc.