Pheochromocytomas are tumors of chromaffin neuroendocrine cells, 90% of which occur in the adrenal medulla, the remaining 10% being extra-adrenal. They are characterised by the release of large amounts of the catecholamines adrenaline and noradrenaline [1] and it is these agents that are responsible for the clinical effects on the vascular system: notably anxiety, hypertension and cardiac arrhythmia. However, the presence of a variety of neuropeptides, such as neuropeptide Y, calcitonin gene-related peptide, atrial natriuretic peptide and several others has also been reported. It is likely that these peptides also play a role in the clinical effects of pheochromocytoma on the cardiovascular system [2]. Literature reports on the identification of these peptides are limited and are usually restricted to relatively non-specific radioimmunoassay (RIA) analysis which is useful for the detection of specific known peptides, but not for analysis of novel peptides. Further RIA is not appropriate for obtaining a complete profile of the peptides present in tissue.
Here we report on the mass spectrometric analysis of peptides extracted from pheochromocytoma tissue. Tissue extracts were examined by matrix assisted laser desorption time of flight mass spectrometry (MALDI-TOF) to obtain a profile of multiple peptides extracted from the tissue. Extracted peptides were then fractionated by HPLC and the individual components examined by MALDI-TOF to confirm the number and mass of components. Automated Edman sequencing and LC/MS/MS was carried out to obtain peptide sequences and to match these sequences against protein databases of known proteins.