Effect of enzyme inhibitors on profiles of IR-ACTH/beta-endorphin in brain and pituitary.

Processing of pro-opiomelanocortin (POMC) in brain and pituitary results in various proportions of multiple peptides appearing as immunoreactive (IR-) ACTH and IR-beta-endorphin. Because it is desirable that molecular profiles of POMC-related peptides reflect in vivo processing and not isolation artifact, inhibition of proteolytic activity during extraction is critical. Although enzyme inhibitors are frequently used during extraction of POMC-related peptides, their benefit or necessity has not been established. To determine the benefit of using enzyme inhibitors for studying molecular profiles of IR-ACTH and IR-beta-endorphin from rat brain and pituitary, chromatographic profiles were compared to assess the effect of each of several enzyme inhibitors. Results suggested that the enzyme inhibitors studied provided no additional benefit in terms of inhibition of extraction proteolysis over that provided by a strong acid and heat inactivation.