Adrenocorticotropic hormone derived peptides

The relationship between the structure of a series of peptides derived from the adrenocorticotropic hormone ACTH, and the behavioural activity in an active avoidance behaviour test, has been studied over the past 10-20 years. The results obtained were quite different from those in which endocrine activity relationships were studied. From the outcome of a quantitative study on the structure--behavioural activity of the ACTH-related peptides, suggestions about the spatial interactions at the receptor site were made. This receptor-bound conformation differed from those suggested by solution experiments or found in crystal structures. 

Several of the small physiologically active peptides now are known to be derived from a single protein precursor synthesized by the pituitary gland (43). As shown in Figure 9, ACTH (adrenocorticotropic hormone), /3-LPH ( -lipotropic hormone), /3-MSH ( -melanocyte-stimulating hormone), /3-endorphin, and enkephalin result from the specific proteolytic cleavage of a precursor protein of approximately 8,000 daltons. 

Mezey E, Kiss JZ, Mueller GP, Eskay R, O Donohue TL, Palkovits M (1985) Distribution of the pro-opiomelanocortin derived peptides, adrenocorticotrope hormone, a-melanocyte-stimulating hormone and P-endorphin (ACTH, a-MSH, P-END) in the rat hypothalamus. Brain Res 525 341-347. 

Corticotropin is a peptide hormone secreted by the adenohypophysis, one of the derivatives of pro-opiomelanocortin (POMC) it acts primarily on the adrenal cortex, stimulating its grovrth and the secretion of corticosteroids. Its production is increased during times of stress. It is also known as adrenocorticotropic hormone, ACTH, corticotrophin, adrenocorticotrophin, and adrenocorticotropin. 

The major opioid peptide derived from POMC is /5-endorphin. In addition to /5-endorphin, the POMC precursor also is processed into the nonopioid peptides adrenocorticotropic hormone (ACTH), melanocyte-stimulating hormone (a-MSH), and /5-lipotropin /5-LPH). Proenkephahn contains multiple copies of met-enkephalin, as well as a single copy of leu-enkephalin. Prodynor-phin contains three peptides of differing lengths that aU begin with the leu-enkephalin sequence dynorphin A, dynorphin B, and neoendorphin (Eigure 21-1). 

---