Peptides potential roles

Shah PK, Chyu KY (2005) Apolipoprotein A-I mimetic peptides potential role in atherosclerosis management. Trends Cardiovasc Med 15 291-296... 

The localisation of a particular peptide to a particular brain area and possibly associated with a particular transmitter (e.g. CCK with dopamine in mesolimbic pathways) has often prompted a prediction of function (e.g. CCK may have a role in schizophrenia). Animal studies in which the peptide has been injected into the appropriate brain area or tested on slices taken from the brain area have sometimes been taken to confirm such hypotheses. These approaches have lined up the peptides for a whole range of potential roles, some of which are listed in Table 12.4. Whether these predictions are realities will depend on the availability of chemical agents and their evaluation, not only in animals but also in humans. 

The results of a number of studies demonstrate that the gas nitric oxide (NO) plays a functional role in the central nervous system. This all originated with the discovery that the so-called endothelium-derived relaxing factor (EDRF), found in blood vessels, and thought to be a peptide, was in fact NO. The potential roles of this freely diffusible gas have subsequently been extended to many other tissues and organs but we will concentrate on the possible neuronal roles of what is obviously a novel mediator. There are also suggestions that the closely related carbon monoxide may also have a function in the central nervous system. 

Significant additional interest in the potential role of oxytocin in labour developed from 1993, when it was reported for the first time that oxytocin, which had previously been thought to only be produced in the hypothalamus, may also be synthesised locally in the uterus as indicated by the presence of mRNA encoding for oxytocin [11]. This observation has recently been confirmed by using immunohistochemistry and mass spectrometry to confirm the presence of local oxytocin peptide in the uterus. These studies localised oxytocin to the chorionic trophoblast, decidual stroma and glandular epithelium, and demonstrated that local uterine concentrations of oxytocin increased with the onset of labour [12]. 

It has been clarified that absorbed VY was accumulated in the kidney and aorta in orally administrated SHR, along with the suppression of local ACE activities in both organs (Eig. 2). This finding suggested that both organs must be a targeted tissue for antihypertensive VY. The report that therapeutic ACE inhibitor captopril controlled vessel fimctions also allowed us to consider the potential role of ACE inhibitory small peptides in contracted vessels. 

Another controversial but exciting area of research is the potential role of serotonin in sleep. 5-Hydroxytryptamine may trigger slow-wave sleep (non-REM sleep), whereas the muscarinic AChR and NE are involved in REM sleep (rapid-eye-movement sleep, paradoxical sleep, dream sleep). In addition to the aminergic regulation of sleep, recent research has identified several other presumed sleep factors delta-sleep-inducing peptide, sleep-promoting substance, interleukin-1, and muramyl peptides. 

Sanders, JL, Chattopadhyay, N, Kifor, O, Yamaguchi, T and Brown, EM, 2000, Extracellular calciumsensing receptor (CaR) expression and its potential role in parathyroid hormone-related peptide (PTHrP) secretion in the H-500 rat Ley dig cell model of humoral hypercalcemia of malignancy, Biochem Biophys Res Commun 269 127 132... 

Two peptides that have received attention for their potential role in barrier maintenance are epidermal growth factor (EOF) and transforming growth factor-alpha (TGF-alpha). EGF is secreted in saliva and from duodenal glands, while TGF-alpha is produced by gastric epithelial cells. Both peptides bind to a common receptor and stimulate epithelial ceh proliferation. In the stomach they also enhance mucus secretion and inhibit acid production. 

Lavendustin A and derivatives have been used to study the pathophysiological role of protein kinases. For instance, lavendustin A was used to study the potential role of tyrosine kinases in the regulation of wall stretch-induced atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) secretion. Because lavendustin A is selective for t5n-osine kinases, the data obtained under these conditions showed that this kind of kinase is implicated in regulating cardiac hormone secretion. However, it is still unclear which tyrosine kinase is responsible for wall stretch-induced cardiac hormone secretion [111]. 

The studies by the methods of radiolysis provided a wealth of knowledge about the kinetic and thermodynamic controls of radical reactions, the importance of which is no more questioned. Indeed, it is known that the chemical events initiated by ionizing radiation, are the same as those that take place in normal and deleterious events of every day s life. In this review we focus on some ofthe major knowledge that was acquired by the use of pulse radiolysis and steady-state gamma radiolysis of aqueous solutions of amino acids, peptides and proteins (Inset). The potential role of pulse radiolysis (Chapter 2) for studying biomolecules has been acknowledged rather early. In most cases, pulse radiolysis... 

Phelan, M., Kerins, D. (2011). The potential role of milk-derived peptides in cardiovascular disease. Food Function, 2, 153-167. 

Mulholland, F. (1991) Flavour peptides the potential role of lactococcal peptidases in their production. Food Biotechnol. 19, 685-690. 

---