Bioactive peptides immune defenses

The discovery of a multitude of naturally occurring, bioactive peptides has generated a rich source of pharmacophores from which medicinal chemists are developing new useful therapeutic drugs. After binding to an enzyme, or a membrane receptor, peptide-based inhibitors, neurotransmitters, immunomodulators, and hormones influence cell-to-cell communications and control a variety of vital functions such as metabolism, immune defense, digestion, respiration, sensitivity to pain, reproduction, and behavior. 

G-protein coupled receptors constitute the largest family of signal transduction membrane proteins. They mediate responses of many bioactive molecules including biogenic amines, amino acids, peptides, lipids, nucleotides and proteins. As a result, GPCRs play a crucial role in many essential physiological processes like neurotransmission, cellular metabolism, secretion, cell growth, immune defense and differentiation. 

Experimental studies have shown that Leucinostatin A may be one of the several potentially toxic peptides produced by Acremonium sp. that contribute to the defense of the host. The host plant is relatively immune to Leucinostatin A, because it has an enzyme which transfers two glycosyl residues to leucinostatin A, thus reducing the peptide s bioactivity. From these results it can also be concluded that glucosylation reactions may play a general role in plant defenses, especially against toxin-mediated disease development [120]. 

---