Vasopressin chemical properties

The thiol group is found in the structure of some amino acids and is essential for keeping proteins in the proper three-dimensional shape required for their biological function. Thus these functional groups play a central role in the structure and chemical properties of biological molecules. The thiol group of the amino acid cysteine is highlighted in blue in the structure of lysine vasopressin presented above. 

In order to review these putative relationships it is first useful to define a subset of well-characterized hormones and neurotransmitters that have been implicated in behavior. The chemicals selected for discussion here are among those for which a robust relationship with behavior has been proposed, including steroids (estrogens, progestins, androgens and glucocorticoids), proteins (prolactin) and the neuropeptides (oxytocin and vasopressin). All of these chemicals may act as hormones, neurotransmitters and/or neuromodulators. In addition, to understand the action of these hormones, it is helpful to be familiar with some of the more common neurotransmitters (described below). Space does not permit a discussion of the behavioral effects of many additional compounds with endocrine or paracrine properties. 

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