Larval extracts of the homotetabolous insects (i.e., Neobelleria Bullata-Insecta Diptera), cause paralysis followed by death when injected into adult flesh flies. The reason for causing these lethal effects is because the extracts contain endogenous toxins widely spread over the class of insects. Since their major effect is the paralysis they are called paralysins and are present through all the development stages. Their concentration gradually increases from larvae stage over pupation to late pharate adults indicating that paralysins have an active role in the metamorphosis. The prototype pharmacologically important dipeptide beta-alanine-tyrosine was synthesized and submitted to conformational analysis studies in hydrophilic and amphoteric environments in order to reveal the stereoelectronic properties responsible for its activity.