Fluorometric assay using naphthylamide substrates for assessing novel venom peptidase activities

Area of Science:

• Biochemistry
• Toxicology
• Envenomation Studies

Background:

• Peptidases play crucial roles in venom function and evolution.
• Understanding venom composition aids in developing antivenoms and studying biological processes.

Purpose of the Study:

• To investigate the feasibility of using fluorometry to detect peptidase activities in various venoms.
• To characterize and compare the distribution of specific peptidase activities across different snake, scorpion, and spider venoms.

Main Methods:

• Fluorometric analysis using naphthylamine derivatives to detect peptidase activities.
• Assay of neutral aminopeptidase (APN), prolyl-dipeptidyl aminopeptidase IV (DPP IV), basic aminopeptidase (APB), and acid aminopeptidase (APA) activities.
• Comparative analysis of peptidase profiles in venoms from Bothrops, Crotalus, Bitis, Tityus, Phoneutria, and Loxosceles species.

Main Results:

• All examined snake venoms exhibited APN and DPP IV activities, with highest levels in B. alternatus.
• B. arietans venom showed distinct high levels of APA and APB activities, differentiating it from other Brazilian snake venoms.
• Arthropod venoms generally displayed lower peptidase activities, with P. nigriventer's APB activity being an exception. Pyroglutamate aminopeptidase was undetectable in all venoms; T. serrulatus venom showed no detectable peptidase activity.

Conclusions:

• Fluorometry is a feasible method for revealing peptidase activities in venoms.
• Distinct peptidase profiles, particularly APN, DPP IV, APA, and APB activities, highlight evolutionary divergence in venom composition and function.
• The findings provide a basis for further research into venom biochemistry and the specific roles of peptidases in envenomation.