Acid proteases from sábalo stomach mucosa were recovered using salting-out procedure. This single step produced an enzyme extract purified 1.8-fold over the crude extract with a recovery of 45.1% of its initial proteolytic activity. Sábalo proteases exhibited the highest activity at 45 °C-pH 2.0, showed pH stability between 2.0 and 5.0 and retained more than 70% of its activity after incubation at pH 7.0 for 2 h. Fish extract was unstable at temperatures greater than 45 °C. Its activity was inhibited by pepstatin A but not by PMSF, while EDTA and SDS showed partial inhibitory effects. Presence of CaCl2 and MgCl2 increased the proteolytic activity, while increasing concentrations of NaCl strongly decreased it. In addition, compared to the acid extraction method, the use of sábalo enzymatic extract increased 1.7 times the yield of collagen extraction.

The complete knowledge of the toxins that make up venoms is the base for the treatment of snake accidents victims and the selection of specimens for the preparation of venom pools for antivenom production. In this work, we used a fast and direct venomics approach to identify the toxin families in the C.d. terrificus venom, a Southern American Neotropical rattlesnake. The RP-HPLC separation profile of pooled venom from adult specimens followed by mass spectrometry analysis revealed that C.d. terrificus’ venom proteome is composed of 12 protein families, which are unevenly distributed in the venom, e.g., there are few major proteins in the venom's composition phospholipase A2, serine proteinase, crotamine and L-amino acid oxidase. At the same time, the proteome analysis revealed a small set of proteins with low quantity (less than 1.5%), both enzymes (metaloprotease, phospholipase B and 5′-nucleotidase) and proteins (Bradykinin potentiating and C-type natriuretic peptides, C-type lectin convulxin and nerve growth factor). To sum up, this research is the first venomic report of C.d.terrificus venom from Argentina. This proved to be crotamine positive venom that has a lower metalloprotease content than C.d. terrificus venoms from other regions. This information could be used in the discovery of future pharmacological agents or targets in antivenom therapy.