Insights into the Hypertensive Effects of Tityus serrulatus Scorpion Venom: Purification of an Angiotensin-Converting Enzyme-Like Peptidase.

Daniela Cajado-Carvalho,Bruno Duzzi,Úrsula Oliveira,Alexandre Kuniyoshi,Inácio Junqueira De Azevedo,Leo Iwai,Fernanda Portaro,Roberto Kodama

doi:10.3390/toxins8120348

Abstract

The number of cases of envenomation by scorpions has grown significantly in Brazil since 2007, with the most severe cases being caused by the Tityus serrulatus scorpion. Although envenomed patients mostly suffer neurotoxic manifestations, other symptoms, such as hypertension, cannot be exclusively attributed to neurotoxins. Omics analyses have detected plentiful amounts of metalloproteases in T. serrulatus venom. However, the roles played by these enzymes in envenomation are still unclear. Endeavoring to investigate the functions of scorpion venom proteases, we describe here for the first time an Angiotensin I-Converting Enzyme-like peptidase (ACE-like) purified from T. serrulatus venom. The crude venom cleaved natural and fluorescent substrates and these activities were inhibited by captopril. Regarding the serum neutralization, the scorpion antivenom was more effective at blocking the ACE-like activity than arachnid antivenom, although neither completely inhibited the venom cleavage action, even at higher doses. ACE-like was purified from the venom after three chromatographic steps and its identity was confirmed by mass spectrometric and transcriptomic analyses. Bioinformatics analysis showed homology between the ACE-like transcript sequences from Tityus spp. and human testis ACE. These findings advance our understanding of T. serrulatus venom components and may improve treatment of envenomation victims, as ACE-like may contribute to envenomation symptoms, especially the resulting hypertension.

Highlights

According to Brazil’s Ministry of Health, since 2007 scorpion stings have been the main form of envenomation by animals in this country
As new substrates and hydrolysis rates were observed for T. serrulatus venom (Tsv) when using the angiotensin I-converting enzyme (ACE) buffer, we evaluated inhibition by captopril, a potent and specific human ACE inhibitor, and by EDTA (Table 2)
Using studies of the transcript sequences in the venom glands of scorpions, we show for the studies of the transcript sequences in the venom glands of Tityus spp. scorpions, we show for first the time the presence of an ACE-like peptidase in the venom of first time the presence of an ACE‐like peptidase in the venom of Tityus serrulatus

Summary

Introduction

According to Brazil’s Ministry of Health, since 2007 scorpion stings have been the main form of envenomation by animals in this country. An epidemiological survey conducted by the Ministry of Health shows that, between 2010 and 2013, cases of scorpion envenomation represent 49% of poisonings by venomous animals in Brazil, surpassing those by snakes (17%) and spiders (18.5%). This scenario is mainly attributed to the proliferation of Tityus serrulatus scorpions, synanthropic animals that reproduce by parthenogenesis [1] and whose potent venom contributes to the occurrence of critical clinical envenomation. Neurotoxins in Tsv cause most of the envenomation symptoms by promoting neurotransmitter release from the autonomic nervous system and the adrenal medulla onto several organs [3]. Metallopeptidases, hyaluronidase, biogenic amines, antimicrobial peptides (AMP), and other oligopeptides are present in Tsv [7,8,9]; the role of these molecules in envenomation is still unclear

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Results

Conclusion