# Quantifying venom in African snakes: Insights into protein content, yield and body size associations

## TL;DR

This study compares methods to measure protein in African snake venoms and finds that Elapidae snakes have higher protein concentrations than Viperidae.

## Contribution

The study identifies the BCA assay as the most accurate method for quantifying African snake venom proteins and reveals higher concentrations in Elapidae compared to Viperidae.

## Key findings

- BCA assay was the most accurate for quantifying venom proteins.
- Elapidae venoms had significantly higher protein concentrations than Viperidae venoms.
- Venom protein concentrations varied more between Elapidae species than within the same genus.

## Abstract

Snake venoms are complex mixtures primarily composed of toxic proteins used during prey capture and defence. There is limited knowledge concerning the protein concentration of snake venom and the biases of different protein determination methods. Here, we assess the ability of the Qubit protein assay, bicinchoninic acid (BCA) assay, Bradford assay and NanoDrop spectrometry (A280 with a mass extinction coefficient of one) to accurately quantify protein concentrations of toxins isolated from venom, including three-finger toxins and phospholipase A2. The Bradford assays severely underestimated three-finger toxin concentrations and NanoDrop spectrometry overestimated phospholipase A2 concentrations, whilst the BCA assay was the most accurate. Venom from six major African venomous snake genera was also assessed: coral cobras (Aspidelaps spp.); mambas (Dendroaspis spp.); cobras (Naja spp.); bush vipers (Atheris sp.); adders (Bitis spp.); and saw-scaled vipers (Echis sp.). Protein concentration results were inconsistent between methods. Protein concentrations were found to be lowest for Bitis spp. venom and highest for Naja spp. venom and did not vary between species of the same genus. However, in general, Elapidae species had venoms with significantly higher protein concentrations than Viperidae species. Moreover, there was greater variability between Elapidae species. We also determined wet venom yields and used this to provide a tentative estimate of the total protein quantity that may be injected during a snake bite. We found snake weight and length influenced wet venom yield for the Atheris squamigera but not for Bitis arietans and Echis romani. Our results aim to improve our understanding of the physical properties of snake venom.

Image 1

•Assessment of the accuracy of protein assays and standards for snake venom.•The Bradford assay is inaccurate for determining protein concentration in Elapidae.•The BCA assay with BSA standard is an accurate method for African snake venoms.•African Elapidae have higher venom protein concentrations than Viperidae.

Assessment of the accuracy of protein assays and standards for snake venom.

The Bradford assay is inaccurate for determining protein concentration in Elapidae.

The BCA assay with BSA standard is an accurate method for African snake venoms.

African Elapidae have higher venom protein concentrations than Viperidae.