Disulfide bond rearrangement study using MALDI-TOF TOF mass spectrometry with high and low-energy fragmentation.

Introduction

Ammodytoxins (Atxs) are a group of potent neurotoxins present in the venom of the long-nosed viper (Vipera ammodytes ammodytes). In particular, Atxs (A, B and C) exhibit presynaptic toxicity interfering with the release of acetylcholine from synapses which induces cell damage, apoptosis and ultimately death. Atxs exhibit extensive sequence homology sharing 117 residues in a 122 amino acid sequence. Within the Atxs, there are 7 biologically relevant disulfide bridges between the 14 cysteine residues present. The Atxs sample was cleaved using formic acid for sequence characterisation. Once cleaved, the samples were purified using ZipTip™ with both aqueous and organic fraction elution. The peptide mass fingerprints obtained for the aqueous and organic fractions were different and complementary. These results were compared to the theoretical formic acid peptide fragments for Atxs A, B and C and sequence coverage was calculated to be 95.6% However, it was not possible from these results to unambiguously identify the presence of all the individual Atxs.

November 19, 2013 GMT