Phenetic analysis confirmed that the

BoNT/G complex of proteins shared the most similarity with the/B serotype (Figure 3C-E), as previously reported [10, 23]. To determine the extent of/G’s homology to the/B toxin serotype, we completed an in-depth comparison of six/B subtypes, 22 different accession numbers (Figure 3B, additional files 2). The comparison of individual domains–translocation domain, binding domain NT, binding domain CT, and peptidase–revealed the area of the toxin in which/G shares the greatest (translocation domain) and least (binding domain CT) similarity. Overall, each domain compared, between the two toxins, is greater than 50% similar. This comparison helped to determine which substrate peptide would be optimal to test the activity of/G. FG4592 Although there are no direct indications that sequence similarity would imply overall identical functionality, similar sequences would allow similar crystal structures to form, suggesting similar functionality [24]. It is currently known that both BoNT/B and/G cleave the Synaptobrevin protein;/B cleaves a Gln76-Phe77 bond and/G an Ala81-Ala82 bond five amino acids downstream (Table 1). Because the cleavage

sites of both toxins are relatively near one another–thus the similarity of their binding domain sequences and therefore structures–the same peptide substrate currently used to test/B activity was used to test/G activity Topoisomerase inhibitor [19]. In order to confirm that the commercial BoNT/G complex was active and therefore ever could be considered analogous to the toxin complex found in clinical samples, various dilutions of the commercial toxin were tested using the Endopep-MS method previously described (Figure 6) [19]. In addition to confirming the toxin’s activity, the Endopep-MS experiments indicated a new optimum temperature for/G activity. When reactions were pulsed at 47°C for 10 min, followed by incubation at 42°C for at least eight hours–as opposed to 37°C for a minimum of 17 hr–an increase in activity and in the quality of mass spectra produced was observed. Other serotypes of BoNT (/C and/D) are often associated with botulism in animals,

avians, equines, and bovines, whose body temperatures are higher than those of humans. BoNT/G has yet to be associated with botulism in a particular organism; however, it is possible that/G would be more effective at causing disease in an organism with a higher body temperature than that of humans, similar to BoNT/C and/D. Figure 6 Endopep-MS method confirmation of commercial BoNT/G activity. This is a representative spectrum indicating BoNT/G activity on a specific substrate peptide. 1Intact substrate, 2C-Terminus product mass 1762.9, and 3N-Terminus product mass 2281.8. The sequences are listed in Table 1. *Indicates double charged ion of the intact substrate peptide. Proteomic strategies and analyses used in this study were important to help define the characteristics of proteins associated with the BoNT/G complex.