Oxotoxins, or oxytoxins, are a group of
neurotoxins
Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature nerv ...
present in the venom of
lynx spiders belonging to the genus ''
Oxyopes'', hence the name ''oxytoxin''. They are disulfide-rich peptides. Only two types are so far reported from two different species, the larger oxytoxin 1 (OxyTx1) from ''
Oxyopes kitabensis'', and the smaller oxytoxin 2 (OxyTx2) from ''
Oxyopes lineatus''. OxyTx1, the first known oxytoxin, was discovered in 2002. It was found to enhance the lethal efficacy of the spider venom by acting together with
oxyopinins. It is composed of 69
amino acid residue, which are cross-linked by five
disulfide bridges
In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...
. It is a large peptide having a molecular mass of 8059.2
Da; but shows the size of 9,109.4 Da due to the presence of disulfide bridges. It is a potent
insecticide, but non-toxic to mice up to 1 μg/20-g mouse. It acts synergistically with oxyopinins of the same venom to increase the insecticidal effect.
Both OxyTx1 and OxyTx2 were isolated in 2008 from ''O. lineatus''.
Both of these toxins were found to block
voltage-sensitive calcium ion channels. OxyTx2 is made up of 55 amino acid residues and has a molecular mass 6175.2 Da. It is less effective in causing paralysis in ''
Spodoptera litura
''Spodoptera litura'', otherwise known as the tobacco cutworm or cotton leafworm, is a nocturnal moth in the family Noctuidae. ''S. litura'' is a serious polyphagous pest in Asia, Oceania, and the Indian subcontinent that was first described by ...
'' larvae than Oxytx1.
Types
Oxotoxins are classified as follows:
References
External links
Profile at UniProtBioactive Database
{{Toxins
Toxins
Neurotoxins
Spider toxins