Calciseptine

Calciseptine (CaS) is a natural neurotoxin isolated from the black mamba Dendroaspis p. polylepis venom. This toxin consists of 60 amino acids with four disulfide bonds. Calciseptine specifically blocks L-Type calcium channels, but not other voltage-dependent Ca²⁺ channels such as N-type and T-type channels.^[1]

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Sequence

Its amino acid sequence is: RICYI HKASL PRATK TCVEN TCYKM FIRTQ REYIS REGCG CPTAM WPYQT ECCKG DRCNK

Isolation

Calciseptine is purified from the venom of black mamba Dendroaspis p. polyepsis via three isolation steps: (1) gel filtration, (2) ion exchange on TSK SP 5PW, and (3) reverse-phase chromatograghy on RP18. It represents 2.8% of the total venom components. ^[2]

Target

Calciseptine blocks L-type Ca²⁺ channels.^[1] As a result, it blocks spontaneous contractions of rat portal vein, contractions of the rat thoracic aorta, uterus and cardiac preparations.

References

1. ^ ^{a b} De Weille, J. R., Schweitz, H., Maes, P., Tartar, A. & Lazdunski, M. Proc. Natl. Acad. Sci. USA 88, 1991 2437-2440.
2. ^ Schweitz, H., Bidard, J.-N. & Lazdunski, M. Toxicon 1990, 18, 847-856.