Calciseptine

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Calciseptine (CaS) is a natural neurotoxin

Neurotoxin

A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels.Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

 isolated from the black mamba Dendroaspis p. polylepis venom

Venom

Venom is any of a variety of toxins used by certain types of animals. Generally, venom is injected by such means as a bite or a sting.-The distinction between venom and poison:...

. This toxin consists of 60 amino acids with four disulfide bonds. Calciseptine specifically blocks L-Type calcium channel

Calcium channel

A Calcium channel is an ion channel which displays selective permeabiltiy to calcium ions. It is sometimes synonymous as voltage-dependent calcium channel, although there are also ligand-gated calcium channels.-Comparison tables:...

s, but not other voltage

Voltage

Voltage is commonly used as a short name for electrical potential difference. Its corresponding SI unit is the volt...

-dependent Ca²⁺ channels such as N-type and T-type channels.

Sequence

Its amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and one of the twenty R-groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H₂NCHRCOOH, where R is an organic substituent...

 sequence is: RICYIHKASL PRATKTCVEN TCYKMFIRTQ REYISERGCG CPTAMWPYQT ECCKGDRCNK

Isolation

Calciseptine is purified from the venom of black mamba

Black mamba

The Black Mamba , is an elapid snake and is one of Africa's most dangerous and feared snakes. It has a wide range of known locations throughout Africa. The black mamba is found in Somalia, Ethiopia, Kenya, Botswana,Uganda, Zambia, Zimbabwe, Angola, Namibia, Malawi, Mozambique, South Africa and the...

 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.

Target

Calciseptine blocks L-type Ca²⁺ channels.
As a result, it blocks spontaneous contractions of rat

Rat

Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

 portal vein, contractions of the rat thoracic aorta

Thoracic aorta

The thoracic aorta is contained in the posterior mediastinal cavity.It begins at the lower border of the fourth thoracic vertebra where it is continuous with the aortic arch, and ends in front of the lower border of the twelfth thoracic vertebra, at the aortic hiatus in the diaphragm where it...

, uterus

Uterus

The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation. The term uterus is used consistently within the medical and related professions; the Germanic term, womb is more common in...

and cardiac preparations.