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Omega-agatoxin-TK Containing D-serine at Position 46, but Not Synthetic omega-[L-Ser46]agatoxin-TK, Exerts Blockade of P-type Calcium Channels in Cerebellar Purkinje Neurons

Omega-agatoxin-TK Containing D-serine at Position 46, but Not Synthetic omega-[L-Ser46]agatoxin-TK, Exerts Blockade of P-type Calcium Channels in Cerebellar Purkinje Neurons

M Kuwada, T Teramoto, K Y Kumagaye, K Nakajima, T Watanabe, T Kawai, Y Kawakami, T Niidome, K Sawada, Y Nishizawa

Mol Pharmacol. 1994 Oct;46(4):587-93.

PMID: 7969037

Abstract:

omega-Agatoxin-TK (omega-Aga-TK), a 48-amino-acid peptide isolated from the venom of the funnel web spider (Agelenopsis aperta), is a selective and potent inhibitor of P-type calcium channels in the nervous system. We have synthesized a peptide that has the amino acid sequence identified for native omega-Aga-TK. The synthetic omega-Aga-TK, however, showed 80-90-fold less potent inhibition of P-type calcium channels, compared with native omega-Aga-TK. Enantiomer analysis of native omega-Aga-TK revealed D-serine at position 46, and synthetic omega-[D-Ser46]Aga-TK had the same potency as native omega-Aga-TK for blocking P-type calcium channels in cultured cerebellar Purkinje neurons. Two peptide fragments of omega-Aga-TK, namely omega-Aga-TK(1-43) and the carboxyl-terminal peptide fragment omega-Aga-TK(44-48), did not produce any significant inhibition of P-type calcium channels or interfere with the blockade of the channels elicited by native omega-Aga-TK. Molecular dynamics calculations showed that the carboxyl-terminal, six-amino-acid peptide of omega-Aga-TK containing D-Ser46 assumes a different conformation than does the peptide containing L-Ser46. These results suggest that the specific conformation of the carboxyl-terminal region of omega-Aga-TK, particularly the configuration of Ser46, together with a beta-sheet structure formed by four disulfide bonds, might be essential for blockade of P-type calcium channels.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP158484425	ω-Agatoxin TK		158484-42-5	Price

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