Cionin: a disulfotyrosyl hybrid of cholecystokinin and gastrin from the neural ganglion of the protochordate Ciona intestinalis

A H Johnsen, J F Rehfeld

Abstract

We have purified an acidic octapeptide from the neural ganglion of the protochordate Ciona intestinalis by a three-step procedure including C18 Sep-Pak fractionation, MonoQ ion-exchange chromatography, and C4 reversed-phase high-performance liquid chromatography. The purification was monitored by an immunoassay specific for the alpha-carboxyamidated COOH terminus common to the mammalian brain-gut hormones, cholecystokinin and gastrin. Automated Edman degradation revealed the sequence Asn-Tyr-Tyr-Gly-Trp-Met-Asp-Phe. In accordance with the high acidity of the peptide, amino acid analysis after cleavage with aminopeptidase M showed that both tyrosyl residues are sulfated. Hence, the structure is Asn-Tyr(SO3)-Tyr(SO3)-Gly-Trp-Met-Asp-Phe-NH2, as also confirmed by identity with the synthetic disulfated peptide in different chromatographic systems. The occurrence of two consecutively sulfated tyrosyl residues after a neutral residue challenges present concepts of consensus sites for tyrosyl sulfation. We conclude that the structure of the peptide, named cionin, suits that of a common ancestor for cholecystokinin and gastrin.

OriginalsprogEngelsk
TidsskriftJournal of Biological Chemistry
Vol/bind265
Udgave nummer6
Sider (fra-til)3054-8
Antal sider5
ISSN0021-9258
StatusUdgivet - 25 feb. 1990
Udgivet eksterntJa

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