Syntheses of two tyrosine-sulphate containing peptides. Leucosulfakinin (LSK)-II and cholecystokinin (CCK)-12, using the 0--(methylsulphinyl)benzyl serine for the selective sulphation of tyrosine
A novel approach for the synthesis of tyrosinesulphate [Tyr(SO3H)]-containing peptides was developed. In this approach, trifluoroacetic acid stable O-p-(methylsulphinyl)-benzyl group was used as a keyprotectinggroup for serine to achieve the selective sulphation of tyrosine.