Fmoc-Thr[GalNAc(Ac)3-α-D]-OH (Fmoc-Thr(AcAcNH-α-Gal)-OH)

AZP-531 is an analogue of unacylated ghrelin designed to improve glycaemic control and reduce weight.

The O-glycosidic linkage and the O-acetyl protection in this building block is stable to both piperidine and TFA, making it completely compatible with standard protocols in Fmoc solid phase peptide synthesis. The Tn antigen is a tumor-associated carbohydrate antigen that is not normally expressed in peripheral tissues or blood cells. Expression of this antigen, which is found in a majority of human carcinomas of all types, arises from a blockage in the normal O-glycosylation pathway in which glycans are extended from the common precursor GalNAcα1-O-Ser/Thr (Tn +antigen). This precursor is generated in the Golgi apparatus on newly synthesized glycoproteins by a family of polypeptide α- N-acetylgalactosaminyltransferases (ppGalNAcTs) and then extended to the common core 1 O-glycan Galβ1-3GalNAcα1-OSer/Thr (T antigen) by a single enzyme termed the T-synthase (core 1 β3-galactosyltransferase or C1GalT). Formation of the active form of the T-synthase requires a unique molecular chaperone termed Cosmc, encoded by Cosmc on the X-chromosome[1].

[1]. Ju T, et al. The Cosmc connection to the Tn antigen in cancer. Cancer Biomark. 2014 Jan 1;14(1):63-81.