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β-1,4-Galactosyltransferase 7 (β4GalT7) is a key enzyme in the biosynthesis of glycosaminoglycan (GAG) chains. Natural and synthetic xylosides can be used to both inhibit and prime GAG synthesis by acting as inhibitors or substrates for β4GalT7. In this report, we exploit hydroxylated oxanes as deoxygenated xyloside analogs to clarify the minimum protein-ligand interactions required for galactosylation and/or inhibition. Enantiomerically pure substances were synthesized using a chiral pool approach whereas the corresponding racemates were obtained from simple starting materials. The results of a β4GalT7 assay show that a single hydroxyl group on an oxane ring is insufficient to induce galactosylation or inhibition, which implies that at least two substituents, one of which being 3-OH, needs to be present.

3′-Phosphoadenosine-5′-phosphosulfate (PAPS) is a key player in the sulfation of biomolecules, but methods for selective measurements are lacking. A liquid chromatography–mass spectrometry (LC–MS) approach for measuring PAPS was developed. A central feature of the method was employing hydrophilic interaction liquid chromatography (HILIC), which is highly suited for separating very polar/charged compounds, and is compatible with electrospray MS. Using simple instrumentation, the analysis time per sample was below 10 min and the method was characterized by easy sample preparation. The method was used to monitor decreasing levels of PAPS as function of sodium chlorate treatment (an inhibitor of PAPS synthesis) in whole-cell lysates as well as Golgi-fractions. The method allowed PAPS to be chromatographically separated from ADP and ATP, which can interfere with measurements if a less resolving LC–MS method is used.