Polysaccharide and methods

A molecule comprising a chain of seven or more contiguous units of 4,6-dideoxy-4-formamido-α-mannopyranose, adjacent units being joined by a C1-C2 or a C1-C3 link, the chain having a terminal end and a reducing end, wherein the pyranose ring in the unit of the chain most distal from the reducing end is linked to a cap structure, wherein the cap structure comprises Formula 4:

• wherein R4 is acylamido or a deacylated variant thereof, OH, an alkoxy, an alkyl or a hydroxylated alkyl;
• R5 is an alkyl or a hydroxylated alkyl;
• and
• R6 and R7 are independently selected from —H, —CH3, —CHO, —CH═NR8, —CH═N—NHR8, or —CH2(NH)nR8 where n=1 or 2;
• further wherein R8 is H, a protein or a linker molecule derived from di(N-succinimidyl) glutarate (DSG), 3,4-dibutoxy-3-cyclobutene-1,2-dione, or adipic acid dihydrazide (ADH).

A molecule comprising a chain of seven or more contiguous units of 4,6-dideoxy-4-formamido-α-mannopyranose, adjacent units being joined by a C1-C2 or a C1-C3 link, the chain having a terminal end and a reducing end, wherein the pyranose ring in the unit of the chain most distal from the reducing end is linked to a cap structure, wherein the cap structure consists of Formula 2:

• wherein R2 is selected from OH, an alkoxy or an alkyl;
• R3 is selected from an acylamido or a deacylated variant thereof, OH, an alkoxy, an alkyl or a hydroxylated alkyl;
• R4 is selected from an acylamido or a deacylated variant thereof, OH, an alkoxy, an alkyl or a hydroxylated alkyl, or comprises a modified alkoxy group which comprises an alkyl group conjugated to a linker molecule;
• and
• R5 is an alkyl or a hydroxylated alkyl;
• with the proviso that the cap structure is not a 4,6-dideoxy-4-acylamido-α-D-mannopyranose or a 4,6-dideoxy-4-acylamido-α-D-glucopyranose linked to the remainder of the molecule via its C1.