Biotin (Long Arm) Hydrazide, 50 mg, reacts with aldehyde groups and thus can be used to label carbohydrate groups present in a wide variety of macromolecules. The spacer arm in this product allows optimal accessibility of avidin or streptavidin conjugates to biotin. Incorporation of Biotin (Long Arm) Hydrazide involves a two-step process. First, the saccharide is treated with periodate (not included) that produces aldehyde groups on sugars containing unsubstituted vicinal hydroxyl groups (these are usually present at the non-reducing termini of the oligosaccharide). Next, Biotin (Long Arm) Hydrazide reacts with the aldehyde groups to produce a stable linkage between the saccharide and biotin. This reagent can also be used to couple biotin to carboxyl groups on proteins and other molecules using a carbodiimide coupling method, and to specifically label RNA with biotin at the 3' end.