Biotin-X is an amino-reactive biotinylation reagent with a long spacer arm. The 6-aminocaproic acid spacer arm provides distance between the biotin and the target ligand which helps alleviate steric hindrance. Biotin-X can be used to biotinylate antibodies, proteins, peptides, or amino acids by reacting with primary amines as found in the N-terminus and Lysine side chains. Biotin-X may also be used in the biosynthesis of biotinylated oligosaccharides. Optimal reaction conditions are at a pH of 7-9. Avoid amine-containing buffers, which may compete in the acylation reaction. - Chemical. CAS: 72040-64-3. Formula: C16H27N3O4S. MW: 357.47. Biotin-X is an amino-reactive biotinylation reagent with a long spacer arm. The 6-aminocaproic acid spacer arm provides distance between the biotin and the target ligand which helps alleviate steric hindrance. Biotin-X can be used to biotinylate antibodies, proteins, peptides, or amino acids by reacting with primary amines as found in the N-terminus and Lysine side chains. Biotin-X may also be used in the biosynthesis of biotinylated oligosaccharides. Optimal reaction conditions are at a pH of 7-9. Avoid amine-containing buffers, which may compete in the acylation reaction.