Hyaluronic acid (HA; supplied as the salt sodium hyaluronate, CAS 9067-32-7) is a linear, non-sulfated glycosaminoglycan built from repeating disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine. It is not a peptide: there is no amino acid backbone and no peptide bond. It appears in peptide catalogs because it is a standard co-formulant and comparator in skin and joint research.
Why molecular weight is the key variable
Native HA in tissue can exceed 1 MDa, and chain length changes the biology rather than just the viscosity. High-molecular-weight HA is generally reported as space-filling, water-binding and anti-inflammatory; low-molecular-weight and oligosaccharide fragments generated by hyaluronidase or oxidative cleavage are reported as pro-inflammatory and pro-angiogenic through CD44 and TLR2/4. A specification that states only "hyaluronic acid" is therefore incomplete for research use — the MW range belongs on the certificate of analysis.
Handling: HA is extremely hygroscopic, dissolves slowly and should be allowed to hydrate without vigorous shearing, and its solutions are viscous enough to affect pipetting accuracy. It is degraded by heat, low pH and free radicals.
Related terms and material
PDRN · molecular weight (Da) · hydrophilic. Reference material: Hyaluronic Acid (5 mg lyophilized or 2 mL 1% solution), cosmetic peptides. Further reading: what is hyaluronic acid.