Deoxyribonucleic acid sodium salt from calf thymus is a high molecular weight, double-stranded DNA preparation used in molecular biology and biochemistry research. It serves as a substrate for enzymes such as DNA polymerases, ligases, restriction endonucleases, and nucleases. Commonly used as a reference standard for nucleic acid quantification by UV spectrophotometry (A₂₆₀). Employed in studies of DNA structure, conformation, viscosity, hydration, and interactions with proteins, ligands, dyes, or intercalators. Applied in gel electrophoresis, filter binding assays, and chromatin reconstitution. Utilized in educational settings for demonstrating DNA properties and enzymatic reactions.