Analytical Ultracentrifugation (AUC) is one of the most precise biophysical techniques used to study macromolecules in their native solution state without the need for chemical labeling or immobilization. The method measures the sedimentation behavior of biomolecules under high centrifugal forces, allowing determination of molecular mass, shape, aggregation state, and intermolecular interactions. Theoretical and Technical Principles AUC experiments are typically conducted at speeds exceeding 60,000 rpm. The technique relies on sedimentation theory, which correlates: Sedimentation coefficient Diffusion coefficient Molecular weight Density and viscosity of the medium Two primary experimental modes are used: Sedimentation Velocity (SV) Sedimentation Equilibrium (SE) Modern AUC systems incorporate optical detection methods such as UV–Vis absorbance and Rayleigh interference optics, enabling real-time monitoring of molecular migration profiles. Advanced computational modeling allows accurate interpretation of macromolecular interactions and heterogeneity. Advanced Applications in Biomarker Research In conditions such as Alzheimer's disease, AUC enables early detection of amyloid-beta aggregation before clinical symptoms appear. In Multiple myeloma, the technique facilitates detailed characterization of abnormal immunoglobulins and monoclonal protein heterogeneity. Additional applications include: Lipoprotein profiling in dyslipidemia Evaluation of therapeutic antibody stability Analysis of circulating immune complexes Challenges High instrument cost Requirement for specialized analytical expertise Long experimental run times in some equilibrium studies Future Perspectives Integration of AUC with: Mass spectrometry Dynamic light scattering Proteomic platforms is expected to enhance molecular-level diagnostics and improve early disease detection strategies. Al-Mustaqbal University Ranked First Among Iraqi Private Universities