Quantifying protein interactions of pertechnetate: Binding and molecular docking studies

The interaction of pertechnetate (^99mTcO₄^-) with human serum albumin (HSA), lysozyme (Lz), and insulin (Ins) was quantified via precipitation-ultracentrifugation assay and characterized through molecular docking. Experimental results revealed weak, saturable binding with a preserved rank order: HSA > Lz > Ins. The bound fractions were ∼ 22% for HSA, ∼12% for Lz, and ∼ 8-9% for Ins. Molecular docking data showed analogous binding affinities, and identified protein shallow, solvent-exposed regions with polar and cationic patches as the primary interaction sites for pertechnetate. These findings demonstrate that protein composition, particularly albumin levels, directly influences pertechnetate availability and background clearance, providing clinically relevant reference values to optimize tracer timing, enhance image contrast in early scintigraphic frames, and improve diagnostic consistency across diverse patient populations. To the best of our knowledge, this work represents the first quantitative and mechanistic characterization of pertechnetate binding to physiologically relevant proteins, providing clinically applicable reference parameters.