Investigating Cadmium and Calcium Binding to Full-length Human Cardiac Troponin C Using Intrinsic Fluorescence

Abstract

Cadmium (Cd), a prevalent toxic metal, poses significant health risks even at low exposure levels, particularly affecting cognitive development, kidney function, and cardiovascular health. Previous research has indicated that divalent Cd can bind to and potentially displace divalent calcium (Ca) ions from essential binding proteins, disrupting Ca-dependent cellular signaling pathways. However, there are gaps in the literature regarding how this process occurs at a molecular level. This study aims to characterize the binding affinities of Cd to human cardiac troponin C (hcTnC), a key calcium-binding protein involved in heart muscle contraction, using intrinsic fluorescence spectroscopy. The results demonstrate that Cd binds to hcTnC with significantly higher affinity than Ca, with the first Cd ion binding more tightly than the second, unlike the cooperative binding of Ca. The results of this study enhance our understanding of how Cd interacts with proteins at the molecular level and contribute to the broader body of research on toxic metal interactions. Additionally, this study offers valuable information for developing novel methods to remove Cd from individuals exposed to this toxic metal.