What causes peak broadening in NMR?
Peak broadening reflects shortened transverse relaxation and chemical exchange processes. When nucleus exchanges between two chemical environments at rate comparable to chemical shift difference, intermediate exchange regime creates coalesced broad lines due to dephasing and uncertainty in transition frequency. In biological NMR, conformational interconversion, ligand association-dissociation, and acid-base proton transfer cause such broadening. Fast exchange narrows averaged signal, slow exchange gives separate sharp peaks. Adjusting temperature, pH, or ligand concentration modulates exchange
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
