Abasic site, DNA repair, Fluorescence, Human apurinic/apyrimidinic endonuclease, Stopped-flow enzyme kinetics, RECOGNITION, ACTIVE-SITE, BIOLOGICAL CONSEQUENCES, Human apurinic/apyrimidinic endonudease, CONFORMATIONAL DYNAMICS, 2-AMINOPURINE, DAMAGE, BASE EXCISION-REPAIR, FLUORESCENCE, DIVALENT METAL-IONS, HUMAN AP ENDONUCLEASE, DNA/metabolism, Humans, Substrate Specificity, DNA-(Apurinic or Apyrimidinic Site) Lyase/chemistry, Models, Molecular, DNA Repair, Protein Conformation, Polymorphism, Single Nucleotide, DNA Damage, Kinetics, Mutation