A. Principle
1-Fluoro-2,4-dinitrobenzene (DNFB) reacts with free e-amino groups in proteins, forming DNFB-e-amino lysine which is stable to acid hydrolysis. Test portion is acid hydrolyzed and un available lysine is determined with amino acid analyzer; total lysine is determined on untreated test portion. Available lysine, which was bound by DNFB, is determined by difference.
