Abstract: In some embodiments, the present disclosure relates to mutated tRNAs in which the first letter of the anticodon has been substituted to lysidine or agmatidine, and translation systems containing the mutated tRNAs. In a specific embodiment, the present disclosure provides mutated tRNAs capable of selectively translating codon NNA. In another embodiment, the present disclosure provides translation systems capable of translating two or three types of amino acids from a single codon box. In still another embodiment, the present disclosure provides novel methods for synthesizing lysidine diphosphate, agmatidine diphosphate, and derivatives thereof.