Erythromycin is a broad-spectrum natural antibiotic belonging to the Macrolides. It was first isolated from bacteria of the genus Streptomyces (now renamed Saccharopolyspora).
Erythromycin works by stopping protein synthesis in the process known as peptide elongation by stopping the translocation of the ribosome to read the next triplet codon of the mRNA. This is done by binding to the 50S ribosomal subunit and preventing the release of the empty tRNA occupying the P-site. Since the ribosome is jammed up with failure to release the empty tRNA, the ribosome cannot be moved to read another codon. The result is premature termination of peptide synthesis and creating of flawed proteins than result in cell death.