Amino Acids and Their Biosynthesis, Extraction, Purification, and Refining
摘要
The identification of biosynthetic gene clusters encoding odd combinations of enzymes that generate unidentified natural chemicals is made possible by the genome sequencing of environmental bacteria. We discovered a route in which a short peptide produced by ribosomes acts as a scaffold for chemical peptide elaboration and nonribosomal peptide extension. Adenosine triphosphate and amino acyl-tRNA-dependent chemistry, which is independent of the ribosome, are required for the amino acids to be transported to the carboxyl terminus of the peptide. A tiny molecule formed from an amino acid is produced by the proteolysis, carboxymethylation, and oxidative rearrangement of a terminal cysteine. The end result is shown to be isosteric to glutamate by microcrystal electron diffraction. The biosynthesis of the cytotoxic pyrroloquinoline alkaloids known as ammosamides uses a similar peptide extension. These findings point to a different paradigm for the production of natural compounds generated from amino acids.