Nirenberg and Matthaei experiment 2026-10-18
In 1961, Marshall Warren Nirenberg and J. Heinrich Matthaei ground washed Escherichia coli and used centrifugation to prepare a cell-free extract. Reactions at combined ribosomes, soluble components, ATP regeneration and phenylalanine carrying a isotope label, with or without polyuridylic acid, an RNA containing only U. After incubation, trichloroacetic acid precipitation, washing and counting radioactive decay detected label in insoluble material. Added polyuridylic acid strongly increased incorporation; removing ribosomes or ATP regeneration suppressed it. Product characterization supported a phenylalanine polypeptide.[ref]
Nirenberg and Matthaei experiment: preparation, comparison and readout
. Original schematic; readout summarizes qualitative published observations. Details.
The inference connects an imposed RNA template to a specific amino acid product. Yet repeated U alone cannot distinguish one-, two- or three-letter coding units: every possible group still contains only U. Neither triplet length nor the complete genetic code follows.[ref]
The dependence of cell-free protein synthesis in E. coli upon naturally occurring or synthetic polyribonucleotides by Marshall Warren Nirenberg and J. Heinrich Matthaei. p. 1601, Discussion and Note added in proof: coding-unit length not established