Nirenberg and Matthaei experiment
When poly -U experiment of the U.S. biochemist Marshall Nirenberg and his post-doctoral German Heinrich Matthaei in 1961 for the first time was a genetic coding unit are identified - the amino acid phenylalanine could be assigned to the base triplet UUU.
The crucial experimental series in Nirenbergs laboratory at the NIH in Bethesda (Maryland ), which led to the identification of the first code on 27 May 1961 has been designed from 15 May 1961 by Matthaei and carried out so that he has the from knowledge point of view of the title "Father the genetic code, " could be attributed.
The experiment
The so-called " triplet binding assay " by Matthaei Nirenberg and were synthesized fragments with known base sequences short messenger RNA (mRNA). This mixed the two researchers with ribosomes that had been isolated from bacteria. Studies initially showed that ribosomes and mRNA anlagerten together. Then Nirenberg and Matthaei fulfilled all the conditions that are necessary for protein biosynthesis and gave the necessary components into a test tube: Purified ribosomes, a mixture of all 20 amino acids ( from trial to trial was a different amino acid radiolabeled ), and finally a synthetic mRNA with a known base sequence. After all components were assembled and act or could react with each other, the mixture was placed on a filter, the ribosomes, mRNA and newly synthesized protein was holding back, free amino acids but let through (filtrate). Then it was examined whether the radioactive material was in the filtrate, or has just been retained.
Upon addition of a base sequence of the mRNA UUU in this cell -free system for gene expression, and with radiolabeled amino acid serine was no radioactivity bound to the filter (ie, no synthesis of poly- serine ). They were, however, in the next experiment instead of serine, the radiolabeled amino acid phenylalanine added to the radioactive signal was on the filter (ie, synthesis of poly- phenylalanine).
In a further test the system with a mRNA having the base sequence UCU was added. Radioactive serine now found himself on the filter (ie, synthesis of poly -serine ), radioactive phenylalanine, however, in the filtrate (ie, no synthesis of poly- phenylalanine).
From these results, it was concluded that if the triplet base pairing with the amino acid, a protein takes place, and the mRNA is translated.
Marshall Nirenberg was awarded in 1968 along with Gobind Khorana and Robert Holley received the Nobel Prize in Physiology or Medicine.