Recorded: 08 Jun 2006
A fortuitous discovery now appeared in the work with Zamecnik’s group. That was Zamecnik himself and an associate of his discovered that the amino acids, the radioactive amino acids encouraged by the energy from ATP not only were activated as I had discovered but were then subsequently transferred to an RNA molecule. This was a totally mysterious finding because there was no evidence that that RNA that it was attached to—had any role in protein synthesis at all.
It was a small molecular weight, a low molecular weight RNA which we called soluble RNA and of course as we know now became known as transfer RNA and plays the key role in determining the order of amino acids in protein molecules. But at the time we had no awareness of that. We’d discovered that the amino acids bond to this RNA and that I was fortunate enough to have Paul Zamecnik go off and do something else. I did the key experiment based on his discovery that if you take the amino acid label, the amino acid on transfer RNA and incubated it with ribosome’s where proteins are actually made, the radioactive amino acids on transfer RNA were completely transferred over to the ribosome. So suddenly we realized that this RNA was a key intermediate in protein synthesis.
Mahlon Hoagland, a molecular biologist who was one of the discoverer of the transfer ribonucleic acid - tRNA. He received a medical degree from Harvard Medical School in 1948. He served as a doctor during the Second World War. When the War ended he returned to Harvard and became researcher in the Huntington Laboratories at the Massachusetts General Hospital in Boston. He worked in the bacteriology and immunology department of Harvard Medical School from 1952 till 1967.
Working together with Paul Zamecnik and Elizabeth Keller he discovered the initial steps of protein synthesis. Two years later in 1958 Hoagland and Zemecnik discovered tRNA. His main input to the laboratory was in his work with amino acid activating enzymes. He noticed that certain enzymes were required to activate amino acids so they could combine with tRNA molecules and eventually be incorporated into new protein molecules. These enzymes were named aminoacyl tRNA synthetases.
In 1957 Hoagland moved to Cambridge where he worked for a year with Crick at Cambridge University. Working together they tried to explain the genetic code.
He was Associate Professor of Microbiology at Harvard Medical School and in 1967 was appointed professor in the biochemistry department at the Dartmouth Medical School. After 3 years he left Dartmouth and became Director and President of the Worcester Foundation for Experimental Biology in Massachusetts. He retired in 1985.
Mahlon Hoagland was awarded the Franklin Medal for life science. He was a member of the American Academy of Arts and Sciences and the US National Academy of Sciences. He died on September 19, 2009.
More Information: Wikipedia