Early life Mahlon Bush Hoagland was born in
Boston,
Massachusetts, in 1921 to
Hudson Hoagland and Anna Hoagland. Hudson was an American physiologist who was known for co-founding the Worcester Foundation for Experimental Biology with
Gregory Pincus. Mahlon Hoagland graduated from
The Hill School in 1940 and attended
Williams College, and in 1948 received his M.D. from
Harvard Medical School with intentions of becoming a pediatric surgeon. Hoagland took a research position at
Massachusetts General Hospital in the lab of
Paul Zamecnik, where he researched and detailed the role of
transfer RNA in forming proteins. From 1953 to 1967, Hoagland served as an associate professor of microbiology at Harvard Medical School. In 1970, Hoagland became scientific director of the Worcester Foundation for Experimental Biology, retiring in 1985 after 15 years in the directorship. In the early 1950s, Hoagland and his associates were able to show that
polypeptide synthesis occurs on
ribosomes. They did this by giving a rat injections of radioactive
amino acids, waiting for a defined period of time, extracting the liver, and examining sub-cellular fractions for radioactivity. He found that after longer periods of times (hours, days) radioactively labeled proteins were present in all subcellular fractions. However, if they allowed less time to pass, radioactivity was found in only certain particles, which they deemed the sites of proteins synthesis. These particles were named ribosomes. During their experiments with rat liver cells, Hoagland and Zamecnik noticed that in the presence of
ATP, amino acids associate with heat soluble RNA, which was later named
transfer RNA (tRNA). This amino acid and tRNA complex was later called
aminoacyl-tRNA. Hoagland's major contribution to the laboratory was in his work with amino acid activating enzymes. He discovered that certain enzymes were required to activate amino acids so they could associate with tRNA molecules and eventually be incorporated into new protein molecules. These enzymes were named
aminoacyl tRNA synthetases. Incidentally, this lab's discovery of tRNA supported the theory of
complementarity (molecular biology) proposed by
Watson and
Crick. He was awarded the
Franklin Medal in 1976. Mahlon Hoagland's other work involved the carcinogenic effects of
beryllium, biosynthesis of
coenzyme A, as well as
liver regeneration and control. ==Notes==