Pehr Victor Edman The Solitary Genius

BIRGER BLOMB√ĄCK

Karolinska Institutet, Fogdevreten 2A, Stockholm, SE-171 77, Sweden

One of the main problems in protein chemistry half a century ago was how to efficiently elucidate the sequence of amino acids in proteins. With laborious methods, only small protein structures had so far been resolved. For insulin, the most famous example, the sequence of its 51 amino acid residues took a decade to unravel. Entertaining the thought of establishing the amino acid sequences for protein molecules with hundreds or even thousands of amino acids was, in general, considered impossible, unrealistic, or meant for a far distant future. Still, there was a general agreement in the biosciences that this information was fundamental to the understanding of various life processes and evolutionary aspects. Then came, what I would call, the Edman revolution.1

1In the 1960s I applied for an appointment as professor at a University in Sweden. Among the credentials I mentioned was my intention to determine the primary structure of fibrinogen, although at the time I only knew short sequences of the N-terminal ends of the three chains, determined by Edman's method, but my belief in the method was steadfast. One of the reviewers admired my resolution but ended with a warning, saying poetically, that the endeavor was like a promise to reveal the ice-hidden land of Antarctica, when only pieces of coastline geography was known. This was how biochemists in those days looked at the prospect of elucidating the primary structure of proteins.

Primary Protein Structure
Pehr Edman in 1960s. To the right is a photo ofPehr at the age 4-5.

In the history of protein chemistry, Pehr Edman will be remembered for his outstanding, painstaking, and, not the least, brilliant work that gave us a novel tool to establish amino acid sequences in proteins; a technique by which amino acids in the protein molecule can be removed and identified -one after the other in a stepwise fashion. The rapid developments in molecular biology during the past 30-40 years would not have been possible without Edman's amino acid sequence method. It is true that today, amino acid sequences of even large proteins are rapidly deduced from the nucleotide sequences of their genes. Still, in order to catch the complementary DNA (cDNA) representing the protein, one needs a partial amino acid sequence, albeit short, and to establish that sequence, one is in need of what is generally known by the eponym Edman degradation. In addition, only direct protein sequencing can provide hard information about the final primary structure of the functioning protein. The chemistry discovered by Edman half a century ago is virtually the only tool we have for this purpose.

Already in the 1940s Pehr Edman set out to solve the problem of rapid and accurate stepwise degradation of protein chains. Throughout his research career, he resisted all temptations to deviate from his set course until he considered the task completed and well done. Rewards for early application of his method to interesting biological and medical problems went to others. At the time of his death he was still engaged in optimizing the method.2

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