Merrifield called this method "solid-phase peptide synthesis." He first used it successfully in 1963 to synthesize a tetrapeptide: a simple chain of four amino acids. Then he prepared a biologically active compound: bradykinin, a nonapeptide hypotensive hormone. Finally, with Arnold Marglin, he synthesized insulin, the smallest polypeptide that qualifies as a protein.

Trained as a biochemist, Merrifield had joined Rockefeller as a postdoctoral fellow in 1949. Many of the problems he worked on during the next decade required the preparation of peptides by tedious classical methods. "They were effective," he says, "but they were laborious and time-consuming. Depending on the size and complexity of the peptide, the process could take months or even years. For a beginner like me it was extremely frustrating."

In 1969, Merrifield and Bernd Gutte synthesized the enzyme ribonuclease A. They chose this enzyme because it is one of the smallest enzymes - 124 amino acids long - and because its properties were well known and largely determined at Rockefeller.

Some 369 chemical reactions and 11,931 mechanical steps later, Merrifield and Gutte had created the chain they sought. They knew its shape would affect how it functioned. The question: Would the synthetic enzyme twist and bend, spontaneously folding into the natural structure? It did, confirming that the primary structure of a protein determines its tertiary structure.

In 1984, Merrifield received the Nobel Prize in chemistry for synthesizing peptides and proteins using a solid matrix. This technology continues to help scientists penetrate and manipulate biological molecules. His work, stated the Royal Swedish Academy of Sciences, "has created completely new possibilities in the field of peptide and protein chemistry ... as well as in the field of nucleic acid chemistry where other researchers have applied Merrifield's ideas."