As a postdoctoral student in 1956, I joined the lab of Dr. Gorbind Khorana who had just "accidentally" discovered the first practical method for chemical synthesis of short DNA fragments. Working with Khorana sparked my interest in looking at nucleic acids and nucleotides - the units that make up DNA - in chemical terms. At the time, few understood the potential of this type of chemical synthesis or the critical role it would eventually play in modern genetics.

I'd always had in the back of my mind the idea that one might be able to use chemically synthesised oligonucleotides of defined sequences as probes to either isolate or identify naturally occurring nucleic acids. Site-directed mutagenesis, the technique for which I won the Nobel Prize, makes it possible to replace one nucleotide at a time. Gene sequences can be deliberately altered.

This makes it easier to find out what regulates a gene, what makes it start and stop expressing its protein, what the protein does and which of its amino acids are important. The result is a new understanding of how proteins work, particularly in illnesses that may be genetic, like cancer, or infections, like those caused by bacteria or viruses. This should lead to new medicines and maybe even gene therapy, a way to cure hereditary diseases by specifically correcting mutations in the genetic code.