Gilbert, Walter

(1932– ) US molecular biologist: isolated the first gene repressor.

Gilbert made a remarkable transition: from a basis of physics and mathematics at Harvard and Cambridge and a post at Harvard as a theoretical physicist, he changed in 1960 to biochemistry and molecular biology and became professor of biophysics at Harvard in 1964 and of molecular biology in 1968 and F Jacob (1920–) had proposed in 1961 that gene action is controlled by a ‘repressor substance’ whose function is to ‘turn off’ the gene when it is not needed. In 1966 Gilbert and B Muller-Hill devised and successfully used an ingenious method for isolating one of these hypothetical substances, which are present only in traces in cells. They purified their sample of the lac -repressor (ie the repressor that represses the action of the gene that forms an enzyme that acts on lactose) and showed it to be a protein.

Later he worked on the problem of finding the sequence of bases in DNA and devised an elegant method, broadly similar to but suitable for either single-or double-stranded DNA; the two methods are complementary and each is best suited to particular cases. Gilbert shared a Nobel Prize for chemistry in 1980.