Abstract
NEVER throw away your wide ties, for one day they are certain to come back in style. This is a useful tip in science as well - today's backwater is often tomorrow's hot field, the proteases being a good example. Enzymology began with these digestive enzymes, but by the
1970s they were considered passe. Now they are centre-stage once more, figuring prominently in the design of drugs against AIDS, emphysema, arthritis and hypertension. On page 37 of this issue, a new Achilles' heel is presented for antiviral agents: the three-dimensional structure is described of a viral protease that in effect shoots itself in the foot so that it can assume a new identity as a structural protein.