Advances in single molecule techniques could revolutionise the study of enzymes, according to researchers from the Netherlands and Belgium, and indicate that enzymes are only active in short bursts.

Roeland Nolte and Alan Rowan from Radboud University Nijmegen and colleagues from the Katholieke Universiteit Leuven have highlighted recent advances in single enzyme experiments that provide improved means to investigate enzyme behaviour.

Studies on enzyme activity previously concentrated on enzymes in bulk aqueous solution. These studies provided only average measurements and did not give information on the contributions of individual molecules.

The first single enzyme investigations were performed in the early sixties, but it is only recently that advances in technologies such as fluorescent microscopy and scanning probe technologies have enabled major progress to take place. 'The newly developed single molecule techniques open the way to unravel in detail the pathways by which enzymes operate,' write Nolte and Rowan.

Nolte, Rowan and colleagues measured the enzyme activity of a single enzyme molecule for long periods and observed its conformational motion. The enzyme molecule was found to move between numerous conformational states, only a few of which were catalytically active. The enzyme is inactive for over 90 percent of the time and is active in very small bursts.

'As scanning probe microscopy has revolutionized the field of material science, it is without doubt that single enzyme studies in real time will have a similar effect in the field of enzymology,' write Nolte and Rowan.

Sarah Dixon