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Science 4 December 1998:
Vol. 282. no. 5395, p. 1781
DOI: 10.1126/science.282.5395.1781d
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This Week in Science

Figure 1

Studies of single molecules allow processes that would normally be hidden in studies of large ensembles of molecules to be revealed. Lu et al. (p. 1877) present evidence for a "memory effect" in the activity of the enzyme cholesterol oxidase. The rate of reaction could be determined with confocal microscopy because the enzyme's cofactor, flavin adenine dinucleotide, is fluorescent only in its oxidized form. The distribution of times for fluorescence to "switch on" varied considerably between single enzyme molecules, and even for a single enzyme molecule, the distribution of times deviates from exponential behavior in ways that can be attributed to slow fluctuations in the conformation of the molecule.




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Science. ISSN 0036-8075 (print), 1095-9203 (online)