期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：4
页码：1416-1420
DOI：10.1073/pnas.95.4.1416
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A method for sensitively monitoring enzyme kinetics and activities by using dual-color fluorescence cross-correlation spectroscopy is described. This universal method enables the development of highly sensitive and precise assays for real-time kinetic analyses of any catalyzed cleavage or addition reaction, where a chemical linkage is formed or cleaved through an enzyme's action between two fluorophores that can be discriminated spectrally. In this work, a homogeneous assay with restriction endonuclease EcoRI and a 66-bp double-stranded DNA containing the GAATTC recognition site and fluorophores at each 5' end is described. The enzyme activity can be quantified down to the low picomolar range (>1.6 pM) where the rate constants are linearly dependent on the enzyme concentrations over two orders of magnitude. Furthermore, the reactions were monitored on-line at various initial substrate concentrations in the nanomolar range, and the reaction rates were clearly represented by the Michaelis-Menten equation with a KM of 14 {+/-} 1 nM and a kcat of 4.6 {+/-} 0.2 min-1. In addition to kinetic studies and activity determinations, it is proposed that enzyme assays based on the dual-color fluorescence cross-correlation spectroscopy will be very useful for high-throughput screening and evolutionary biotechnology.
