Fluorescence energy transfer between heterologous active sites of affinity-labeled aspartokinase of Escherichia coli
- 19 April 1977
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 16 (8) , 1548-1554
- https://doi.org/10.1021/bi00627a003
Abstract
The distance between aspartokinase [EC 2.7.2.4] and homoserine dehydrogenase [EC 1.1.1.3] active sites was determined using fluorescence energy transfer between modified substrates. The fluorescent 1,N(6)-ethenoadenosine 5''-triphosphate was bound at the kinase active site by Co(III) affinity labeling. Reduced thionicotinamide adenine dinucleotide phosphate quenched the fluorescence of bound nucleotide. Fluorescence depolarization measurements led to a delimitation of the value of the dipolar orientation factor to the range 0.3-2.8. The distance between the fluorescent probe and the quencher was 29 .+-. 4 .ANG.. In the presence of threonine, this distance increased to 36 .+-. 5 .ANG.. Threonine binding increased the intersite distance by .apprx. 7 .ANG. or caused a reorientation of the probe at the dehydrogenase site.This publication has 11 references indexed in Scilit:
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