Tubulin binding of two 1-deaza-7,8-dihydropteridines with different biological properties: Enantiomers NSC 613862 (S)-(-) and NSC 613863 (R)-(+)
Several fluorescence properties of two enantiomers, NSC 613862 (S)-(-) and NSC 613863 (R)-(+), have been compared. Even though the two isomers showed the same fluorescence behavior in solution in different solvents, drastic differences were observed after binding to purified calf brain tubulin. Bind...
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Published in | Biochemistry (Easton) Vol. 32; no. 40; pp. 10675 - 10682 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Washington, DC
American Chemical Society
12.10.1993
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Subjects | |
Online Access | Get full text |
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Summary: | Several fluorescence properties of two enantiomers, NSC 613862 (S)-(-) and NSC 613863 (R)-(+), have been compared. Even though the two isomers showed the same fluorescence behavior in solution in different solvents, drastic differences were observed after binding to purified calf brain tubulin. Binding measurements for the two compounds were performed both by fluorescence spectroscopy and by column gel permeation, a direct method of measurement. For both isomers, the binding was characterized by the presence of one high-affinity binding site with an apparent association constant of (3.2 +/- 0.5) x 10(6) M-1 and (4.1 +/- 0.9) x 10(6) M-1 for the R- and S-isomer, respectively, and by several low-affinity sites. Both isomers were also shown to induce GTPase activity in tubulin. The high-affinity binding site seems to be the same for the two isomers. Moreover, fluorescence competition experiments suggest at least a partial overlap of the colchicine and podophyllotoxin site. To explain the differences in fluorescence behavior after binding to tubulin, we hypothesize that the R-isomer is positioned differently in its binding locus as compared with the S-isomer. |
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Bibliography: | istex:154A338F7B56A77B39229995589CF2B0B9F228D6 ark:/67375/TPS-XRDKQC3F-D ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi00091a018 |