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| - | [[Image:1d44.jpg|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1d44| PDB=1d44 | SCENE= }} | | {{STRUCTURE_1d44| PDB=1d44 | SCENE= }} |
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| - | '''DNA DODECAMER C-G-C-G-A-A-T-T-C-G-C-G/HOECHST 33258 COMPLEX: 0 DEGREES C, PIPERAZINE DOWN'''
| + | ===DNA DODECAMER C-G-C-G-A-A-T-T-C-G-C-G/HOECHST 33258 COMPLEX: 0 DEGREES C, PIPERAZINE DOWN=== |
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| - | ==Overview==
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| - | The crystal structure of the complex of Hoechst 33258 and the DNA dodecamer C-G-C-G-A-A-T-T-C-G-C-G has been solved from X-ray data collected at three different low temperatures (0, -25, and -100 degrees C). Such temperatures have permitted collection of higher resolution data (2.0, 1.9, and 2.0 A, respectively) than with previous X-ray studies of the same complex. In all three cases, the drug is located in the narrow central A-A-T-T region of the minor groove. Data analyses at -25 and -100 degrees C (each with a 1:1 drug/DNA ratio in the crystallizing solution) suggest a unique orientation for the drug. In contrast, two orientations of the drug were found equally possible at 0 degrees C with a 2:1 drug/DNA ratio in solution. Dihedral angles between the rings of Hoechst 33258 appear to change in a temperature-dependent manner. The drug/DNA complex is stabilized by single or bifurcated hydrogen bonds between the two N-H hydrogen-bond donors in the benzimidazole rings of Hoechst and adenine N3 and thymine O2 acceptors in the minor groove. A general preference for AT regions is conferred by electrostatic potential and by narrowing of the walls of the groove. Local point-by-point AT specificity follows from close van der Waals contacts between ring hydrogen atoms in Hoechst 33258 and the C2 hydrogens of adenines. Replacement of one benzimidazole ring by purine in a longer chain analogue of Hoechst 33258 could make that particular site GC tolerant in the manner observed at imidazole substitution for pyrrole in lexitropsins. | + | The line below this paragraph, {{ABSTRACT_PUBMED_1718416}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 1718416 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_1718416}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Complexed with drug]] | | [[Category: Complexed with drug]] |
| | [[Category: Double helix]] | | [[Category: Double helix]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:25:52 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 22:22:06 2008'' |
Revision as of 19:22, 30 June 2008
Template:STRUCTURE 1d44
DNA DODECAMER C-G-C-G-A-A-T-T-C-G-C-G/HOECHST 33258 COMPLEX: 0 DEGREES C, PIPERAZINE DOWN
Template:ABSTRACT PUBMED 1718416
About this Structure
Full crystallographic information is available from OCA.
Reference
Low-temperature crystallographic analyses of the binding of Hoechst 33258 to the double-helical DNA dodecamer C-G-C-G-A-A-T-T-C-G-C-G., Quintana JR, Lipanov AA, Dickerson RE, Biochemistry. 1991 Oct 22;30(42):10294-306. PMID:1718416
Page seeded by OCA on Mon Jun 30 22:22:06 2008
