1rxh: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1rxh.gif|left|200px]] | [[Image:1rxh.gif|left|200px]] | ||
<!-- | |||
The line below this paragraph, containing "STRUCTURE_1rxh", creates the "Structure Box" on the page. | |||
You may change the PDB parameter (which sets the PDB file loaded into the applet) | |||
or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |||
or leave the SCENE parameter empty for the default display. | |||
--> | |||
{{STRUCTURE_1rxh| PDB=1rxh | SCENE= }} | |||
}} | |||
'''Crystal structure of streptavidin mutant L124R (M1) complexed with biotinyl p-nitroanilide (BNI)''' | '''Crystal structure of streptavidin mutant L124R (M1) complexed with biotinyl p-nitroanilide (BNI)''' | ||
| Line 32: | Line 29: | ||
[[Category: Raboy, B.]] | [[Category: Raboy, B.]] | ||
[[Category: Wilchek, M.]] | [[Category: Wilchek, M.]] | ||
[[Category: | [[Category: Avidin]] | ||
[[Category: | [[Category: Pseudo enzymatic activity]] | ||
[[Category: | [[Category: Streptavidin]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 08:01:26 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 08:01, 3 May 2008
Crystal structure of streptavidin mutant L124R (M1) complexed with biotinyl p-nitroanilide (BNI)
OverviewOverview
Avidin enhances the hydrolysis of biotinyl p-nitrophenyl ester (BNP) under mild alkaline conditions, whereas streptavidin prevents hydrolysis of BNP up to pH 12. Recently, we imposed hydrolytic activity on streptavidin by rational mutagenesis, based on the molecular elements responsible for the hydrolysis by avidin. Three mutants were designed, whereby the desired features, the distinctive L124R point mutation (M1), the L3,4 loop replacement (M2), and the combined mutation (M3), were transferred from avidin to streptavidin. The crystal structures of the mutants, in complex with biotinyl p-nitroanilide (BNA), the stable amide analogue of BNP, were determined. The results demonstrate that the point mutation alone has little effect on hydrolysis, and BNA exhibits a conformation similar to that of streptavidin. Substitution of a lengthier L3,4 loop (from avidin to streptavidin), resulted in an open conformation, thus exposing the ligand to solvent. Moreover, the amide bond of BNA was flipped relative to that of the streptavidin and M1 complexes, thus deflecting the nitro group toward Lys-121. Consequently, the leaving group potential of the nitrophenyl group of BNP is increased, and M2 hydrolyzes BNP at pH values >8.5. To better emulate the hydrolytic potential of avidin, M3 was required. The combination of loop replacement and point mutation served to further increase the leaving group potential by interaction of the nitro group with Arg-124 and Lys-121. The information derived from this study may provide insight into the design of enzymes and transfer of desired properties among homologous proteins.
About this StructureAbout this Structure
1RXH is a Single protein structure of sequence from Streptomyces avidinii. Full crystallographic information is available from OCA.
ReferenceReference
Structural elements responsible for conversion of streptavidin to a pseudoenzyme., Eisenberg-Domovich Y, Pazy Y, Nir O, Raboy B, Bayer EA, Wilchek M, Livnah O, Proc Natl Acad Sci U S A. 2004 Apr 20;101(16):5916-21. Epub 2004 Apr 12. PMID:15079055 Page seeded by OCA on Sat May 3 08:01:26 2008