1a3t
From Proteopedia
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'''STAPHYLOCOCCAL NUCLEASE, V23C VARIANT, COMPLEX WITH 2-FLUOROETHANE THIOL AND 3',5'-THYMIDINE DIPHOSPHATE''' | '''STAPHYLOCOCCAL NUCLEASE, V23C VARIANT, COMPLEX WITH 2-FLUOROETHANE THIOL AND 3',5'-THYMIDINE DIPHOSPHATE''' | ||
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[[Category: Richards, F M.]] | [[Category: Richards, F M.]] | ||
[[Category: Wynn, R.]] | [[Category: Wynn, R.]] | ||
| - | [[Category: | + | [[Category: Endonuclease]] |
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Nuclease]] |
| - | [[Category: | + | [[Category: Unnatural amino acid]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 09:46:06 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 06:46, 2 May 2008
STAPHYLOCOCCAL NUCLEASE, V23C VARIANT, COMPLEX WITH 2-FLUOROETHANE THIOL AND 3',5'-THYMIDINE DIPHOSPHATE
Overview
We have determined by X-ray crystallography the structures of several variants of staphylococcal nuclease with long flexible straight chain and equivalent length cyclic unnatural amino acid side chains embedded in the protein core. The terminal atoms in the straight side chains are not well defined by the observed electron density even though they remain buried within the protein interior. We have previously observed this behavior and have suggested that it may arise from the addition of side-chain vibrational and oscillational motions with each bond as a side chain grows away from the relatively rigid protein main chain and/or the population of multiple rotamers (Wynn R, Harkins P, Richards FM. Fox RO. 1996. Mobile unnatural amino acid side chains in the core of staphylococcal nuclease. Protein Sci 5:1026-1031). Reduction of the number of degrees of freedom by cyclization of a side chain would be expected to constrain these motions. These side chains are in fact well defined in the structures described here. Over-packing of the protein core results in a 1.0 A shift of helix 1 away from the site of mutation. Additionally, we have determined the structure of a side chain containing a single hydrogen to fluorine atom replacement on a methyl group. A fluorine atom is intermediate in size between methyl group and a hydrogen atom. The fluorine atom is observed in a single position indicating it does not rotate like methyl hydrogen atoms. This change also causes subtle differences in the packing interactions.
About this Structure
1A3T is a Single protein structure of sequence from Staphylococcus aureus. Full crystallographic information is available from OCA.
Reference
Comparison of straight chain and cyclic unnatural amino acids embedded in the core of staphylococcal nuclease., Wynn R, Harkins PC, Richards FM, Fox RO, Protein Sci. 1997 Aug;6(8):1621-6. PMID:9260275 Page seeded by OCA on Fri May 2 09:46:06 2008
