1alc: Difference between revisions
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'''REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME''' | {{Structure | ||
|PDB= 1alc |SIZE=350|CAPTION= <scene name='initialview01'>1alc</scene>, resolution 1.7Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=CA:CALCIUM ION'>CA</scene> | |||
|ACTIVITY= | |||
|GENE= | |||
}} | |||
'''REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1ALC is a [ | 1ALC is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Papio_cynocephalus Papio cynocephalus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ALC OCA]. | ||
==Reference== | ==Reference== | ||
Refined structure of baboon alpha-lactalbumin at 1.7 A resolution. Comparison with C-type lysozyme., Acharya KR, Stuart DI, Walker NP, Lewis M, Phillips DC, J Mol Biol. 1989 Jul 5;208(1):99-127. PMID:[http:// | Refined structure of baboon alpha-lactalbumin at 1.7 A resolution. Comparison with C-type lysozyme., Acharya KR, Stuart DI, Walker NP, Lewis M, Phillips DC, J Mol Biol. 1989 Jul 5;208(1):99-127. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/2769757 2769757] | ||
[[Category: Papio cynocephalus]] | [[Category: Papio cynocephalus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: calcium binding protein]] | [[Category: calcium binding protein]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 09:59:13 2008'' | ||
Revision as of 10:59, 20 March 2008
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REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME
OverviewOverview
The solution of the structure of alpha-lactalbumin from baboon milk (Papio cynocephalus) at 4.5 A resolution using the isomorphous replacement method has been reported previously. Initial refinement on the basis of these low-resolution studies was not successful because of the poor isomorphism of the best heavy-atom derivative. Because of the striking similarity between the structure of lysozyme and alpha-lactalbumin, a more cautious molecular replacement approach was tried to refine the model. Using hen egg-white lysozyme as the starting model, preliminary refinement was performed using heavily constrained least-squares minimization in reciprocal space. The model was further refined using stereochemical restraints at 1.7 A resolution to a conventional crystallographic residual of 0.22 for 1141 protein atoms. In the final model, the root-mean-square deviation from ideality for bond distances is 0.015 A, and for angle distances it is 0.027 A. The refinement was carried out using the human alpha-lactalbumin sequence and "omit maps" calculated during the course of refinement indicated eight possible sequence changes in the baboon alpha-lactalbumin X-ray sequence. During the refinement, a tightly bound calcium ion and 150 water molecules, of which four are internal, have been located. Some of the water molecules were modelled for disordered side-chains. The co-ordination around the calcium is a slightly distorted pentagonal bipyramid. The Ca-O distances vary from 2.2 A to 2.6 A, representing a tight calcium-binding loop in the structure. The calcium-binding fold only superficially resembles the "EF-hand" and presumably has no evolutionary relationship with other EF-hand structures. The overall structure of alpha-lactalbumin is very similar to that of lysozyme. All large deviations occur in the loops where all sequence deletions and insertions are found. The C terminus appears to be rather flexible in alpha-lactalbumin compared to lysozyme. The experimental evidence supports the earlier predictions for the alpha-lactalbumin structure that were based upon the assumption that alpha-lactalbumin and lysozyme have similar three-dimensional structures, with minimal deletions and insertions. A detailed comparison of the two structures shows striking features as well as throwing some light on the evolution of these two proteins from a common precursor.
About this StructureAbout this Structure
1ALC is a Single protein structure of sequence from Papio cynocephalus. Full crystallographic information is available from OCA.
ReferenceReference
Refined structure of baboon alpha-lactalbumin at 1.7 A resolution. Comparison with C-type lysozyme., Acharya KR, Stuart DI, Walker NP, Lewis M, Phillips DC, J Mol Biol. 1989 Jul 5;208(1):99-127. PMID:2769757
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