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| | {{STRUCTURE_1alc| PDB=1alc | SCENE= }} | | {{STRUCTURE_1alc| PDB=1alc | SCENE= }} |
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| - | '''REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME'''
| + | ===REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME=== |
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| - | ==Overview==
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| - | 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. | + | The line below this paragraph, {{ABSTRACT_PUBMED_2769757}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 2769757 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_2769757}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Stuart, D I.]] | | [[Category: Stuart, D I.]] |
| | [[Category: Calcium binding protein]] | | [[Category: Calcium binding protein]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 10:25:06 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 17:05:27 2008'' |
Revision as of 14:05, 30 June 2008
Template:STRUCTURE 1alc
REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME
Template:ABSTRACT PUBMED 2769757
About this Structure
1ALC is a Single protein structure of sequence from Papio cynocephalus. Full crystallographic information is available from OCA.
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:2769757
Page seeded by OCA on Mon Jun 30 17:05:27 2008
