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| | {{STRUCTURE_1l5t| PDB=1l5t | SCENE= }} | | {{STRUCTURE_1l5t| PDB=1l5t | SCENE= }} |
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| - | '''Crystal Structure of a Domain-Opened Mutant (R121D) of the Human Lactoferrin N-lobe Refined From a Merohedrally-Twinned Crystal Form.'''
| + | ===Crystal Structure of a Domain-Opened Mutant (R121D) of the Human Lactoferrin N-lobe Refined From a Merohedrally-Twinned Crystal Form.=== |
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| - | ==Overview==
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| - | Human lactoferrin is an iron-binding protein with a bilobal structure. Each lobe contains a high-affinity binding site for a single Fe(3+) ion and an associated CO(3)(2-) ion. Although iron binds very tightly, it can be released at low pH, with an accompanying conformational change in which the two domains move apart. The Arg121Asp (R121D) mutant of the N-lobe half-molecule of human lactoferrin was constructed in order to test whether the Asp121 side chain could substitute for the CO(3)(2-) ion at the iron-binding site. The R121D mutant protein was crystallized in its apo form as it lost iron during crystallization. The crystals were also merohedrally twinned, with a twin fraction close to 0.5. Starting from the initial molecular-replacement solution [Breyer et al. (1999), Acta Cryst. D55, 129-138], the structure has been refined at 3.0 A resolution to an R factor of 13.9% (R(free) of 19.9%). Despite the moderate resolution, the high solvent content and non-crystallographic symmetry contributed to electron-density maps of excellent quality. Weakened iron binding by the R121D mutant is explained by occlusion of the anion-binding site by the Asp side chain. The opening of the two domains in the apoR121D structure (a rotation of 54 degrees ) closely matches that of the N-lobe in full-length lactoferrin, showing that the extent of the conformational change depends on properties inherent to the N-lobe. Differences in the C-terminal portion of the N-lobe (residues 321-332) for apoR121D relative to the closed wild-type iron-bound structure point to the importance of this region in stabilizing the open form.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_12037297}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12037297 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12037297}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: N-lobe]] | | [[Category: N-lobe]] |
| | [[Category: Twinning]] | | [[Category: Twinning]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 23:34:28 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 11:46:06 2008'' |
Revision as of 08:46, 2 July 2008
Template:STRUCTURE 1l5t
Crystal Structure of a Domain-Opened Mutant (R121D) of the Human Lactoferrin N-lobe Refined From a Merohedrally-Twinned Crystal Form.
Template:ABSTRACT PUBMED 12037297
About this Structure
1L5T is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structure of a domain-opened mutant (R121D) of the human lactoferrin N-lobe refined from a merohedrally twinned crystal form., Jameson GB, Anderson BF, Breyer WA, Day CL, Tweedie JW, Baker EN, Acta Crystallogr D Biol Crystallogr. 2002 Jun;58(Pt 6 Pt 2):955-62. Epub, 2002 May 29. PMID:12037297
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