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1lil
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(New page: 200px<br /> <applet load="1lil" size="450" color="white" frame="true" align="right" spinBox="true" caption="1lil, resolution 2.65Å" /> '''BENCE JONES PROTEIN...)
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Revision as of 15:55, 12 November 2007
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BENCE JONES PROTEIN CLE, A LAMBDA III IMMUNOGLOBULIN LIGHT-CHAIN DIMER
Overview
The structure of protein Cle, a human light-chain dimer from the lambdaIII, subgroup, was determined using 2.6 A data; the R value is 18.4%. The, structure was solved, after a false start, by molecular replacement with, the lambdaII/V Mcg protein as a search structure. When the refinement did, not proceed beyond an R value of 27%, it was discovered that while the, constant domains were in their correct positions in the unit cell, the, incorrect variable domains were used for defining the molecule. The, correct solution required a rotation of 180 degrees around the local, twofold axis that relates the two constant domains of the dimer. The, correct variable domain positions overlap about 70% of the same volume as, the incorrect ones of a symmetry-related molecule. The refinement, distorted the geometries of the domains. Though the constant domains were, in their correct positions, the r.m.s. (root-mean-square) deviation of the, Calpha atom position was 1.2 A when the two constant domains were, compared. For the correct structure, this value is 0.5 A. The phi and psi, angles, the r.m.s. chiral value and the free R value, even when calculated, a posteriori, were good indicators of the correctness of the structure., The quaternary structure of the Cle molecule is similar to that in Mcg, (crystallized from ammonium sulfate); the elbow bend is 115 degrees., However, the arrangement of the variable domains differs from that, observed in other variable domain dimers. The variable domains of Cle are, 0.7 A closer than in Mcg or variable dimer Rei. The hydrogen bonding at, the interface of the two domains is novel. Residues Tyr36 from both, monomers form a hydrogen bond that is part of a network with the Gln89, residues from both monomers. For the first time hydrogen bonds were, observed between the main-chain peptide N and O atoms of the, complementarity-determining region CDR2 and CDR3 segments of both, monomers.
About this Structure
1LIL is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Pitfalls of molecular replacement: the structure determination of an immunoglobulin light-chain dimer., Huang DB, Ainsworth C, Solomon A, Schiffer M, Acta Crystallogr D Biol Crystallogr. 1996 Nov 1;52(Pt 6):1058-66. PMID:15299564
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