1bzq
From Proteopedia
(New page: 200px<br /> <applet load="1bzq" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bzq, resolution 2.8Å" /> '''COMPLEX OF A DROMEDA...) |
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caption="1bzq, resolution 2.8Å" /> | caption="1bzq, resolution 2.8Å" /> | ||
'''COMPLEX OF A DROMEDARY SINGLE-DOMAIN VHH ANTIBODY FRAGMENT WITH RNASE A'''<br /> | '''COMPLEX OF A DROMEDARY SINGLE-DOMAIN VHH ANTIBODY FRAGMENT WITH RNASE A'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1BZQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] and [http://en.wikipedia.org/wiki/Camelus_dromedarius Camelus dromedarius] with PO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http:// | + | 1BZQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] and [http://en.wikipedia.org/wiki/Camelus_dromedarius Camelus dromedarius] with <scene name='pdbligand=PO4:'>PO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BZQ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: ribonuclease]] | [[Category: ribonuclease]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Feb 15 15:33:57 2008'' |
Revision as of 13:33, 15 February 2008
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COMPLEX OF A DROMEDARY SINGLE-DOMAIN VHH ANTIBODY FRAGMENT WITH RNASE A
Overview
BACKGROUND: Camelid serum contains a large fraction of functional, heavy-chain antibodies - homodimers of heavy chains without light chains., The variable domains of these heavy-chain antibodies (VHH) have a long, complementarity determining region 3 (CDR3) loop that compensates for the, absence of the antigen-binding loops of the variable light chains (VL). In, the case of the VHH fragment cAb-Lys3, part of the 24 amino acid long CDR3, loop protrudes from the antigen-binding surface and inserts into the, active-site cleft of its antigen, rendering cAb-Lys3 a competitive enzyme, inhibitor. RESULTS: A dromedary VHH with specificity for bovine RNase A, cAb-RN05, has a short CDR3 loop of 12 amino acids and is not a competitive, enzyme inhibitor. The structure of the cAb-RN05-RNase A complex has been, solved at 2.8 A. The VHH scaffold architecture is close to that of a human, VH (variable heavy chain). The structure of the antigen-binding, hypervariable 1 loop (H1) of both cAb-RN05 and cAb-Lys3 differ from the, known canonical structures; in addition these H1 loops resemble each, other. The CDR3 provides an antigen-binding surface and shields the face, of the domain that interacts with VL in conventional antibodies., CONCLUSIONS: VHHs adopt the common immunoglobulin fold of variable, domains, but the antigen-binding loops deviate from the predicted, canonical structure. We define a new canonical structure for the H1 loop, of immunoglobulins, with cAb-RN05 and cAb-Lys3 as reference structures., This new loop structure might also occur in human or mouse VH domains., Surprisingly, only two loops are involved in antigen recognition; the CDR2, does not participate. Nevertheless, the antigen binding occurs with, nanomolar affinities because of a preferential usage of mainchain atoms, for antigen interaction.
About this Structure
1BZQ is a Single protein structure of sequence from Bos taurus and Camelus dromedarius with as ligand. Active as Pancreatic ribonuclease, with EC number 3.1.27.5 Full crystallographic information is available from OCA.
Reference
A single-domain antibody fragment in complex with RNase A: non-canonical loop structures and nanomolar affinity using two CDR loops., Decanniere K, Desmyter A, Lauwereys M, Ghahroudi MA, Muyldermans S, Wyns L, Structure. 1999 Apr 15;7(4):361-70. PMID:10196124
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