1JFQ

ANTIGEN-BINDING FRAGMENT OF THE MURINE ANTI-PHENYLARSONATE ANTIBODY 36-71, "FAB 36-71"

Summary for 1JFQ

• Entry DOI: 10.2210/pdb1jfq/pdb
• Related: 6FAB
• Descriptor: ANTIGEN-BINDING FRAGMENT OF ANTI-PHENYLARSONATE ANTIBODY (3 entities in total)
• Functional Keywords: immunoglobulin, immune system
• Biological source: Mus musculus (house mouse); More
• Total number of polymer chains: 2
• Total formula weight: 47572.65

Authors

Parhami-Seren, B.,Viswanathan, M.,Strong, R.K.,Margolies, M.N. (deposition date: 2001-06-21, release date: 2002-02-27, Last modification date: 2024-11-13)

Primary citation

Parhami-Seren, B.,Viswanathan, M.,Strong, R.K.,Margolies, M.N.
Structural analysis of mutants of high-affinity and low-affinity p-azophenylarsonate-specific antibodies generated by alanine scanning of heavy chain complementarity-determining region 2.
J.Immunol., 167:5129-5135, 2001

PubMed Abstract: Alanine scanning was used to determine the affinity contributions of 10 side chain amino acids (residues at position 50-60 inclusive) of H chain complementarity-determining region 2 (HCDR2) of the somatically mutated high-affinity anti-p-azophenylarsonate Ab, 36-71. Each mutated H chain gene was expressed in the context of mutated (36-71L) and the unmutated (36-65L) L chains to also assess the contribution of L chain mutations to affinity. Combined data from fluorescence quenching, direct binding, inhibition, and capture assays indicated that mutating H:Tyr(50) and H:Tyr(57) to Ala in the 36-71 H chain results in significant loss of binding with both mutated (36-71L) or unmutated (36-65L) L chain, although the decrease was more pronounced when unmutated L chain was used. All other HCDR2 mutations in 36-71 had minimal effect on Ab affinity when expressed with 36-71 L chain. However, in the context of unmutated L chain, of H:Gly(54) to Ala resulted in significant loss of binding, while Abs containing Asn(52) to Ala, Pro(53) to Ala, or Ile(58) to Ala mutation exhibited 4.3- to 7.1-fold reduced affinities. When alanine scanning was performed instead on certain HCDR2 residues of the germline-encoded (unmutated) 36-65 Ab and expressed with unmutated L chain as Fab in bacteria, these mutants exhibited affinities similar to or slightly higher than the wild-type 36-65. These findings indicate an important role of certain HCDR2 side chain residues on Ab affinity and the constraints imposed by L chain mutations in maintaining Ag binding.

PubMed: 11673524

Experimental method

X-RAY DIFFRACTION (1.9 Å)