Open AccessThe Three-Dimensional Structure of the Fab′ Fragment of a Human Myeloma Immunoglobulin at 2.0-Å Resolution
Author(s) -
Roberto J. Poljak,
L. Mario Amzel,
B. L. Chen,
R. P. Phizackerley,
F.A. Saul
Publication year - 1974
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.71.9.3440
Subject(s) - immunoglobulin light chain , hypervariable region , immunoglobulin fab fragments , homology (biology) , peptide sequence , immunoglobulin heavy chain , myeloma protein , chemistry , antibody , fragment crystallizable region , stereochemistry , molecule , sequence (biology) , amino acid , complementarity determining region , biology , biochemistry , genetics , gene , organic chemistry
The structural analysis of the Fab′ fragment of human myeloma immunoglobulin IgGl(λ) New has been extended to a nominal resolution of 2.0 Å. Each of the structural subunits corresponding to the variable and to the constant homology regions of the light and heavy chains contains two irregular β-sheets which are roughly parallel to each other and surround a tightly packed interior of hydrophobic side chains. About 50-60% of the amino-acid residues are included in β-pleated sheets. Sequence alignments between the homology regions of Fab′ New obtained by comparison of their three-dimensional structures are given. Some of the sequence variations observed in light and heavy chains and the role of the regions of hypervariable sequence in defining the size and shape of the active site of different immunoglobulin molecules are discussed on the basis of the three-dimensional model of Fab′ New.