title: Crystallization and preliminary X-ray diffraction data of an anti-angiotensin II Fab and of the peptide-Fab complex.
abstract: mAb-131 is a monoclonal antibody that binds with high affinity (K alpha = 7.4 x 10(9) M-1) to the 8-residue peptide hormone angiotensin II, the major effector of the renin/angiotensin system. mAb-131 is a member of a well characterized idiotypic antibody network since it was raised as an anti-anti-idiotype of an antibody raised against angiotensin II. mAb-131 Fabs prepared with papain contain four major charge isoforms that can be separated by pH gradient elution from an anion-exchange column. Diffraction quality isomorphous crystals of two of the isoforms and of the Fab.peptide complexes have been grown. The crystals diffract to 3.5 A resolution, are tetragonal, space group P4(1) (or P4(3] with cell dimensions a = b = 78.6 A, c = 125.2 A, and have two Fab molecules per asymmetric unit. By using a different buffer, a second crystal form has been grown which diffracts to 3.3 A. It also belongs to space group P4(1) (or P4(3] but has cell dimensions of a = b = 109.6 A and c = 125.2 A. Knowledge of the three-dimensional structure of this Fab and of the peptide.Fab complex will give insight into two problems: 1) the recognition of small peptide hormones (which exist as random coils in solution) with high affinity by proteins, and 2) the nature of conservation of antibody combining sites in idiotypic networks.
authors.affiliation: Department of Biophysics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: K C
authors.initials: KC
authors.lastname: Garcia
authors.forename: P
authors.initials: P
authors.lastname: Ronco
authors.forename: P J
authors.initials: PJ
authors.lastname: Verroust
authors.forename: L M
authors.initials: LM
authors.lastname: Amzel
mesh_terms: D000804:Angiotensin II / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000302:isolation & purification; D000936:Antigen-Antibody Complex / Q000302:isolation & purification; D003460:Crystallization; D007140:Immunoglobulin Fab Fragments / Q000302:isolation & purification; D007525:Isoelectric Focusing; D011487:Protein Conformation; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D007140:Immunoglobulin Fab Fragments; D000804:Angiotensin II