• Crystallographic analysis of the NNA7 Fab and proposal for the mode of human blood-group recognition.

Crystallographic analysis of the NNA7 Fab and proposal for the mode of human blood-group recognition.

Acta crystallographica. Section D, Biological crystallography (2005-10-06)
Kefang Xie, Shuh Chyung Song, Steven L Spitalnik, Joseph E Wedekind

The NNA7 Fab antibody fragment recognizes the human N-type blood-group antigen comprised of the N-terminal glycopeptide of glycophorin A (GPA). A mutant form of this Fab fragment, NNA7-G91S, exhibits markedly reduced antigen binding. To provide insight into how these Fab fragments recognize this glycopeptide antigen, the crystal structures of NNA7 and NNA7-G91S were solved and refined to 1.83 and 1.97 A resolution, respectively. Both molecules are composed of the same heavy (H) chain Fd fragment, but each contains a slightly different light (L) chain owing to the G91S substitution. Specifically, the G91S mutation pushes the backbone of the neighboring H chain away from complementarity-determining region 3 (CDR3) of the L-chain variable region, allowing an additional glycerol cryoprotectant molecule to enter the antigen-combining site near the putative location of O-linked glycosylation. Each Fab fragment also possesses a well defined 2-(N-morpholino)ethanesulfonic acid (MES) molecule trapped in its antigen-combining site, as well as a crystallographic symmetry-related molecule comprising an amino-acid sequence that is virtually identical to the N-terminus of GPA. The MES molecule interacts with the H-chain CDR in a manner reminiscent of antibody-carbohydrate complexes. These results suggest a model for recognition of the glycopeptide antigen that accounts for the deleterious effect of the G91S substitution.

Product Number
Product Description

MES hydrate, ≥99.5% (titration), pH 2.5-4.0 (0.5 M in H2O), BioXtra
MES hydrate, BioPerformance Certified, suitable for cell culture, ≥99.5%
MES hydrate, ≥99.5% (titration)
MES hydrate, BioUltra, ≥99.5% (T)
MES, low moisture content, ≥99% (titration)
MES sodium salt, ≥99% (titration)
MES sodium salt, BioReagent, ≥99% (titration), crystalline
MES sodium salt
MES solution, BioUltra, for molecular biology, 0.5 M in H2O
MES sodium salt, BioPerformance Certified, suitable for cell culture