The prospects of protein nanocrystallography

The miniaturization of protein crystallography's experimental method has several advantages. Firstly, it reduces the amount of protein required for identifying crystallization conditions, allowing crystallographic studies of rare natural proteins and complexes. Secondly, higher levels of supersaturation can be obtained in very small volumes, allowing the exploration of additional crystallization conditions. Thirdly, there are indications that protein crystals grown in very small volumes may be better ordered. Fourthly, miniaturization and automation go hand in hand, opening the prospects of easier and more reproducible experimentation. Progress in the development of nanocrystallography is discussed and the remaining bottlenecks are highlighted

1UZ8: Anti-Lewis X Fab Fragment In Complex With Lewis X

The Lewis X trisaccharide is pivotal in mediating specific cell-cell interactions. Monoclonal antibody 291-2G3-A, which was generated from mice infected with schistosomes, has been shown to recognize the Lewis X trisaccharide. Here we describe the structure of the Fab fragment of 291-2G3-A, with Lewis X, to 1.8 A resolution. The crystallographic analysis revealed that the antigen binding site is a rather shallow binding pocket, and residues from all six complementary determining regions of the antibody contact all sugar residues. The high specificity of the binding pocket does not result in high affinity; the K(D) determined by isothermal calorimetry is 11 microM. However, this affinity is in the same range as for other sugar-antibody complexes. The detailed understanding of the antibody-Lewis X interaction revealed by the crystal structure may be helpful in the design of better diagnostic tools for schistosomiasis and for studying Lewis X-mediated cell-cell interactions by antibody interference

1UZ6: Anti-Lewis X Fab Fragment Uncomplexed

The Lewis X trisaccharide is pivotal in mediating specific cell-cell interactions. Monoclonal antibody 291-2G3-A, which was generated from mice infected with schistosomes, has been shown to recognize the Lewis X trisaccharide. Here we describe the structure of the Fab fragment of 291-2G3-A, with Lewis X, to 1.8 A resolution. The crystallographic analysis revealed that the antigen binding site is a rather shallow binding pocket, and residues from all six complementary determining regions of the antibody contact all sugar residues. The high specificity of the binding pocket does not result in high affinity; the K(D) determined by isothermal calorimetry is 11 microM. However, this affinity is in the same range as for other sugar-antibody complexes. The detailed understanding of the antibody-Lewis X interaction revealed by the crystal structure may be helpful in the design of better diagnostic tools for schistosomiasis and for studying Lewis X-mediated cell-cell interactions by antibody interference