The X-ray crystal structure of recombinant human monocyte chemoattractant protein (MCP-1) has been solved in two crystal forms. One crystal form (P), refined to 1.85 A resolution, contains a dimer in the asymmetric unit, while the other (I) contains a monomer and was refined at 2.4 A. Although both crystal forms grow together in the same droplet, the respective quaternary structures of the protein differ dramatically. In addition, both X-ray structures differ to a similar extent from the solution structure of MCP-1. Such extent of variability of quaternary structures is unprecedented. In the crystal structures, the well-ordered N termini of MCP-1 form 3(10)-helices. Comparison of the three MCP-1 structures revealed a direct correlation between the main-chain conformation of the first two cysteine residues and the quaternary arrangements. These data can be used to explain the structural basis for the assignment of residues responsible for biological activity.

No abstract

Thin plates of L‐lysyl‐L‐valine hydrochloride (C11H24N3O3Cl) were obtained using the vapour diffusion technique and analysed by X‐ray diffraction. The unit cell is orthorhombic, space group P212121, a = 5.465(6)Å, b = 19.657(4) Å, c = 13.522(2) Å, V = 1452.6(2.1) Å3 and Z = 4. The structure was solved by direct methods and refined to an agreement factor of 6.7% for 939 reflections with I > 3 σ(I). The lysine side chain conformation (g‐ g‐ tt) has never been found in peptide crystal structures, although it has been reported to occur in proteins. A network of hydrogen bonds between peptide molecules spreads along the a and c directions while no direct bonds are observed to occur between peptides along the b axis direction. This asymmetric pattern of interactions correlates with the crystal morphology.

No abstract

No abstract