1lb3: Difference between revisions

The first ferritin structure refined at the atomic level has been achieved, on recombinant mouse L-chain apoferritin (rMoLF) crystals. These latter, diffract to 1.2 A resolution under cryogenic conditions. When cryo-cooling, the sample, the thermal disorder usually observed at room temperature is, reduced and the low-temperature structure reveals several details, concerning the protein putative active sites and their properties. Within, the pores built up by the molecular three-fold symmetry axes, the iron, entry route to the ferritin cavity, residues H118, D131 and E134, exhibit, alternate conformations associated with the binding of partially hydrated, cadmium ions, a metal used as a crystallization agent. At the mineral, ferrihydrite nucleation center, the electron density maps evidence the, orientation of E57, E60, E61 and E64 glutamate side chains (whereas they, were observed highly disordered in previous ferritin structures determined, at room temperature) and allow a description of the site taking into, account the binding geometry of four Cd(2+) ions. Moreover, the side chain, of residue K140, lying in the vicinity of the ferrihydrite nucleation, center, is shown to interact with residue E61. As previously highlighted, this observation confirms the importance of K140 in the rMoLF sequence, as, being responsible for the low level of iron incorporation by mousel, L-chain ferritin compared to human L-chain ferritin. Finally, the, diffusion of small molecules within the ferritin cavity is illustrated, here by the presence of ordered molecules of glycerol used as a, cryo-protectant, which bind the inner cavity surface of the protein.

1LB3 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with SO4, CD and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Sites: NCL, SS1, SS2 and SS3. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1LB3 OCA].  

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