Influence of correlations on molecular recognition

The influence of the patchiness and correlations in the distribution of hydrophobic and polar residues at the interface between two rigid biomolecules on their recognition ability is investigated in idealised coarse-grained lattice models. A general two-stage approach is utilised where an ensemble of probe molecules is designed first and the recognition ability of the probe ensemble is related to the free energy of association with both the target molecule and a different rival molecule in a second step. The influence of correlation effects are investigated using numerical Monte Carlo techniques and mean field methods. Correlations lead to different optimum characteristic lengths of the hydrophobic and polar patches for the mutual design of the two biomolecules on the one hand and their recognition ability in the presence of other molecules on the other hand.Comment: 15 pages, 5 figure

A single mutation results in diploid gamete formation and parthenogenesis in a Drosophila yemanuclein-alpha meiosis I defective mutant

<p>Abstract</p> <p>Background</p> <p>Sexual reproduction relies on two key events: formation of cells with a haploid genome (the gametes) and restoration of diploidy after fertilization. Therefore the underlying mechanisms must have been evolutionary linked and there is a need for evidence that could support such a model.</p> <p>Results</p> <p>We describe the identification and the characterization of <it>yem¹</it>, the first <it>yem-alpha </it>mutant allele (V478E), which to some extent affects diploidy reduction and its restoration. Yem-alpha is a member of the Ubinuclein/HPC2 family of proteins that have recently been implicated in playing roles in chromatin remodeling in concert with HIRA histone chaperone. The <it>yem¹</it>mutant females exhibited disrupted chromosome behavior in the first meiotic division and produced very low numbers of viable progeny. Unexpectedly these progeny did not display paternal chromosome markers, suggesting that they developed from diploid gametes that underwent gynogenesis, a form of parthenogenesis that requires fertilization.</p> <p>Conclusions</p> <p>We focus here on the analysis of the meiotic defects exhibited by <it>yem¹</it>oocytes that could account for the formation of diploid gametes. Our results suggest that <it>yem¹</it>affects chromosome segregation presumably by affecting kinetochores function in the first meiotic division.</p> <p>This work paves the way to further investigations on the evolution of the mechanisms that support sexual reproduction.</p

Lipid binding proteins from the endosperms of wheat and Oats

A protein, designated lipid binding protein (LBP), has been purified from the petrol extracts of wheat and oat endosperms by hydrochloric acid precipitation in a non-polar medium and preparative electrophoresis. The purified LBP appeared to be homogeneous both by electrophoresis in sodium dodecyl sulphate-polyacrylamide (SDS-PAGE) gels (MW ca 14 500) and by electrophoresis (PAGE) at pH 3.2. The amino acid composition indicates a high degree of homology between the LBPs from the two sources, as judged by the indexes of Cornish-Bowden and of Harris and Teller. As in the case of thionin, a previously characterized polypeptide from the ether extract, LBP becomes ether-insoluble, chloroform-soluble by precipitation with acetone, and solubility in ether is restored by binding of digalactosyl diglyceride to the chloroform-soluble form