Spectroscopic studies of a hydrophobic peptide in membranelike environments

A hydrophobic linear peptide has been synthesized and studied over a range of environments using several complementary spectroscopic approaches, including nmr, CD, and vibrational spectroscopies. The sequence of this model peptide, carbobenzoxy-L-Pro-D-Phe-D-Ala-L-Pro-NHCH₃, was designed such that a small number of “folded” conformations, stabilized by intramolecular hydrogen bonding, would be accessible to it. Additionally, the extremely hydrophobic character of the peptide favors its interactions with hydrophobic regions of a membrane. The conformational impact of the membrane environment on the peptide, and the effect of the peptide on lipid organization have been explored both in micellar media and in vesicles. To facilitate nmr analysis, the peptide has been synthesized with one of the prolines perdeuterated. Results of these studies reveal that the peptide experiences a microenvironment of moderate polarity in micellar media and causes changes in lipid structure in a vesicle that are indicative of a hydrophobic peptide–lipid interaction.     

Chromosome integration of BAC (bacterial artificial chromosome): evidence of multiple rearrangements

This paper reports our attempts to characterize transgene integration sites in transgenic mouse lines generated by the microinjection of large (from 30 to 145 kb) pig DNA fragments encompassing a mammary specific gene, the whey acidic protein gene (WAP). Among the various methods used, the thermal asymmetric interlaced (TAIL-) PCR method allowed us (1) to analyze transgene/genomic borders and internal concatamer junctions for eleven transgenic lines, (2) to obtain sequence information for seven borders, (3) to place three transgenes in the mouse genome, and (4) to obtain sequence data for seven transgene junctions in concatamers. Finally, we characterized various rearrangements in the borders and the inner parts of the transgene. The possibility of such complex rearrangements should be carefully considered when transgenic animals are produced with large genomic DNA fragments.