Gensynthese

Synthesis of DNA Oligomers Possessing a Covalently Cross-Linked Watson-Crick Base Pair Model

Building bridges: A feasible solid-phase synthesis of antiparallel n-, h-, and H-type DNA oligomers has been demonstrated. The oligomers possess a CH₂ -bridged base-pair model that should be conformationally flexible, even after base pairing.

Various factors influencing the signal intensity of oligonucleotides in electrospray mass spectrometry

The quality of electrospray mass spectra of oligonucleotides often suffers from the low signal intensity and clustering with metal ions. This sometimes makes an exact determination of the molecular masses impossible. We describe here several factors contributing to these effects and show some means for their improvement.

Overexpression in Escherichia coli of a methionine-free designed interleukin-2 receptor (Tac protein) based on a chemically cleavable fusion protein

Several fusion proteins of our previously chemically synthesized gene encoding the interleukin-2-receptor alpha subunit (IL-2R alpha or Tac protein) were constructed. They were designed in order to be cleavable by cyanogen bromide. Thus, the original internal methionines of the IL-2R alpha were replaced by either alanine, valine, leucine or isoleucine, based on secondary structure predictions. Additionally, aspartate at position 6 was substituted for glutamate in order to stabilize the acid-labile Asp-Pro bond. Direct C-terminal fusion of total beta-galactosidase and portions thereof did not result in substantial amounts of the expected construct. Ternary fusions consisting of beta-galactosidase domains N- and C-terminally fused to the mutant synthetic methionine-free interleukin-2 receptor alpha subunit (synIL-2R alpha) yielded inclusion bodies amounting to 4-7% of the total protein. This first overexpression of a type I membrane receptor can be rationalized by the known beta-galactosidase structure models. The fusion protein can be cleaved with cyanogen bromide, isolated and the resulting synIL-2R alpha detected by Western blot analysis.