Side‐chain thioamides as fluorescence quenching probes

Thioamides, single atom oxygen‐to‐sulfur substitutions of canonical amide bonds, can be valuable probes for protein folding and protease studies. Here, we investigate the fluorescence quenching properties of thioamides incorporated into the side‐chains of amino acids. We synthesize and incorporate Fmoc‐protected, solid‐phase peptide synthesis building blocks for introducing N^ε‐thioacetyl‐lysine and γ‐thioasparagine. Using rigid model peptides, we demonstrate the distance‐dependent fluorescence quenching of these thioamides. Furthermore, we describe attempts to incorporate of N^ε‐thioacetyl‐lysine into proteins expressed in Escherichia coli using amber codon suppression.     

Synthesis of the vasoactive intestinal peptide (VIP) I. The C-terminal cyanogen bromide fragment

The C-terminal cyanogen bromide fragment of VIP, Ala-Val-Lys-Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH₂ (all l), was synthesized to provide evidence for the correctness of the sequence proposed by Mutt and Said (1). The synthesis of this hendecapeptide (VIP_18–28) was carried out by coupling Z-Ala-Val-(Z)Lys to (Z)Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH₂. After removal of the protecting groups and purification, the synthetic material was indistinguishable from the natural fragment on paper chromatograms and electropherograms. Their identity was further confirmed by comparison of the products formed on enzymatic hydrolysis.     

Analysis of a cDNA from the neurologically active locus shaking-B (Passover) of Drosophila melanogaster.

We have isolated and sequenced a cDNA from the shaking-B locus of Drosophila melanogaster. The cDNA contains an open reading frame with extensive homology to another D. melanogaster gene, l(1)ogre. This suggests the existence of a new family of proteins required for the development and maintenance of the D. melanogaster nervous system.     

The evolution of protein domains and the organizational complexities of metazoans

There is an increasingly heated debate on the very existence of a 'universe of exons' and on the types of genomes that existed after the RNA world. What has been lost in the excitement are the biological issues that relate to the rapid emergence of phenotypic novelties. These issues can be examined by integrating data on protein domains and genomic evolution with the geochemical and palaeontological records.     

Breeding of a distiller's yeast by hybridization with a wine yeast

Summary Hybrids were constructed between auxotrophic mutants of a heterothallic distiller's strain and a homothallic wine yeast. The hybridization resulted in a significant increase in both ethanol production and tolerance against exogenous ethanol. The hybrids were heterogeneous in ploidy, probably due to segregation of aneuploids during culturing. Sporulation of the hybrids broke down the high productivity, producing spore clones that were mostly of various intermediate levels of performance. However, a meiotic product superior to both crossing partners was also found. The results demonstrate that fermentation capacity can be improved by crossing with a low performance strain. Offprint requests to: M. Sipiczki