Structure elucidation and tentative formation pathway of a red colored enzymatic oxidation product of caffeic acid.

A red colored caffeic acid trimer was synthesized in model solution by enzymatic oxidation. The structure was elucidated by mass spectrometry and NMR spectroscopy and consisted of four carbon rings and two unsaturated acyl side chains. A formation pathway is suggested which includes the formation of a caffeic acid ortho-quinone followed by a Michael-type reaction, and radical coupling of a semiquinone of the formed dimer and a third caffeic acid molecule.

Regulation of nisin biosynthesis and immunity in Lactococcus lactis 6F3.

The biosynthetic genes of the nisin-producing strain Lactococcus lactis 6F3 are organized in an operon-like structure starting with the structural gene nisA followed by the genes nisB, nisT, and nisC, which are probably involved in chemical modification and secretion of the prepeptide (G. Engelke, Z. Gutowski-Eckel, M.

Biosynthesis of the lantibiotic nisin: genomic organization and membrane localization of the NisB protein.

Nisin produced by Lactococcus lactis 6F3 is used as a food preservative and is the most important member of a group of peptide-antibiotics containing lanthionine bridges (lantibiotics) (N. Schnell, K.-D.

Genetic analysis of epidermin biosynthetic genes and epidermin-negative mutants of Staphylococcus epidermidis.

Epidermin is produced by Staphylococcus epidermidis Tü3298 which harbors the 54-kb plasmid, pTü32. The plasmid contains not only the epidermin structural gene epiA, but also a flanking DNA region which is necessary for epidermin biosynthesis. The DNA sequence of this region revealed, in addition to epiA, five additional open reading frames, epiB, C, D, Q and P [Schnell, N.