Epimerization of (−)-Isodihydrocarvone to (−)-Dihydrocarvone byPseudomonas fragiIFO 3458

Dev094037 3458..3471

Distinguishing self from non-self plays a crucial role in safeguarding the germlines of metazoa from mobile DNA elements. Since their discovery less than a decade ago, Piwi-interacting RNAs (piRNAs) have been shown to repress transposable elements in the germline and, hence, have been at the forefront of research aimed at understanding the mechanisms that maintain germline integrity. More recen...

No . 3458 Nutritional value of rapeseed oil

Epimerization of erythromycin derivatives.

Dirithromycin (3) isomerizes upon dissolution in different solvents. From X-ray analysis of V-T 108, an analogue of dirithromycin, and comparative 1H and 13C NMR, and MS data, the isomer of dirithromycin was confirmed to be the C-16-(S)-epimer. The ratio of the two epimers at equilibrium conditions was approximately 8:2 (R/S) in methanol at room temperature.

Racemization and epimerization.

In recent reports (I ) the term racemization is used inappropriately. It is stated in both reports that Lisoleucine racemizes to D-alloisoleucine. This reaction is epimerization, not racemization. Racemization of L-iSOleucine results in the formation of DLisoleucine. As stated in Eliel (2): "'racemization is the process of producing a racemic modification starting with one of the pure enantiome...

Epimerization and stereochemistry of avoparcin.

The epimerization of avoparcin entities is discussed in some detail. The absolute stereochemistry of avoparcin is now known since the N-methyl terminal amino acid of the aglycone has been isolated and shown to exhibit negative optical rotation and hence has the R-configuration. The same amino acid has been isolated from an epimerized solution of avoparcin and found to have positive rotation and...