The first 6 residues of the biosurfactant lipopeptidolactone arthrofactin have the D configuration, yet none of the 11 modules of the nonribosomal peptide synthetase assembly line have epimerization domains. We show that the two-module ArfA subunit and the first module of the ArfB subunit, which act in tandem to produce the N-acyl-D-Leu1-D-Asp2-D-Thr3-S-protein intermediate, activate the L amin...

An enantioselective synthesis of the (1S,5R)-enantiomer of litseaverticillols A and B was accomplished in line with our previously reported synthetic pathway for their (1R,5S)-enantiomer. The use of "EtSCeCl2" prepared from EtSLi and CeCl3, instead of previously employed EtSLi itself, for the formation of thiol ester intermediates prevented any undesirable epimerization occurring in the process.

Six strains of lecithinase-lipase-negative Clostridia, isolated from human feces, were capable of oxidizing chenodeoxycholic acid to 3a-hydroxy-7-keto-5P-cholanoic acid and of epimerizing it to ursodeoxycholic acid. The identity of the reaction products was confirmed by coniparing their mass spectra, obtained by combined gas-liquid chromatography-mass spectrometry, with those of authentic refer...

Pen&e utilization in Aerobacter aerogenes has been shown from fermentation studies with Cl%beled pentoses (1, 2) and with cell extracts (3) to involve the conversion of the pentose to n-xylulose 5-phosphate, which is further metabolized via n-sedoheptulose 7-phosphate, n-fructose 6-phosphate, and intermediates of the Embden-Meyerhof pathway. Although Aerobacter aerogenes can grow on all eight o...

The biosynthetic pathways for patellamide and related natural products have recently been studied by structural biology. These pathways produce molecules that have a complex framework and exhibit a diverse array of activity due to the variability of the amino acids that are found in them. As these molecules are difficult to synthesize chemically, exploitation of their properties has been modest...

The mechanism of L-ribulose 5-phosphate 4-epimerase of Aerobacfer aerogenes has been investigated by determining the kinetic isotope effect (KT/KH) for the epimerization of D-[4-T]xylulose 5-phosphate in the presence of D-[l-14C]xylulose 5-phosphate. The ratio of T:14C was determined for the isolated L-ribulose derived from aliquots of an epimerization reaction mixture during its progress towar...