Stereochemistry

The synthesis of 10 new phosphoenolpyruvate (PEP) analogues with modifications in the phosphate and the carboxylate function is described. Included are two potential irreversible inhibitors of PEP-utilizing enzymes. One incorporates a reactive chloromethylphosphonate function replacing the phosphate group of PEP. The second contains a chloromethyl group substituting for the carboxylate function of PEP. An improved procedure for the preparation of the known (Z)- and (E)-3-chloro-PEP is also given.

11p system191 01-06-2013 35 3   Download

Flavoproteins are ubiquitous redox proteins that are involved in many biological processes.In the majority of flavoproteins, the flavin cofactor is tightlybut noncovalently bound.Reversible dissociation of flavoproteins into apo-proteinandflavinprostheticgroupyields valuable insights in flavoprotein folding, functionandmechanism.Replacement of the natural cofactorwithartificial flavins has proved tobe especially useful for the determination of the solvent acces-sibility, polarity, reaction stereochemistry and dynamic behaviour of flavoprotein active sites....

16p tumor12 20-04-2013 35 3   Download

Many pharmacologically important agents are assembled on multimodular nonribosomal peptide synthetases (NRPSs) whose modules comprise a set of core domains with all essential catalytic functions necessary for the incorporation and modification of one building block. Very often, d-amino acids are found in such products which, with few exceptions, are generated by the action of NRPS integrated epimerization (E) domains that alter the stereochemistry of the corresponding peptidyl carrier protein (PCP) bound l-intermediate....

15p fptmusic 12-04-2013 30 2   Download

Ribosomes position their substrate at stereochemistry suitable for peptide bond formation, and promote substrate-mediated cata-lysis. The linkage between substrate orientation, dominated by remote interactions, and a sizable symmetrical region identified in all known ribosome structures indicates a guided rotatory motion of aminoacylated-tRNAs along a ribosomal path leadings to the advance of nascent peptides into the protein exit tunnel at an extended conformation.

4p fptmusic 11-04-2013 24 3   Download

With the aim of extending our knowledge on the reaction pathways of Zn-metallothionein (MT) and apo-MT species in the presence of Hg(II), we monitored the titration of Zn7-MT, Zn4 -aMT and Zn3 -bMT proteins, at pH 7 and 3, with either HgCl2or Hg(ClO4 )2 by CD and UV-vis spectr-oscopy.

0p awards 05-04-2013 38 3   Download

Synthetic rhamnolipids, derived from a natural diacylated glycolipid, RL-2,214, produced by Burkholderia(Pseudomonas) plantarii, were analyzed biophysically. Changes in the chemical structures comprised variations in the length, the stereochemistry and numbers of the lipid chains, numbers of rhamnoses, and the occurrence of charged or neutral groups.

12p inspiron33 23-03-2013 31 3   Download

The biologically most significant genotoxic metabolite of the environmental pollutant benzo[a]pyrene (B[a]P), (+)-7R,8S-diol 9S,10R-epoxide, reacts chemically with guanine in DNA, resulting in the predominant formation of (+)-trans-B[a]P-N 2 -dG and, to a lesser extent, (+)-cis-B[a]P-N 2 -dG adducts.

14p galaxyss3 19-03-2013 30 3   Download