Synthesis Of Polythioesters Research Articles

3-Sulfinopropionyl-coenzyme A (3SP-CoA) desulfinase from Advenella mimigardefordensis DPN7(T): crystal structure and function of a desulfinase with an acyl-CoA dehydrogenase fold.

3-Sulfinopropionyl-coenzyme A (3SP-CoA) desulfinase (AcdDPN7; EC 3.13.1.4) was identified during investigation of the 3,3'-dithiodipropionic acid (DTDP) catabolic pathway in the betaproteobacterium Advenella mimigardefordensis strain DPN7(T). DTDP is an organic disulfide and a precursor for the synthesis of polythioesters (PTEs) in bacteria, and is of interest for biotechnological PTE production. AcdDPN7 catalyzes sulfur abstraction from 3SP-CoA, a key step during the catabolism of DTDP. Here, the crystal structures of apo AcdDPN7 at 1.89 Å resolution and of its complex with the CoA moiety from the substrate analogue succinyl-CoA at 2.30 Å resolution are presented. The apo structure shows that AcdDPN7 belongs to the acyl-CoA dehydrogenase superfamily fold and that it is a tetramer, with each subunit containing one flavin adenine dinucleotide (FAD) molecule. The enzyme does not show any dehydrogenase activity. Dehydrogenase activity would require a catalytic base (Glu or Asp residue) at either position 246 or position 366, where a glutamine and a glycine are instead found, respectively, in this desulfinase. The positioning of CoA in the crystal complex enabled the modelling of a substrate complex containing 3SP-CoA. This indicates that Arg84 is a key residue in the desulfination reaction. An Arg84Lys mutant showed a complete loss of enzymatic activity, suggesting that the guanidinium group of the arginine is essential for desulfination. AcdDPN7 is the first desulfinase with an acyl-CoA dehydrogenase fold to be reported, which underlines the versatility of this enzyme scaffold.

Biodegradation of the xenobiotic organic disulphide 4,4′-dithiodibutyric acid by Rhodococcus erythropolis strain MI2 and comparison with the microbial utilization of 3,3′-dithiodipropionic acid and 3,3′-thiodipropionic acid

Application of the non-toxic 3,3'-thiodipropionic acid (TDP) and 3,3'-dithiodipropionic acid (DTDP) as precursors for the microbial production of polythioesters (PTEs), a class of biologically persistent biopolymers containing sulphur in the backbone, was successfully established previously. However, synthesis of PTEs containing 4-mercaptobutyrate (4MB) as building blocks could not be achieved. The very harmful 4MB is not used as a PTE precursor or as the carbon source for growth by any known strain. As a promising alternative, the harmless oxidized disulfide of two molecules of 4MB, 4,4'-dithiodibutyric acid (DTDB), was employed for enrichments of bacterial strains capable of biodegradation. Investigation of novel precursor substrates for PTEs and comparison of respective strains growing on TDP, DTDP and DTDB as sole carbon source was accomplished. A broad variety of bacteria capable of using one of these organic sulphur compounds were isolated and compared. TDP and DTDP were degraded by several strains belonging to different genera, whereas all DTDB-utilizing strains were affiliated to the species Rhodococcus erythropolis. Transposon mutagenesis of R. erythropolis strain MI2 and screening of 7500 resulting mutants yielded three mutants exhibiting impaired growth on DTDB. Physiological studies revealed production of volatile hydrogen sulphide and accumulation of significant amounts of 4MB, 4-oxo-4-sulphanylbutanoic acid and succinic acid in the culture supernatants. Based on this knowledge, a putative pathway for degradation of DTDB was proposed: DTDB could be cleaved into two molecules of 4MB, followed by an oxidation yielding 4-oxo-4-sulphanylbutanoic acid. A putative desulphydrase probably catalyses the abstraction of sulphur, thereby generating succinic acid and hydrogen sulphide.

Linear polymers with sulfur in the main chain III. Synthesis of polythioesters by polycondensation of bis(4,4′‐mercaptophenyl)sulfide with various acid dichlorides and their properties

AbstractSynthesis and properties of sulfur‐containing linear polythioesters derived from bis(4,4′‐mercaptophenyl)sulfide (MPS) and various acid dichlorides (AC) have been studied to evaluate the effect of the thioester group in comparison with corresponding linear polyesters. Polycondensations between MPS and azelaoyl chloride (AZC) chosen as a model reaction system were investigated under various conditions by solution polycondensation, to find optimal conditions to get high molecular weight and quantitative yield. The obtained polymer using chloroform as a solvent indicated the highest molecular weight, determined by gel permeation chromatography (GPC). Thus the polythioesters from MPS and AC were synthesized under the above‐mentioned conditions. The thermal properties of polythioesters including the MPS moiety were evaluated by thermogravimetry/differential thermal analysis (TG/DTA), and differential scanning calorimetry (DSC). Those indicated that the polythioesters including the MPS moiety were crystalline polymers with relatively high heat resistance. These polythioesters were found to show an odd–even effect with the glass transition temperature, melting point, and oxygen permeability based on the methylene numbers. The tensile strength and storage modulus decreased with the number of methylene units. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 508–515, 2005

Linear polythioesters. XII. Products of polycondensation some isomeric di(mercaptomethyl)trimethylbenzenes with isophthaloyl and terephthaloyl chlorides

New polythioesters by interfacial polycondensation of 4,6-di(mercaptomethyl)-1,2,3-trimethyl-benzene, 3,5-di(mercaptomethyl)-1,2,4-trimethylbenzene, and 2,4-di(mercaptomethyl)-1,3,5-trimethylbenzene with isophthaloyl and terephthaloyl chlorides were obtained. Polycondensation was carried out under the same conditions as established earlier as optimum for synthesis of polythioesters from 2,5-di(mercaptomethyl)-1,4-dimethylbenzene and isophthaloyl chloride. The conditions of polycondensation were as follows: the organic phase benzene/hexane, ratio of aqueous to organic phase 1:1, presence of 100% excess of NaOH as hydrogen chloride acceptor, temperature of reaction 15°C, little excess of acid dichloride with addition time of 8 min, catalyst benzyltriethylammonium chloride. Yield, reduced viscosity and molecular weight for reaction products have been found. The structure of all polythioesters was determined from elemental analysis, infrared (IR) spectra and x-ray analysis. Thermal properties were defined from the curves of thermogravimetric analysis. Some mechanical and electrical properties of the polythioesters obtained from di(mercaptomethyl)-trimethylbenzenes and isophthaloyl chloride were determined.

Synthesis of Polythioesters and Polythiohydrazides

Various polythioesters and polythiohydrazides were synthesized by the polycondensation of dithiocarboxylic acid-O,O-diethyl esters with dihydrazides and diols in solution at a relatively low temperature. The polycondensation reaction took place with a much slower rate than that with diamines and the reactivity of dithiocarboxylic acid-O,O-diethyl ester with nucleophiles was in the following order: diamine>dihydrazide>diol.