Hydroxydecanoate

A new pathway was recently engineered in vitro employing purified His6-tag-ged PhaCl and PhaC2 from P. aeruginosa plus a commercially available acyl-CoA synthetase allowing in vitro de novo PHA granules and in vitro synthesis of poly(3HD) from 3-hydroxydecanoate [74]. 

There is considerable interest in synthesizing copolymers. This is actually possible if organisms are confronted with mixtures of so-called related and unrelated substrates. Copolymers can also be synthesized from unrelated substrates, e.g., from glucose and gluconate. The 3-hydroxydecanoate involved in the polyester is formed by diversion of intermediates from de novo fatty-acid synthesis [41,42]. Related , in this context, refers to substrates for which the monomer in the polymer is always of equal carbon chain length to that of the substrate offered. Starting from related substrates, the synthesis pathway is closely connected to the fatty-acid /1-oxidation cycle [43]. In Pseudomonas oleovor-ans, for example, cultivated on octane, octanol, or octanoic acid, the synthesized medium chain length polyester consists of a major fraction of 3-hydroxyoc-tanoic acid and a minor fraction of 3-hydroxyhexanoic acid. If P. oleovorans is cultivated on nonane, nonanol, or nonanoic acid, the accumulated polyester comprises mainly of 3-hydroxynonanoate [44]. 

Lageveen et al. [41] showed that the monomer composition of aliphatic saturated poly(3HAMCL) produced by P. oleovorans is depended on the type of n-alkane used. It appeared that the n-alkanes were degraded by the subsequent removal of C2-units and it was therefore proposed that the /1-oxidation pathway was involved in poly(3HAMCL) biosynthesis. Preusting et al. [42] confirmed these results but also showed that with hexane as substrate some 3-hydroxyoctanoate and 3-hydroxydecanoate were produced, indicating that additional pathways were involved in poly(3HAMCL) biosynthesis (Table 1). 

C4 = 3-hydroxybutyric acid, C5 = 3-hydroxyvaleric acid, C6 = 3-hydroxyhexanoic acid, C7 = 3-hydroxyheptanoic acid, C8 = 3-hydroxyoctanoic acid, C9 = 3-hydroxynonanoic acid CIO = 3-hydroxydecanoic acid. 

When cells are grown on non-aliphatic substrates, such as glucose, fructose, acetate, or glycerol, these are converted to appropriate precursors that can be incorporated into poly(3HAMCL)s via fatty acid synthesis. The resulting PHAs have a monomer composition that is similar to that seen after growth on alkanes, often with 3-hydroxydecanoic acid as the major monomer. ( -Oxidation does not seem to play a role in the conversion of these substrates into poly(3HAMCL) since the addition of a -oxidation inhibitor did not affect the monomer composition [47]. 

The antibiotic viscosin from Pseudomonas viscosa (Scheme 8) is a cyclo-depsipeptide acyl-ated at the N-terminus with D-3-hydroxydecanoic add.[103 112] The C-terminal carboxy group is esterified with the hydroxy group of the Thr3 residue. The synthesis of this natural product presents the problem of an ester ring closure and was performed in two steps with initial solid-phase synthesis of the Thr3-0-branched linear intermediate followed by ring closure with formation of the amide bond.1 131... 

Pholipeptin was discovered by Ui et al. in 1997 as a novel phosphatidyl inositol speeific phospholipase C (PI-PLC) inhibitor from Pseudomonas sp. Pholipeptin is composed of five residues of D-leucine, two residues of D-serine, D- and L-aspartic acid, L-threonine, L-isoleucine and 3-hydroxydecanoic acid. Pholipeptin inhibits PI-PLC at 7.8pg/ml (IC50) in a non-competitive manner l Absolute configurations of the constituent amino acids were determined by using chiral HPLC without the racemic mixture of aspartic acid. The stereo chemistry of the two aspartie acids was distinguished by biosjmthetic incorporation of C-L-aspartic acid l... 

Qi, Q., Steinbtichel, A., and Rehm, B.H.A. (2000) In vitro synthesis of poly(3 -hydroxydecanoate) purification of type II polyhydroxyalkanoate synthases PhaCl and PhaC2 from Pseudomonas aeruginosa and development of an enzyme assay. Appl. Microbiol. Biotechnol., 54, 37-43. 

Serratamolide Serratia marcescens Gram-pos., gram-neg. yeast, fungi 514 L-Ser D- 3-hydroxydecanoic acid 311, 512... 

The rhamnolipid B (70) has the molecular structure of biosurfactants, comprising a hydrophilic part (rhamnose moiety) and a hydrophobic part ((3-hydroxydecanoate moiety) [151]. The biosurfactant property of this glycolipid was supposed to confer the ability to intercalate into and disrupt the zoospore plasma membrane [152,153]. However, other glycolipids such as sophorolipids and trehalose lipids, which have chemical properties similar to the rhamnolipids, did not show zoosporicidal activity at concentrations up to 1000 pg/ml. 

Rhamnolipids, in which one or two molecules of rhamnose are linked to one or two moleeules of 3-hydroxydecanoic acid, are the best-studied glycolipids. Production of rbamnose-containing glycolipids was first described by Jarvis and Johnson [10]. The main glycolipids produced by P. aeruginosa are rhamnolipids of the types 1 and 2, L-rhamnosyl-(3-hydroxydecanoyl-p-hydroxydecanoate and L-ihamnosyl-L-rhamnosyl- 3-hydroxydecanoyl- 3-hydroxydecanoate. Their structures can be seen in Fig. 1. The formation of rhamnolipid types 3 and 4 containing one 3-hydroxydecanoic acid with one and two rhamnose units, methyl ester derivatives of rhamnoUpids 1 and 2, and rhanmolipids with alternative fatty acid chains have also been reported [5]. 

NMR and MS/MS spectroscopy. Fellutamide A is composed of leucinal, P-hydroxyglutamine and asparagine esterified by 3-hydroxydecanoic acid. In fellutamide B, glutamine replaces P-hydroxyglutamine. P. fellutanum was previously isolated in the land environment [69]. 

The modification of DPI8 through the conjugation of (R)-3-hydroxydecanoic acid unfortunately resulted in greater cytotoxicity towards both cancer and normal cells. However, the new peptide derivative was still 3 x more toxic to cancer cells compared with human umbilical vein endothelial cells. 

In order to determine which one of the two routes is responsible for the formation of 3-hydroxydecanoate constituents, we cultivated P. putida on a combination of octanoate and [2- C] acetate. The resulting PHA consisted of the monomers 3-hydroxyhexanoate (8%), 3-hydroxyoctanoate (89%) and 3-hydroxydecanoate (3%). The labeling pattern of this polymer gives information on the origin of the monomers. 

KT21. Soapstock is recovered via the alkaline refinement process of oilseeds and contains phosphorus lipids, hydrateable and nonsaponifiable compounds, soaps of FFA, vitamins A and E, as well as carotenoid pigments. In their work, condensed corn-soluble basal medium was initially fed with biodiesel glycerol water but when the dissolved oxygen level rose above 10%, the medium was fed with sunflower soapstock. A shift in the monomer compositions from 3-hydroxydecanoate to 3-hydroxyoctanoate was observed when the medium was fed with sunflower soapstock. The final PHA also contained 3-hydroxytetradecanoate and 3-hydroxytetradecenoate monomers with a CDW and PHA content of 17 g/1 and 17%, respectively. 

To date, various block copolymers have been produced using biological systems. This includes poly(3HB-fo-4HB) [17], P(3HB)-f>-poly(3-hydroxyvalerate-co-3-hydroxyheptanoate) [18], PHB-f -poly(hydroxyhexanoate) [19], poly 3HB-fc-poly(3-hydroxyheptanoate) [P(3HP)] [20], P(3HP)-f -poly(4-hydroxybutyrate) [P(4HB)] [21], poly(3-hydroxyhexanoate)-fe-poly(3-hydroxydecanoate)-co-[3-hydroxydodecanoate (3HDD)] [22] and poly[3-HDD-f -poly(3-hydroxy-9-decanoate)] [23]. These studies were motivated by the fact that although random copolymers, such as poly(3HB-co-3HV) and poly(3HB-co-4HB), exhibit useful mechanical and thermal properties they suffer from a deterioration of polymer properties due to the effect of ageing. It was found that all block copolymers exhibited improved properties compared with the two relative homopolymers, random and blend polymers. Various... 

Fig. 2 Common PHA monomer structures. Short-chain-length monomers 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV). Medium-chain-length monomers 3-hydroxyhexanoate (3HHx), 3-hydroxyoctanoate (3HO), 3-hydroxydecanoate (3HD), 3-hydroxydodecanoate (3HDD)...

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