Acid Chain Length Research Articles

Some observations on the use of fatty alcohols and fatty acids to increase the consistency of oil-in-water emulsions.

Abstract A range of fatty alcohols and fatty acids of different chain lengths and chemical configuration has been examined to determine which of these may be usefully employed to increase the consistency of liquid paraffin-in-water emulsions stabilized by condensed complex films. Of the alcohols, a straight chain of 16 carbon atoms (cetyl alcohol) or a physical mixture of straight chains of 16 and 18 carbon atoms (cetostearyl alcohol) gave maximum bodying action. To a lesser extent a straight chain of 14 carbon atoms (myristyl alcohol) and in some cases a straight chain of 12 carbon atoms (lauryl alcohol) also increased the consistency of emulsions. Other homologues (C8, C10 and C18), unsaturated or branched chain alcohols and fatty acids were, in general, found to be of little value for this purpose.

Efficient Gene Silencing by Self-Assembled Complexes of siRNA and Symmetrical Fatty Acid Amides of Spermine

Gene silencing by siRNA (synthetic dsRNA of 21-25 nucleotides) is a well established biological tool in gene expression studies and has a promising therapeutic potential for difficult-to-treat diseases. Five fatty acids of various chain length and oxidation state (C12:0, C18:0, C18:1, C18:2, C22:1) were conjugated to the naturally occurring polyamine, spermine, and evaluated for siRNA delivery and gene knock-down. siRNA delivery could not be related directly to gene silencing efficiency as N4,N9-dierucoyl spermine resulted in higher siRNA delivery compared to N4,N9-dioleoyl spermine. GFP silencing in HeLa cells showed that the unsaturated fatty acid amides are more efficient than saturated fatty acid amides, with N4,N9-dioleoyl spermine resulting in the most efficient gene silencing in the presence of serum. The alamarBlue cell viability assay showed that fatty acid amides of spermine have good viability (75%–85% compared to control) except N4,N9-dilauroyl spermine which resulted in low cell viability. These results prove that unsaturated fatty acid amides of spermine are efficient, non-toxic, non-viral vectors for siRNA mediated gene silencing.

Synthesis of fatty acid sterol esters using cholesterol esterase from Trichoderma sp. AS59

We recently reported the characterization of novel cholesterol esterase (EC. 3.1.1.13) from Trichoderma sp. and preliminary work on sterol ester synthesis. In the present study, we further examined the enzyme ability to synthesize cholesterol esters from cholesterol and free fatty acids of various chain lengths, and compared the fatty acid specificity in synthesis with that in hydrolysis. The enzyme catalyzed the synthesis of medium- and long-chain fatty acid cholesterol esters, but failed to synthesize short-chain fatty acid esters. The fatty acid specificities in the synthesis and hydrolysis of cholesterol esters were entirely different from each other. Unlike other lipolytic enzymes, the enzyme was largely independent of water content in the synthesis of cholesterol oleate, and it achieved near-complete esterification in the presence of an equimolar excess of oleic acid. Of additional interest is the finding that the addition of n-hexane markedly enhanced the esterification activities on all the medium- and long-chain saturated fatty acids used. Based on these findings, we attempted to synthesize stigmasterol stearate as a food additive to lower cholesterol levels in blood plasma, and found that the enzyme catalyzed effective synthesis of the ester without the need of dehydration during the reaction, indicating the potential utility of the enzyme in the food industry.

The effects of hydroxy fatty acids on the hyphal branching of germinated spores of AM fungi

Two hydroxy fatty acids, tentatively identified previously in carrot root exudates, were tested for their effects on hyphal growth of the arbuscular mycorrhizal (AM) fungus, Gigaspora gigantea (Nicol. and Gerd.) Gerdemann and Trappe. Best results were achieved with a long-term bioassay (7–8 d) with nanomolar concentrations throughout the Petri dish in contrast to the rapid microinjection bioassay (16–24 h) in which nanogram quantities were injected near growing hyphal tips. When 5 nM 2-hydroxy fatty acids of various chain length were tested, the length of the hydroxyl fatty acid was significant since only 2-hydroxytetradecanoic acid (2OH-TDA) and to a slightly lesser degree, 2-hydroxydodecanoic acid (2OH-DDA) induced a hyphal growth response while 2-hydroxydecanoic acid (2OH-DA) and 2-hydroxyhexadecanoic (2OH-HDA) acid did not. The position of the hydroxyl group was critical since 5 nM 3-hydroxytetradecanoic acid (3OH-TDA) had no effect on hyphal growth. The length of the non-hydroxy containing straight chain fatty acid, per se, did not appear significant since none of these fatty acids had an effect on hyphal growth. The morphological growth response promoted by 2OH-TDA consisted of multiple lateral branches, spaced fairly regularly apart, along the primary germ tubes as well as some lateral branch formation off the major secondary hyphae. This growth response was identical to that observed when germinated spores were allowed to grow towards cultured carrot roots in vitro. This response to 2OH-TDA also was observed with an unidentified Gigaspora species but no morphological response was observed with Glomus intraradices Schenck and Smith. The results indicate that 2-hydroxy fatty acids are another putative category of root exudate signals perceived by Gigaspora species, stimulating an increase in elongated lateral branches.

Molecular dynamic simulation of dicarboxylic acid coated aqueous aerosol: structure and processing of water vapor

Organic monolayers at the surfaces of aqueous aerosols play an important role in determining the mass, heat transfer rate and surface reactivity of atmospheric aerosols. They can potentially contribute to the formation of cloud condensation nuclei (CCN) and are involved in a series of chemical reactions occurring in atmosphere. Recent studies even suggest that organic-coated interfaces could have played some role in prebiotic biochemistry and the origin of life. However, creating reproducible, well-characterized aqueous aerosol particles coated with organic films is an experimental challenge. This opens the opportunity for computer simulations and modeling of these complex structures. In this work, molecular dynamics simulation was used to probe the structure and the interfacial properties of the dicarboxylic acid coated aqueous aerosol. Low molecular weight dicarboxylic acids of various chain lengths and water solubility were chosen to coat a water droplet consisting of 2440 water molecules. For malonic acid coated aerosol, the surface acid molecules dissolved into the water core and formed an ordered structure due to the hydrophobic interactions. The acid and the water are separated inside the aerosol. For other nanoaerosols coated with low solubility acids, phase separation between water and acid molecules was observed on the surface of the particle. To study the water processing of the coated aerosols, the water vapor accommodation factors were calculated.

High dietary intake of medium-chain fatty acids during pregnancy in rats prevents later-life obesity in their offspring

We investigated the effects of dietary fatty acids of different chain lengths during pregnancy in the rat on the susceptibility of offspring to later-life obesity and the underlying mechanisms. Pregnant rats were fed three different diets: standard (STD), high medium-chain fatty acids (MCFA); and high long-chain fatty acids (LCFA). The male offspring were assigned to three groups: STD control, MCFA and LCFA according to the maternal diets and suckled by dams fed with STD during pregnancy and lactation. After weaning, the offspring were fed with STD from 3 to 8 weeks of age. At the age of 8 weeks, rats in three groups: high-fat diet (HFD) control, MCFA and LCFA were fed with HFD until 14 weeks of age in an attempt to induce obesity, and rats in the HFD control group were selected randomly from the STD control group. Body weight and body fat content were decreased in the MCFA group accompanied by down-regulated mRNA expression of fatty acid synthase and acetyl-coA carboxylase 1, and increased mRNA and protein expression of adenosine monophosphate (AMP)-activated protein kinase (AMPK), carnitine palmitoyltransferase 1 and uncoupling protein 3 compared with the corresponding controls at 3, 8 and 14 weeks of age. The results suggested that the MCFA diet during pregnancy prevented later-life obesity in the offspring when they were exposed to HFD in later life, which might be related to programming of the expression of genes involved in fatty acid metabolism.

Hoeflea anabaenae sp. nov., an epiphytic symbiont that attaches to the heterocysts of a strain of Anabaena

The heterotrophic, epiphytic, symbiotic bacterial strain WH2K(T) was previously isolated from a two-member culture in which it was attached to the heterocysts of a strain of Anabaena (SSM-00). Analysis of its 16S rRNA gene sequence demonstrated that the symbiont was most closely related to the type strain of Hoeflea marina (96.9 % similarity), which belongs to the family Phyllobacteriaceae within the order Rhizobiales of the class Alphaproteobacteria. A polyphasic taxonomic study was performed on strain WH2K(T), which consisted of irregular rods (2-5 µm long, 0.2 µm wide) that appeared to be narrower at one pole. Optimal growth was obtained in complex media with 15 g sea salts l(-1), at 18-34 °C (30 °C optimum) and at pH 6.0-8.0 (optimum pH 6.5). Unknown growth requirements were provided by small amounts of yeast extract but not by standard vitamin and trace metal solutions. Of the substrates tested, WH2K(T) was able to utilize only acetate, pyruvate, malate and fumarate. Growth was observed only under aerobic and microaerobic conditions, and nitrate was not reduced. No photosynthetic pigments were detected under any of the growth conditions tested. The predominant fatty acids were a summed feature that comprises C(18 : 1)ω7c, C(18 : 1)ω9t, C(18 : 1)ω12t or any combination of these (64.0 %) and an unidentified fatty acid of equivalent chain length 17.603 (13.5 %). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, phosphoglycolipid, unknown lipids and an unidentified aminolipid. The only respiratory ubiquinone detected was Q-10. The DNA G+C content of the strain was 58.1 mol%. The organism can form a site-specific attached symbiotic relationship with a species of Anabaena. Based on phylogenetic and phenotypic evidence, it is proposed that strain WH2K(T) be classified within a novel species of the genus Hoeflea, for which the name Hoeflea anabaenae sp. nov. is proposed. The type strain is WH2K(T) ( = CCUG 56626(T) = NRRL B-59520(T)).

Studies on the Cure Reaction and Relationship between Network Structure/Thermal Properties of Styrene Copolymers Based on Adypic/Sebacic Acid Modified Unsaturated (Epoxy) Polyesters

AbstractThe studies on the relationship between network structure/thermal properties of styrene copolymers based on adypic/sebacic acid modified unsaturated (epoxy) polyesters cured using different hardeners as well as the course of the cure reaction of polyesters with styrene have been presented. The adypic/sebacic acid modified unsaturated polyesters (UP) prepared from 4‐cyclohexene‐1,2‐dicarboxylic anhydride (THPA), maleic anhydride (MA), adypic acid (AA) or sebacic acid (SA) and ethylene glycol (EG) and their epoxy derivatives: adypic/sebacic acid modified unsaturated epoxy polyesters (UEP) were subjected to the cure process with styrene using diacyl peroxide: benzoyl peroxide (BPO) or the mixture of BPO/suitable acid anhydride: 4‐cyclohexene‐1,2‐dicarboxylic anhydride (THPA) or glutaric anhydride (GA). Thermal properties were evaluated by means of DSC, TG and DMA analyses. It was proved that studied properties were significantly depended on polyester's structure and the type of applied curing system. Generally, higher values of E'20°C, tgδmax, E”, νe, IDT, Tk for styrene copolymers based on UEP were obtained. It was connected with more cross‐linked polymer network structure due to the possible copolymerization reaction of carbon‐carbon double bonds of polyester with styrene and additional polyaddition of epoxy to anhydride groups or thermal curing of epoxy groups. The additional connections between polyester's chains led to obtain more stiff and thermal stable polymeric materials. Moreover, the increase of saturated aliphatic acid's chain length in polyester backbone caused the decrease of E'20°C, tgδmax, E”, νe, IDT, Tk values of styrene copolymers. It suggested that copolymers based on polyesters prepared from acid containing more methylene groups in their structure were characterized by more flexible polymer network due to the “laxity” effect of aliphatic chains.

PM-IRRAS studies of the adsorption and stability of organophosphonate monolayers on passivated NiTi surfaces

Alkylphosphonic acids of different alkyl chain lengths were adsorbed on electrochemically polished NiTi surfaces from ethanolic solutions. The electropolishing process led to passive films mainly composed of Ti-oxyhydroxide. The surface showed nanoscopic etching pits with a depths of about 2 nm and a diameter of about 20 nm. The interfacial binding mechanism of the phosphonic acid group to the oxyhydroxide surface and the ordering of the monolayer were spectroscopically analysed by means of infrared reflection absorption FTIR-spectroscopy with (PM-IRRAS) and without (IRRAS) photoelastic modulation. The comparison of IRRAS and PM-IRRAS data of the long chain octadecylphosphonic acid monolayer proved that the binding mechanism of the phosphonic acid group to the oxyhydroxide surface is based on a mono- or bidentate bond, which is not stable in the presence of high water activities. An alkyl chain length of 17 CH 2 groups is required for the formation of self-assembled monolayers, which are stable in aqueous environments. These long chain aliphatic organophosphonic acid monolayers were shown to inhibit anodic and cathodic surface reactions.

Development of a Fluorescence Model for the Binding of Medium- to Long-Chain Perfluoroalkyl Acids to Human Serum Albumin Through a Mechanistic Evaluation of Spectroscopic Evidence

A novel model for measuring the strength of perfluoroalkyl acid (PFAA) binding to human serum albumin (HSA) by use of the protein's native fluorescence is described. The model is derived from published properties of HSA and its interactions with other surfactants; it is consistent with these properties and experimental observations. The model's validity has been tested with both medium- to long-chain PFAAs (perfluoroheptanoate, perfluorooctanoate, perfluorononanoate, perfluorodecanoate, perfluoroundecanoate, perfluorohexanesulfonate, and perfluorooctanesulfonate) and short-chain PFAAs (perfluorohexanoate and perfluorobutanesulfonate). These experiments confirm the model as a valid description for the binding of medium- to long-chain PFAAs to HSA. Results indicate at least 2-3 PFAAs bind to each protein with affinity on the order of 10(4) M(-1). These binding strengths exhibit a dependence on protein concentration. Measured PFAA binding constants are approximately 10% of those values reported for fatty acids of similar chain length; correcting for protein concentration suggests the binding strengths may be as low as 2-3% of the corresponding fatty acids' affinities. Like fatty acids, the carboxylate PFAAs exhibit a trend of generally increasing binding strength with increased chain length. The model does not appear valid for the binding of short-chain PFAAs to HSA. Hill binding coefficients, fluorescence intensity measurements, and wavelengths of maximum emission suggest short-chain PFAAs associate with HSA differently and fail to promote the same conformational changes in the protein's tertiary structure as the medium- to long-chain PFAAs.

ChemInform Abstract: Synthesis and Evaluation of ω-Borono-α-Amino Acids as Active-Site Probes of Arginase and Nitric Oxide Synthases.

Enantiomerically pure ω-borono-α-amino acids of various chain lengths have been synthesized according to a general methodology involving condensation of alkenyl and alkynyl bromides with NiII complex of the Schiff base derived from glycine and (S)-2-[N′-(N-benzylprolyl)amino]benzophenone, hydroboration of the intermediate ω-unsaturated α-amino acids with diisopinocampheylborane, and oxidation with acetaldehyde. Some of these compounds act as potent inhibitors of rat liver and murine macrophage arginases, demonstrating that distance between the B(OH)2 and α-amino acid groups is a key determinant for their interaction with arginase. In contrast, they are without effect on neuronal and inducible NO synthases.

Naphthalene appended 2,5-diketopiperazine towards fluorometric response of dihydrogenphosphate

Naphthalene-based 2,5-diketopiperazine 1 has been synthesized in two steps with moderate yield. The compound shows water templated hydrogen bonded assemblies in the solid state and exhibits unique hydrogen bond mediated emission properties in solution. The monomer emission of 1 in CHCl3 containing 0.1% DMSO is significantly quenched in the presence of large excess of dihydrogenphosphate anion and aliphatic dicarboxylic acids of different chain lengths followed by the appearance of a new peak of moderate intensity at higher wavelength for excimer. The appearance of excimer emission of moderate intensity in presence of H2PO4 − distinguishes it from other guests in the present study.

Acyl-coenzyme A synthetases in metabolic control

The 11 long-chain (ACSL) and very long chain acyl-coenzyme A (acyl-CoA) synthetases [(ACSVL)/fatty acid transport protein] are receiving considerable attention because it has become apparent that their individual functions are not redundant. Recent studies have focused on the structure of the acyl-CoA synthetases, their post-translational modification, their ability to activate fatty acids of varying chain lengths, and their role in directing fatty acids into different metabolic pathways. An unsettled controversy focuses on the ACSVL isoforms and whether these have both enzymatic and transport functions. Another issue is whether conversion of a fatty acid to an acyl-CoA produces an increase in the AMP/ATP ratio that is sufficient to activate AMP-activated kinase. Future studies are required to determine the subcellular location of each ACSL and ACSVL isoform and the functional importance of phosphorylation and acetylation. Purification and crystallization of mammalian ACSL and ACSVL isoforms is needed to confirm the mechanism of action and discover how these enzymes differ in their affinity for fatty acids of different chain lengths. Functionally, it will be important to learn how the ACSL isoforms can direct their acyl-CoA products toward independent downstream pathways.

Structure and Morphology of Thin Films of Linear Aliphatic Polyesters Prepared by Spin-Coating

Thin films, with thicknesses from 10 to 400 nm of linear aliphatic polyesters (X, Y), based on propylenediol (X = 3) and on dicarboxylic acid of different chain length (Y = 2, 3, and 4 CH(2) units) were prepared by spin coating of CHCl(3) polymer solutions with different polymer concentrations. Morphology and structure of the spin coated thin films were investigated by atomic force microscopy (AFM) and by grazing incidence X-ray scattering techniques at small, (GISAXS) and wide angles (GIWAXS). AFM revealed a strong dewetting for all three polymers for coatings thinner than 100 nm. The polymer films are clearly semicrystalline for thicknesses higher than 50 nm. GIWAXS of the thicker films revealed their oriented crystalline nature. An edge-on-lamellae morphology is clearly shown by the AFM-phase images even for relatively thin films. SAXS with the beam parallel to the sample plane also support the presence of lamellae perpendicular to the substrate. The use of a mu-beam helped to interpret the GIWAXS patterns and allowed to obtain oriented WAXS patterns from melt solidified filaments. Thus, a crystal chain packing is proposed for the three polymers and consequently the indexing of the observed reflections. Accordingly, the polymer chains lie parallel to the substrate being the bc plane of the monoclinic crystal unit cell parallel to the substrate.

A coarse-grained model for amorphous and crystalline fatty acids.

Fatty acids constitute one of the main components of the lipid lamellae in the top layer of the skin, known as the stratum corneum, which acts as a barrier to foreign substances entering the body and to water leaving the body. To better understand the mechanics of the skin, a molecular-level understanding of the structure of the lamellae needs to be investigated. As a first step toward this goal, the current work involves the development of a coarse-grained model for fatty acids in an amorphous and a crystalline state. In order to retain the structural details of the atomistic molecules, radial distribution functions have been used to provide target data against which the coarse-grained force field is optimized. The optimization was achieved using the method developed by Reith, Putz, and Muller-Plathe with a damping factor introduced into the updating scheme to facilitate the convergence against the crystalline radial distribution functions. Using this approach, a transferable force field has been developed for both crystalline and amorphous systems that can be used to describe fatty acids of different chain lengths. We are unaware of any other coarse-grained model in the literature that has been developed to study solid phases. Additionally, the amorphous force field has been shown to accurately model mixtures of different free fatty acids based on the potentials derived from pure lipid systems.

Enzymatic synthesis of short‐chain esters in n‐hexane and supercritical carbon dioxide: Effect of the acid chain length

AbstractEnzymatic synthesis is the preferred way to produce so‐called “natural products.” Hydrolases have been used for short‐chain ester synthesis. These esters present a pleasant flavor and they have a lot of applications in different industries. Novozym 435 from Candida antarctica (EC 3.1.1.3, triacylglycerol lipase) was used for hexyl ester synthesis in n‐hexane and supercritical carbon dioxide (SCCO2). Direct esterification provided higher yields than transesterification for the synthesis of esters. Several carboxylic acids of different chain lengths were tested for the esterification reactions: acetic, propionic, butyric, caproic and caprylic acids. The reactions were carried out at 40°C and the amount of enzyme used was 13.8 g/mol alcohol. Substrates were added at equimolar concentrations, with sufficient stirring to avoid external diffusion control. Different substrate concentrations up to 1.5 M were used. The working pressure was 14 MPa in the case of SCCO2 and atmospheric pressure in the case of organic solvent. The results in both solvents show that the reaction rate increases with the chain length of the acid, but the final yields were similar. However, some of the reactions prove to be faster in SCCO2, except for hexyl acetate and propionate synthesis, in which acetic and propionic acid presented a lower solubility in SCCO2 due to its high polarity. Moreover, an acetic acid concentration of 1.5 M brought about a strong inhibition of the enzyme activity.

Effects of Administration of Three Different By-Pass Lipids on Growth Performance, Rumen Activity and Feeding Behaviour of Beef Cattle

A study was carried out on beef cattle to compare three different by-pass lipids administration in relation to their intake, performance, bunk behaviour and rumen fermentation characteristics. Ninety-six Charolaise males were subdivided into three groups. Each group was fed a specific diet including differentiated sources of rumen by-pass fats. The first group received 500 g/head/day of calcium salts (CaS), the second and the third received 420 g/head/day of hydrogenated fatty acids (HF) and triglycerides (AL), respectively. The three by-pass fats differ in fatty acids composition, chain length and mean particle size. AL group had average daily gain significantly greater (P=0.0005) than animals fed calcium soaps. No difference was observed between AL and HF groups (P=0.08) and between HF and CaS groups. Final body weights of AL animals were significantly higher (P=0.005) than CaS group. There were no differences between AL group and HF group and between HF group and CaS group. Average dry matter intake (DMI) was higher (P<0.05) in AL and HF groups compared with CaS group. Feed conversion rate was better for AL and CaS groups (P<0.05) compared with HF group. Evaluating their behaviours in approaching feed, the animals seemed to prefer hydrogenated fats flavour as regard to calcium soaps. No differences were highlighted in ruminal pH and ruminal volatile fatty acids composition among the three groups. When high dosage of fat is included into a beef cattle diet, the administration of hydrogenated triglycerides, characterized by a pleasant flavour and a small mean particle size, is likely to be more suitable than adding calcium soaps or hydrogenated free fatty acids, probably thanks to its higher DMI and feed conversion rate, respectively. With regard to the latter higher rate, it could be only supposed that it is related to the smaller mean particle size of hydrogenated triglycerides.

Activation of Peroxisome Proliferator-Activated Receptor γ (PPARγ) by Nitroalkene Fatty Acids: Importance of Nitration Position and Degree of Unsaturation

Nitroalkene fatty acids are potent endogenous ligand activators of PPARgamma-dependent transcription. Previous studies with the naturally occurring regioisomers of nitrolinoleic acid revealed that the isomers are not equivalent with respect to PPARgamma activation. To gain further insight into the structure-activity relationships between nitroalkenes and PPARgamma, we examined additional naturally occurring nitroalkenes derived from oleic acid, 9-nitrooleic acid (E-9-NO2-18:1 [1]) and 10-nitrooleic acid (E-10-NO2-18:1 [2]), and several synthetic nitrated enoic fatty acids of variable carbon chain length, double bonds, and nitration site. At submicromolar concentrations, E-12-NO2 derivatives were considerably more potent than isomers nitrated at carbons 5, 6, 9, 10, and 13, and chain length (16 versus 18) or number of double bonds (1 versus 2) was of little consequence for PPARgamma activation. Interestingly, at higher concentrations (>2 microM) the nitrated enoic fatty acids (E-9-NO2-18:1 [1], E-9-NO2-16:1 [3], E-10-NO2-18:1 [2], and E-12-NO2-18:1 [7]) deviated significantly from the saturable pattern of PPARgamma activation observed for nitrated 1,4-dienoic fatty acids (E-9-NO2-18:2, E-10-NO2-18:2, E-12-NO2-18:2, and E-13-NO2-18:2).

The Plastidic Bile Acid Transporter 5 Is Required for the Biosynthesis of Methionine-Derived Glucosinolates inArabidopsis thaliana

Aliphatic glucosinolate biosynthesis is highly compartmentalized, requiring import of 2-keto acids or amino acids into chloroplasts for side chain elongation and export of the resulting compounds into the cytosol for conversion into glucosinolate. Aliphatic glucosinolate biosynthesis in Arabidopsis thaliana is regulated by three R2R3-MYB transcription factors, the major player being High Aliphatic Glucosinolate 1 (HAG1/MYB28). Here, we show that BAT5, which belongs to the putative bile acid transporter family, is the only member of this family that is transactivated by HAG1/MYB28, HAG2/MYB76, and HAG3/MYB29. Furthermore, two isopropylmalate isomerases genes, IPMI1 and IPMI2, and the isopropylmalate dehydrogenase gene, IPMDH1, were identified as targets of HAG1/MYB28 and the corresponding proteins localized to plastids, suggesting a role in plastidic chain elongation reactions. The BAT proteins also localized to plastids; however, only mutants defective in BAT5 function contained strongly reduced levels of aliphatic glucosinolates. The bat5 mutant chemotype was rescued by induced overexpression of BAT5. Feeding experiments using 2-keto acids and amino acids of different chain length suggest that BAT5 is a plastidic transporter of (chain-elongated) 2-keto acids. Mechanical stimuli and methyl jasmonate transiently induced BAT5 expression in inflorescences and leaves. Thus, BAT5 was identified as the first transporter component of the aliphatic glucosinolate biosynthetic pathway.

Triphenylamine-Based Receptors in Selective Recognition of Dicarboxylic Acids

New triphenylamine-based chemosensors for selective recognition of dicarboxylic acids have been designed and synthesized. They are variants of previously synthesized chemosensors, offering different possibilities for selective recognition of dicarboxylic acids. Theoretical calculations by density functional theory and time dependent density functional theory have been carried out on these as well as on one of the previously reported systems and on complexes formed by the triphenylamine based chemosensors and aliphatic dicarboxylic acids of different chain-lengths. Carboxylic acid binding takes place through charge-neutral pyridyl amide receptor sites with concomitant quenching of fluorescence of the triphenylamine moiety. The theoretical results are consistent with the experimental and correlation is found between the calculated binding energies and the experimental binding constants.