THE METABOLISM OF AROMATIC COMPOUNDS WITH DIFFERENT SIDE CHAINS BY A PSEUDOMONAS

1. By means of 14C tracer experiments and isotope competition experiments the roles of d-tyrosine, p-hydroxyphenylpyruvic acid, p-hydroxyphenylacetic acid, phenylacetic acid, homogentisic acid and homoarbutin (2-methylquinol 4-β-d-glucoside) in the biosynthesis of plastoquinones, tocopherols and α-tocopherolquinone by maize shoots was investigated. It was established that d-tyrosine, p-hydroxyphenylpyruvic acid and homogentisic acid can all be utilized for this purpose, whereas p-hydroxyphenylacetic acid, phenylacetic acid and homoarbutin cannot. Studies on the mode of incorporation of d-tyrosine, p-hydroxyphenylpyruvic acid and homogentisic acid showed that their nuclear carbon atoms and the side-chain carbon atom adjacent to the nucleus give rise (as a C6-C1 unit) to the p-benzoquinone rings and nuclear methyl groups (one in each case) of plastoquinone-9 and α-tocopherolquinone and the aromatic nuclei and nuclear methyl groups (one in each case) of γ-tocopherol and α-tocopherol. 2. By using [14C]-homogentisic acid it has been shown that homogentisic acid is also a precursor of plastoquinone, tocopherols and α-tocopherolquinone in the higher plants Lactuca sativa and Rumex sanguineus, the green algae Chlorella pyrenoidosa and Euglena gracilis and the blue–green alga Anacystis nidulans.

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STUDIES OF LIGNIN BIOSYNTHESIS USING ISOTOPIC CARBON: VI. FORMATION OF THE SIDE CHAIN OF THE PHENYLPROPANE MONOMER

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o58-111 ◽

1958 ◽

Vol 36 (10) ◽

pp. 1037-1045 ◽

Cited By ~ 22

Author(s):

D. Wright ◽

Stewart A. Brown ◽

A. C. Neish

Keyword(s):

Aromatic Compounds ◽

Mandelic Acid ◽

Enzyme System ◽

Lignin Biosynthesis ◽

Side Chain ◽

Side Chains ◽

Phenyllactic Acid ◽

Marked Preference ◽

Varying Length

A number of aromatic compounds having carbon side chains of varying length and substitution have been studied as lignin precursors. p-Hydroxybenzaldehyde was poorly utilized, indicating that the formation of C6,C3 units from a condensation of C6,C1, and C2 fragments is of very limited significance. The C6,C2 compound, mandelic acid, was not converted to lignin. DL-Phenyllactic acid was incorporated into lignin with much lower dilution than either DL-erythro- or DL-threo-phenylglyceric acids, and with appreciably lower dilution than DL-phenylhydracrylic acid, supporting the concept that lignin monomers are formed via 2-hydroxylated phenylpropane intermediates. Wheat utilized the D-form of phenylalanine less readily than the L-form. Although three monocotyledons tested could utilize (+)- and (−)-phenyllactic acid to a comparable degree, two dicotyledons showed a marked preference for the (−)-form, suggesting that in dicotyledons the enzyme system specific for the (−)-form is predominant.

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Effect of electron-donating substituent groups on aromatic ring on photoluminescence properties of complexes of benzoic acid-functionalized polysulfone with Eu(iii) ions

Physical Chemistry Chemical Physics ◽

10.1039/c5cp03300d ◽

2015 ◽

Vol 17 (38) ◽

pp. 25322-25332 ◽

Cited By ~ 16

Author(s):

Baojiao Gao ◽

Lulu Chen ◽

Tao Chen

Keyword(s):

Benzoic Acid ◽

Aromatic Ring ◽

Molecular Design ◽

Hydroxybenzoic Acid ◽

Side Chains ◽

Photoluminescence Properties ◽

Polymer Reactions ◽

Methoxybenzoic Acid

By molecular design and via polymer reactions, methoxybenzoic acid (MOBA) and hydroxybenzoic acid (HBA) were bonded onto the side chains of polysulfone (PSF) for preparing two benzoic acid-functionalized PSFs, PSF-MOBA and PSF-HBA, respectively.

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STUDIES OF LIGNIN BIOSYNTHESIS USING ISOTOPIC CARBON: VI. FORMATION OF THE SIDE CHAIN OF THE PHENYLPROPANE MONOMER

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y58-111 ◽

1958 ◽

Vol 36 (1) ◽

pp. 1037-1045 ◽

Cited By ~ 6

Author(s):

D. Wright ◽

Stewart A. Brown ◽

A. C. Neish

Keyword(s):

Aromatic Compounds ◽

Mandelic Acid ◽

Enzyme System ◽

Lignin Biosynthesis ◽

Side Chain ◽

Side Chains ◽

Phenyllactic Acid ◽

Marked Preference ◽

Varying Length

A number of aromatic compounds having carbon side chains of varying length and substitution have been studied as lignin precursors. p-Hydroxybenzaldehyde was poorly utilized, indicating that the formation of C6,C3 units from a condensation of C6,C1, and C2 fragments is of very limited significance. The C6,C2 compound, mandelic acid, was not converted to lignin. DL-Phenyllactic acid was incorporated into lignin with much lower dilution than either DL-erythro- or DL-threo-phenylglyceric acids, and with appreciably lower dilution than DL-phenylhydracrylic acid, supporting the concept that lignin monomers are formed via 2-hydroxylated phenylpropane intermediates. Wheat utilized the D-form of phenylalanine less readily than the L-form. Although three monocotyledons tested could utilize (+)- and (−)-phenyllactic acid to a comparable degree, two dicotyledons showed a marked preference for the (−)-form, suggesting that in dicotyledons the enzyme system specific for the (−)-form is predominant.

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Degradation of Aromatic Compounds in Plants Grown under Aseptic Conditions

Zeitschrift für Naturforschung C ◽

10.1515/znc-2005-1-218 ◽

2005 ◽

Vol 60 (1-2) ◽

pp. 97-102 ◽

Cited By ~ 8

Author(s):

Teimuraz Mithaishvili ◽

René Scalla ◽

Devi Ugrekhelidze ◽

Benedict Tsereteli ◽

Tinatin Sadunishvili ◽

...

Keyword(s):

Aromatic Ring ◽

Aromatic Compounds ◽

Higher Plants ◽

Environmental Pollutants ◽

Krebs Cycle ◽

Oxidative Degradation ◽

Transformation Products ◽

Ring Cleavage ◽

Intermediate Transformation ◽

Aromatic Ring Cleavage

The aim of the work is to investigate the ability of higher plants to absorb and detoxify environmental pollutants - aromatic compounds via aromatic ring cleavage. Transformation of 14C specifically labelled benzene derivatives, [1-6-14C]-nitrobenzene, [1-6-14C]-aniline, [1-14C]- and [7-14C]-benzoic acid, in axenic seedlings of maize (Zea mays L.), kidney bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) and pumpkin (Cucurbita pepo L.) were studied. After penetration in plants, the above xenobiotics are transformed by oxidative or reductive reactions, conjugation with cell endogenous compounds, and binding to biopolymers. The initial stage of oxidative degradation consists in hydroxylation reactions. The aromatic ring can then be cleaved and degraded into organic acids of the Krebs cycle. Ring cleavage is accompanied by 14CO2 evolution. Aromatic ring cleavage in plants has thus been demonstrated for different xenobiotics carrying different substitutions on their benzene ring. Conjugation with low molecular peptides is the main pathway of aromatic xenobiotics detoxification. Peptide conjugates are formed both by the initial xenobiotics (except nitrobenzene) and by intermediate transformation products. The chemical nature of the radioactive fragment and the amino acid composition of peptides participating in conjugation were identified.

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Influence of Flexible Side-Chains on the Breathing Phase Transition of Pillared Layer MOFs: A Force Field Investigation

10.26434/chemrxiv.11720679.v1 ◽

2020 ◽

Author(s):

Julian Keupp ◽

Johannes P. Dürholt ◽

Rochus Schmid

Keyword(s):

First Principles ◽

Good Accuracy ◽

Field Investigation ◽

Square Lattice ◽

Side Chain ◽

Second Step ◽

Side Chains ◽

Dynamics Simulations ◽

Complex Phenomena ◽

Closed Pore

The prototypical pillared layer MOFs, formed by a square lattice of paddle- wheel units and connected by dinitrogen pillars, can undergo a breathing phase transition by a “wine-rack” type motion of the square lattice. We studied this not yet fully understood behavior using an accurate first principles parameterized force field (MOF-FF) for larger nanocrystallites on the example of Zn 2 (bdc) 2 (dabco) [bdc: benzenedicarboxylate, dabco: (1,4-diazabicyclo[2.2.2]octane)] and found clear indi- cations for an interface between a closed and an open pore phase traveling through the system during the phase transformation [Adv. Theory Simul. 2019, 2, 11]. In conventional simulations in small supercells this mechanism is prevented by periodic boundary conditions (PBC), enforcing a synchronous transformation of the entire crystal. Here, we extend this investigation to pillared layer MOFs with flexible side-chains, attached to the linker. Such functionalized (fu-)MOFs are experimen- tally known to have different properties with the side-chains acting as fixed guest molecules. First, in order to extend the parameterization for such flexible groups, 1a new parametrization strategy for MOF-FF had to be developed, using a multi- structure force based fit method. The resulting parametrization for a library of fu-MOFs is then validated with respect to a set of reference systems and shows very good accuracy. In the second step, a series of fu-MOFs with increasing side-chain length is studied with respect to the influence of the side-chains on the breathing behavior. For small supercells in PBC a systematic trend of the closed pore volume with the chain length is observed. However, for a nanocrystallite model a distinct interface between a closed and an open pore phase is visible only for the short chain length, whereas for longer chains the interface broadens and a nearly concerted trans- formation is observed. Only by molecular dynamics simulations using accurate force fields such complex phenomena can be studied on a molecular level.

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Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

Polymers ◽

10.3390/polym13111789 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1789

Author(s):

Dmitry Tolmachev ◽

George Mamistvalov ◽

Natalia Lukasheva ◽

Sergey Larin ◽

Mikko Karttunen

Keyword(s):

Glutamic Acid ◽

Chain Length ◽

Chemical Structure ◽

Side Chain ◽

Side Chains ◽

Side Chain Length ◽

Polyelectrolyte Brushes ◽

Grafting Density ◽

The Difference ◽

Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

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Unusual Structural Features in the Adduct of Dirhodium Tetraacetate with Lysozyme

International Journal of Molecular Sciences ◽

10.3390/ijms22031496 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1496

Author(s):

Domenico Loreto ◽

Giarita Ferraro ◽

Antonello Merlino

Keyword(s):

Anticancer Agents ◽

Structural Features ◽

Side Chain ◽

Side Chains ◽

Valuable Insight ◽

Experimental Conditions ◽

Egg White Lysozyme ◽

Potential Applications ◽

Model Protein ◽

Hen Egg White

The structures of the adducts formed upon reaction of the cytotoxic paddlewheel dirhodium complex [Rh2(μ-O2CCH3)4] with the model protein hen egg white lysozyme (HEWL) under different experimental conditions are reported. Results indicate that [Rh2(μ-O2CCH3)4] extensively reacts with HEWL:it in part breaks down, at variance with what happens in reactions with other proteins. A Rh center coordinates the side chains of Arg14 and His15. Dimeric Rh–Rh units with Rh–Rh distances between 2.3 and 2.5 Å are bound to the side chains of Asp18, Asp101, Asn93, and Lys96, while a dirhodium unit with a Rh–Rh distance of 3.2–3.4 Å binds the C-terminal carboxylate and the side chain of Lys13 at the interface between two symmetry-related molecules. An additional monometallic fragment binds the side chain of Lys33. These data, which are supported by replicated structural determinations, shed light on the reactivity of dirhodium tetracarboxylates with proteins, providing useful information for the design of new Rh-containing biomaterials with an array of potential applications in the field of catalysis or of medicinal chemistry and valuable insight into the mechanism of action of these potential anticancer agents.

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Synthesis of New Derivatives of BEDT-TTF: Installation of Alkyl, Ethynyl, and Metal-Binding Side Chains and Formation of Tris(BEDT-TTF) Systems

Magnetochemistry ◽

10.3390/magnetochemistry7080110 ◽

2021 ◽

Vol 7 (8) ◽

pp. 110

Author(s):

Songjie Yang ◽

Matteo Zecchini ◽

Andrew Brooks ◽

Sara Krivickas ◽

Desiree Dalligos ◽

...

Keyword(s):

Metal Binding ◽

Tricarboxylic Acid ◽

Metal Salts ◽

Side Chain ◽

Side Chains ◽

Ethynyl Group ◽

X Ray ◽

Transition Metal Salts ◽

Alkyl Side Chains ◽

Derivatives Of

The syntheses of new BEDT-TTF derivatives are described. These comprise BEDT-TTF with one ethynyl group (HC≡C-), with two (n-heptyl) or four (n-butyl) alkyl side chains, with two trans acetal (-CH(OMe)2) groups, with two trans aminomethyl (-CH2NH2) groups, and with an iminodiacetate (-CH2N(CH2CO2−)2 side chain. Three transition metal salts have been prepared from the latter donor, and their magnetic properties are reported. Three tris-donor systems are reported bearing three BEDT-TTF derivatives with ester links to a core derived from benzene-1,3,5-tricarboxylic acid. The stereochemistry and molecular structure of the donors are discussed. X-ray crystal structures of two BEDT-TTF donors are reported: one with two CH(OMe)2 groups and with one a -CH2N(CH2CO2Me)2 side chain.

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Current Understanding of the Structure, Stability and Dynamic Properties of Amyloid Fibrils

International Journal of Molecular Sciences ◽

10.3390/ijms22094349 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4349

Author(s):

Eri Chatani ◽

Keisuke Yuzu ◽

Yumiko Ohhashi ◽

Yuji Goto

Keyword(s):

Amyloid Fibrils ◽

Polypeptide Chain ◽

Dynamic Properties ◽

Protein Molecule ◽

Side Chain ◽

Structure Stability ◽

Side Chains ◽

Precise Control ◽

Functional Amyloids ◽

Structural Architecture

Amyloid fibrils are supramolecular protein assemblies represented by a cross-β structure and fibrous morphology, whose structural architecture has been previously investigated. While amyloid fibrils are basically a main-chain-dominated structure consisting of a backbone of hydrogen bonds, side-chain interactions also play an important role in determining their detailed structures and physicochemical properties. In amyloid fibrils comprising short peptide segments, a steric zipper where a pair of β-sheets with side chains interdigitate tightly is found as a fundamental motif. In amyloid fibrils comprising longer polypeptides, each polypeptide chain folds into a planar structure composed of several β-strands linked by turns or loops, and the steric zippers are formed locally to stabilize the structure. Multiple segments capable of forming steric zippers are contained within a single protein molecule in many cases, and polymorphism appears as a result of the diverse regions and counterparts of the steric zippers. Furthermore, the β-solenoid structure, where the polypeptide chain folds in a solenoid shape with side chains packed inside, is recognized as another important amyloid motif. While side-chain interactions are primarily achieved by non-polar residues in disease-related amyloid fibrils, the participation of hydrophilic and charged residues is prominent in functional amyloids, which often leads to spatiotemporally controlled fibrillation, high reversibility, and the formation of labile amyloids with kinked backbone topology. Achieving precise control of the side-chain interactions within amyloid structures will open up a new horizon for designing useful amyloid-based nanomaterials.

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