- Snapshots of the Catalytic Cycle of an O2, Pyridoxal Phosphate-Dependent Hydroxylase
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Enzymes that catalyze hydroxylation of unactivated carbons normally contain heme and nonheme iron cofactors. By contrast, how a pyridoxal phosphate (PLP)-dependent enzyme could catalyze such a hydroxylation was unknown. Here, we investigate RohP, a PLP-dependent enzyme that converts l-arginine to (S)-4-hydroxy-2-ketoarginine. We determine that the RohP reaction consumes oxygen with stoichiometric release of H2O2. To understand this unusual chemistry, we obtain ～1.5 ? resolution structures that capture intermediates along the catalytic cycle. Our data suggest that RohP carries out a four-electron oxidation and a stereospecific alkene hydration to give the (S)-configured product. Together with our earlier studies on an O2, PLP-dependent l-arginine oxidase, our work suggests that there is a shared pathway leading to both oxidized and hydroxylated products from l-arginine.
- Hedges, Jason B.,Kuatsjah, Eugene,Du, Yi-Ling,Eltis, Lindsay D.,Ryan, Katherine S.
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- A common origin for guanidinobutanoate starter units in antifungal natural products
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Keeping it basic: Arginine provides the exotic 4-guanidinobutanoate starter unit for two different types of zwitterionic polyketide (an example for one type is shown in the picture) produced by the same Streptomyces bacterium. The three-step precursor pathway is initiated by a remarkable decarboxylating monooxygenase with high specificity for arginine. Copyright
- Hong, Hui,Fill, Taicia,Leadlay, Peter F.
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supporting information
p. 13096 - 13099
(2014/01/06)
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- Deposition of new thia-containing Schiff-base iron (III) complexes onto carbon nanotube-modified glassy carbon electrodes as a biosensor for electrooxidation and determination of amino acids
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Multiwall carbon nanotubes (MWCNTs) were used as an immobilization matrix to incorporate an Fe (III)-Schiff base complex as an electron-transfer mediator onto a glassy carbon electrode surface. First, the preheated glassy carbon was subjected to abrasive immobilization of MWCNTs by gently rubbing the electrode surface on filter paper supporting the carbon nanotubes. Second, the electrode surface was modified by casting 100 μL of an Fe (III)-complex solution (0.01 M in ACN). The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and nearly reversible reductive oxidation redox systems with surface confined characteristics. Combinations of unique electronic and electrocatalytic properties of MWCNTs and Fe (III)-Schiff base complexes resulted in a remarkable synergistic augmentation of the response. The electrochemical behavior and stability of the modified electrode in aqueous solutions at pH 1-9 were characterized by cyclic voltammetry. The apparent electron transfer rate constant (Ks) and transfer coefficient (a) were determined by cyclic voltammetry and were approximately 7 s-1 and 0.55, respectively. The modified electrodes showed excellent catalytic activity towards the oxidation of amino acids at an unusually positive potential in acidic solution. They also displayed inherent stability at a wide pH range, fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of amino acids that decreased the effect of interferences in analysis. The linear concentration range, limits of detection (LOD), limits of quantization (LOQ) and relative standard deviation of the proposed sensor for the amino acid detection were 1-55,000, 1.10-13.70, 2.79-27.14 and 1.30-5.11, respectively.
- Saghatforoush, Lotfali,Hasanzadeh, Mohammad,Shadjou, Nasrin,Khalilzadeh, Balal
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experimental part
p. 1051 - 1061
(2011/04/16)
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- Structural and functional characterization of plant aminoaldehyde dehydrogenase from pisum sativum with a broad specificity for natural and synthetic aminoaldehydes
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Aminoaldehyde dehydrogenases (AMADHs, EC 1.2.1.19) belong to the large aldehyde dehydrogenase (ALDH) superfamily, namely, the ALDH9 family. They oxidize polyamine-derived ω-aminoaldehydes to the corresponding ω-amino acids. Here, we report the first X-ray structures of plant AMADHs: two isoenzymes, PsAMADH1 and PsAMADH2, from Pisum sativum in complex with β-nicotinamide adenine dinucleotide (NAD+) at 2.4 and 2.15 A resolution, respectively. Both recombinant proteins are dimeric and, similarly to other ALDHs, each monomer is composed of an oligomerization domain, a coenzyme binding domain and a catalytic domain. Each subunit binds NAD+ as a coenzyme, contains a solvent-accessible C-terminal peroxisomal targeting signal (type 1) and a cation bound in the cavity close to the NAD+ binding site. While the NAD+ binding mode is classical for PsAMADH2, that for PsAMADH1 is unusual among ALDHs. A glycerol molecule occupies the substrate binding site and mimics a bound substrate. Structural analysis and substrate specificity study of both isoenzymes in combination with data published previously on other ALDH9 family members show that the established categorization of such enzymes into distinct groups based on substrate specificity is no more appropriate, because many of them seem capable of oxidizing a large spectrum of aminoaldehyde substrates. PsAMADH1 and PsAMADH2 can oxidize N,N,N-trimethyl-4-aminobutyraldehyde into γ-butyrobetaine, which is the carnitine precursor in animal cells. This activity highly suggests that in addition to their contribution to the formation of compatible osmolytes such as glycine betaine, β-alanine betaine and γ-aminobutyric acid, AMADHs might participate in carnitine biosynthesis in plants.
- Tylichova, Martina,Kopecny, David,Morera, Solange,Briozzo, Pierre,Lenobel, Rene,Snegaroff, Jacques,Sebela, Marek
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experimental part
p. 870 - 882
(2011/04/24)
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- Wrinkle-care product
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A wrinkle-care product, an aging-preventive cosmetic and a skin cosmetic each comprising a guanidine derivative of formula (I) or an acid addition salt thereof: STR1 wherein R1 represents a hydrogen atom, a lower alkyl group or --(AO)m --(BO)n --D--E ?wherein A and B may be the same or different and each represents an alkylene group having 2 to 8 carbon atoms; D represents a binding hand, --CO--, or an unsubstituted or substituted alkylene group having 1 to 6 carbon atoms; E represents a hydrogen atom, a lower alkyl group, an aralkyl group or an unsubstituted or substituted aryl group; m is a number of from 1 to 6; and n is a number of from 0 to 6!; k is a number of from 1 to 10; and G represents a hydrogen atom, a hydroxyl group, a carboxyl group, a sulfonate group or a phosphate group. These products are excellent in the effects of inhibiting wrinkling and smoothing wrinkles without damaging the physiological conditions of the skin.
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- A Facile Conversion of Amino Acids to Guanidino Acids
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The conversion of amino acids to guanidino acids by the action of aminoiminomethanesulfonic acids (2a-c) is reported.Compounds 2a-c were synthesized by peracetic acid oxidation of the corresponding thioureas.
- Miller, Audrey E.,Bischoff, Judith J.
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p. 777 - 779
(2007/10/02)
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- Methods and compositions for inducing resistance to bacterial infections
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A variety of substances are reported which alter host resistance to cocci and bacilli bacterial infections. Nevertheless, because of the extreme difficulty of total eradication, and the frequent reappearance of the same strains, even after their apparently successful elimination, there is a continuing need for drugs for the treatment of coccic infections. Certain guanidinoacylhistidines are effective in inducing resistance to infections due to cocci and bacilli.
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