Über den Ersatz positiven Wasserstoffs durch Halogen (I. Mitteil.)

Straus, Fritz; Kollek, Leo; Heyn, Walther

doi:10.1002/cber.19300630739

Cited by 125 publications

(28 citation statements)

References 16 publications

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“…The inhibitor was synthesized by a literature procedure (26). Crystals of inactivated CaaD were obtained from 2 l of hanging drops consisting of equal amounts of protein solution (8 mg/ml) and well solution containing 22% (w/v) polyethylene glycol 4000 as precipitant, 100 mM sodium acetate buffer, pH 4.8, 0.15 M ammonium acetate.…”

Section: Methodsmentioning

confidence: 99%

The X-ray Structure of trans-3-Chloroacrylic Acid Dehalogenase Reveals a Novel Hydration Mechanism in the Tautomerase Superfamily

Jong

Brugman

Poelarends

et al. 2004

Journal of Biological Chemistry

134

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Isomer-specific 3-chloroacrylic acid dehalogenases function in the bacterial degradation of 1,3-dichloropropene, a compound used in agriculture to kill plant-parasitic nematodes. The crystal structure of the heterohexameric trans-3-chloroacrylic acid dehalogenase (CaaD) from Pseudomonas pavonaceae 170 inactivated by 3-bromopropiolate shows that Glu-52 in the ␣-subunit is positioned to function as the water-activating base for the addition of a hydroxyl group to C-3 of 3-chloroacrylate and 3-bromopropiolate, whereas the nearby Pro-1 in the ␤-subunit is positioned to provide a proton to C-2. Two arginine residues, ␣Arg-8 and ␣Arg-11, interact with the C-1 carboxylate groups, thereby polarizing the ␣,␤-unsaturated acids. The reaction with 3-chloroacrylate results in the production of an unstable halohydrin, 3-chloro-3-hydroxypropanoate, which decomposes into the products malonate semialdehyde and HCl. In the inactivation mechanism, however, malonyl bromide is produced, which irreversibly alkylates the ␤Pro-1. CaaD is related to 4-oxalocrotonate tautomerase, with which it shares an N-terminal proline. However, in 4-oxalocrotonate tautomerase, Pro-1 functions as a base participating in proton transfer within a hydrophobic active site, whereas in CaaD, the acidic proline is stabilized in a hydrophilic active site. The altered active site environment of CaaD thus facilitates a previously unknown reaction in the tautomerase superfamily, the hydration of the ␣,␤-unsaturated bonds of trans-3-chloroacrylate and 3-bromopropiolate. The mechanism for these hydration reactions represents a novel catalytic strategy that results in carbon-halogen bond cleavage.Dehalogenases are enzymes that cleave carbon-halogen bonds. They are found in various bacteria, allowing them to use halogenated hydrocarbons as growth substrates (1, 2). Detailed three-dimensional structural information is available for dehalogenases such as haloalkane dehalogenase, 2-haloacid dehalogenase, and haloalcohol dehalogenase, which catalyze the cofactor-independent cleavage of the covalent bond between a halogen and an sp 3 -hybridized carbon atom by substitution mechanisms (3-5). In addition, several cofactor-dependent dehalogenases have been characterized that cleave the bond between a halogen and an sp 2 -hybridized carbon atom. Examples include heme-dependent reductive dehalogenases (6, 7) and the 4-chlorobenzoyl-CoA dehalogenases (8). In contrast, cofactorindependent dehalogenases that cleave the bond between a halogen and an sp 2 -hybridized carbon atom have only recently been discovered (9, 10).The 3-chloroacrylic acid dehalogenases from Pseudomonas pavonaceae 170 represent cofactor-independent dehalogenases that catalyze the cleavage of vinylic carbon-halogen bonds, in which the halogen is bound to an sp 2 -hybridized carbon atom (9 -11). They are part of a multienzyme degradation route for the cis-and trans-isomers of 1,3-dichloropropene (DCP).1 Cisand trans-DCP are components of the commercially produced fumigants Shell D-D and Telone II, which are us...

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Section: Methodsmentioning

confidence: 99%

The X-ray Structure of trans-3-Chloroacrylic Acid Dehalogenase Reveals a Novel Hydration Mechanism in the Tautomerase Superfamily

Jong

Brugman

Poelarends

et al. 2004

Journal of Biological Chemistry

134

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“…Due to the small vapor pressure of C 5 Br 6 , 40 only TRPES spectra with a low count rate were recorded (see ESI, † Section 5). Nevertheless, they evinced the same features as do the spectra of C 5 Cl 6 .…”

Section: Time Resolved Photoelectron Spectroscopymentioning

confidence: 99%

“…The synthesis of C 5 Br 6 was adapted from the literature. 40 A 13 C-NMR spectrum is depicted in Fig. S1 in the ESI.…”

Section: Sample Preparationmentioning

confidence: 99%

Ultrafast photoinduced dynamics of halogenated cyclopentadienes: observation of geminate charge-transfer complexes in solution

Wolf

Schalk

Radloff

et al. 2013

Phys. Chem. Chem. Phys.

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aThe photoinduced dynamics of the fully halogenated cyclopentadienes C 5 Cl 6 and C 5 Br 6 have been investigated in solution and gas phase by femtosecond time-resolved spectroscopy. Both in solution and in gas phase, homolytic dissociation into a halogen radical and a C 5 X 5 (X = Cl, Br) radical was observed.In liquid phase, solvent-dependent formation of charge transfer complexes between geminate radicals was observed for the first time. These complexes were found to be surprisingly stable and offered the opportunity to follow the dynamics of specific radical pairs. In the case of C 5 Cl 6 in trichloroethanol, a reaction of the chlorine radical with molecules from the solvent cage was observed.

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“…Cyclopentadiene was obtained by cracking dicyclopentadiene over paraffin oil. Hexabromocyclopentadiene was synthesized by a published protocol [16]. The full-length 1E9 IgG [17] and its recombinant Fab fragment [10] were prepared and purified as described previously.…”

Section: Experimental Partmentioning

confidence: 99%

Steric and Electronic Effects on an Antibody‐Catalyzed Diels–Alder Reaction

Gozin

Hilvert

2002

Helvetica Chimica Acta

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Dedicated to Dieter Seebach on the occasion of his 65th birthday A series of substituted thiophene dioxides was tested as diene substrates for the antibody 1E9, which was elicited with a hexachloronorbornene derivative and normally catalyzes the inverse electron-demand Diels ± Alder reaction between 2,3,4,5-tetrachlorothiophene dioxide (TCTD) and N-ethylmaleimide (NEM). Previous structural and computational studies had suggested that the catalytic efficiency of this system derives in part from a very snug fit between the apolar active site and the transition state of this reaction. Nevertheless, replacing all the Cl-atoms in the hapten with Br-atoms leads to no loss in affinity (K d 0.1 nm), indicating substantial conformational flexibility in the residues that line the binding pocket. Consistent with this observation, the 2,3,4,5-tetrabromothiophene dioxide is a good substrate for the antibody (k cat 1.8 min À1, K NEM 14 mm), despite being considerably larger than TCTD. In contrast, normal electron-demand Diels ± Alder reactions between NEM and unsubstituted thiophene dioxide or 2,3,4,5-tetramethylthiophene dioxide, which are much smaller or nearly isosteric with TCTD, respectively, are not detectably accelerated. These results show that the electronic properties of the 1E9 active site are optimized to a remarkable degree for the inverse electron-demand Diels ± Alder reaction for which it was designed. Indeed, they appear to play a more important role in catalysis than simple proximity effects.

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Über den Ersatz positiven Wasserstoffs durch Halogen (I. Mitteil.)

Cited by 125 publications

References 16 publications

The X-ray Structure of trans-3-Chloroacrylic Acid Dehalogenase Reveals a Novel Hydration Mechanism in the Tautomerase Superfamily

The X-ray Structure of trans-3-Chloroacrylic Acid Dehalogenase Reveals a Novel Hydration Mechanism in the Tautomerase Superfamily

Ultrafast photoinduced dynamics of halogenated cyclopentadienes: observation of geminate charge-transfer complexes in solution

Steric and Electronic Effects on an Antibody‐Catalyzed Diels–Alder Reaction

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