Simple route to sterically pure diketopiperazines

Nitecki, Danute E.; Halpern, B.; Westley, John

doi:10.1021/jo01266a091

Cited by 184 publications

(87 citation statements)

References 6 publications

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“…Products were identified by NMR techniques and combustion analysis. Synthesis of a,a'-substituted cyclic dipeptides (diketopiperazines) followed the method devised by Nitecki et al [13] Starting from Nboc-(boc = tert-butoxycarbonyl) and C-ester-protected dipeptides, the cyclic peptides were obtained after acidic deprotection of the boc group in formic acid followed by thermally induced ring closure. ).…”

Section: Methodsmentioning

confidence: 99%

Conformational Influence on the Type of Stabilization of Sulfur Radical Cations in Cyclic Peptides

Hug¹,

Bobrowski²,

Pogocki³

et al. 2007

ChemPhysChem

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The free-radical chemistry of two oxidized cyclic dipeptides is investigated using time-resolved optical and conductivity detection. Two cyclic dipeptides, cyclo-Gly-L-Met and cyclo-D-Met-L-Met, are synthesized and irradiated with nanosecond pulses of electrons, which initiate the oxidation of the methionine side chains with hydroxyl radicals from the radiolysis of water. The cyclic peptides are taken to be models for the interior of proteins where there are no terminal groups. This opens up the possibility that neighboring-group effects can be studied directly between the initially formed sulfur radical cations and the heteroatoms associated with the peptide bonds. Such complexation of the sulfur radical cations is observed with the amide nitrogen atoms. In addition, intermolecular stabilization with the unoxidized sulfur atoms on separate cyclic dipeptide molecules is observed. Little or no intramolecular stabilization by the unoxidized sulfur in the neighboring methionine occurs in cyclo-D-Met-L-Met, in contrast to the previously observed intramolecular sulfur stabilization of the sulfur radical cation in the isomer cyclo-L-Met-L-Met. This contrasting behavior is rationalized by conformational differences in the two isomers as seen through molecular-modeling simulations. The implications for the oxidation of the protein calmodulin, which contains multiple residues of methionine, are discussed as having analogous determining factors.

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Section: Methodsmentioning

confidence: 99%

Conformational Influence on the Type of Stabilization of Sulfur Radical Cations in Cyclic Peptides

Hug¹,

Bobrowski²,

Pogocki³

et al. 2007

ChemPhysChem

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“…The synthesis and characterization of the following cyclo(dipeptide)s have been reported in the literature: cyclo(glycyl-L-alanyl) (1) (33,34), cyclo(glycyl-L-valyl) (2) (33,35), cyclo(glycyl-L-leucyl) (3) (33,36), cyclo(glycyl-Lphenylalanyl) (4) (33,(36)(37)(38)(39), cyclo(glycyl-L-phenylglycyl) (5) (33,38), cyclo(L-valyl-L-valyl) (6) (33,35), cyclo(Lvalyl-L-leucyl) (7) (37), cyclo(L-leucyl-L-leucyl) (8) (33,36,37), cyclo(L-phenylalanyl-L-leucyl) (9) (36,37), and cyclo(L-phenylalanyl-L-phenylalanyl) (10) (33,37). On the other hand, the cyclo(dipeptide)s below were firstly synthesized in this study: cyclo(glycyl-L-γ -ethylglutamyl) (11), cyclo(L-valyl-L-γ -ethylglutamyl) (12), cyclo(L-valyl-L-γ -dodecylglutamyl) (13), cyclo(L-valyl-L-γ -octadecylglutamyl) (14), cyclo(L-valyl-L-γ -3,7-dimethyloctylglutamyl) (15), cyclo(L-valyl-L-γ -2-ethylhexylglutamyl) (16), cyclo(L-leucyl-L-glutamyl) (17), cyclo(L-leucyl-L-γ -ethylglutamyl) (18), cyclo(L-leucyl-L-γ -dodecylglutamyl) (19), cyclo(L-leucyl-L-γ -3,7-dimethyloctylglutamyl) (20), cyclo(L-leucyl-L-γ -benzylglutamyl) (21), cyclo(L-asparaginyl-L-phenylalanyl) (22), cyclo(L-β-butylasparaginyl-L-phenylalanyl) (23), cyclo(L-γ -dodecylasparaginyl-L-phenylalanyl) (24), cyclo(L-β-3, SCHEME 1…”

Section: Gelation Abilitiesmentioning

confidence: 99%

Low Molecular Weight Gelators for Organic Fluids: Gelation Using a Family of Cyclo(dipeptide)s

Hanabusa

Matsumoto

Kimura

et al. 2000

Journal of Colloid and Interface Science

162

127

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“…A P450 monooxygenase, TxtC, then hydroxylates the l ‐phenylalanine residue at the α‐position and at either 2‐, 3‐, or 4‐positions of the aryl group resulting in a family of compounds ( 4 – 11 ) with thaxtomin A ( 6 ) being the major metabolite produced by S. scabies 25, 26, 27, 28. The potent herbicidal activity and novel mode of action has driven the development of several synthetic routes to thaxtomins 29, 30, 31, 32, 33, 34, 35, 36. However, these routes are all multi‐step, low yielding, and produce diastereoisomeric mixtures.…”

mentioning

confidence: 99%

De novo Biosynthesis of “Non‐Natural” Thaxtomin Phytotoxins

2018

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Thaxtomins are diketopiperazine phytotoxins produced by Streptomyces scabies and other actinobacterial plant pathogens that inhibit cellulose biosynthesis in plants. Due to their potent bioactivity and novel mode of action there has been considerable interest in developing thaxtomins as herbicides for crop protection. To address the need for more stable derivatives, we have developed a new approach for structural diversification of thaxtomins. Genes encoding the thaxtomin NRPS from S. scabies, along with genes encoding a promiscuous tryptophan synthase (TrpS) from Salmonella typhimurium, were assembled in a heterologous host Streptomyces albus. Upon feeding indole derivatives to the engineered S. albus strain, tryptophan intermediates with alternative substituents are biosynthesized and incorporated by the NRPS to deliver a series of thaxtomins with different functionalities in place of the nitro group. The approach described herein, demonstrates how genes from different pathways and different bacterial origins can be combined in a heterologous host to create a de novo biosynthetic pathway to “non‐natural” product target compounds.

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Simple route to sterically pure diketopiperazines

Cited by 184 publications

References 6 publications

Conformational Influence on the Type of Stabilization of Sulfur Radical Cations in Cyclic Peptides

Conformational Influence on the Type of Stabilization of Sulfur Radical Cations in Cyclic Peptides

Low Molecular Weight Gelators for Organic Fluids: Gelation Using a Family of Cyclo(dipeptide)s

De novo Biosynthesis of “Non‐Natural” Thaxtomin Phytotoxins

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