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K. T. Douglas - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of symmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 1
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of a series of symmetrical disulfides as potential substrates of trypanothione reductase and glutathione reductase was described. The key intermediate in the synthetic approach was the choice of S-^tbutylmercapto-L-cysteine (1). The spermidine ring in the native substrate, trypanothione disulfide (TSST), was replaced with 3-dimethyl-aminopropylamine (DMAPA), while the γ -Glu moiety was replaced by phenylalanyl or tryptophanyl residues. The same modifications in the γ -Glu moiety of glutathione disulfide (GSSG) were applied.
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Synthesis of asymmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 2
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of asymmetrical disulfides, based on Zervas' inter-mediate, monocarbobenzoxy-L-cystine, has been developed. A series of substrate analogues of trypanothione disulfide (TSST) and glutathione disulfide (GSSG) are described, where the spermidine ring of (TSST) has been replaced by 3-dimethylaminopropylamine (DMAPA). The free amino group in Zervas' product was condensed with phenylalanyl, tryptophanyl or glutamyl residues, while the carbobenzoxy group was unaffected under the reaction conditions employed. The same synthetic approach was applied in the design of analogues of glutathione disulfide (GSSG).
Rabih Jaouhari - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of symmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 1
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of a series of symmetrical disulfides as potential substrates of trypanothione reductase and glutathione reductase was described. The key intermediate in the synthetic approach was the choice of S-^tbutylmercapto-L-cysteine (1). The spermidine ring in the native substrate, trypanothione disulfide (TSST), was replaced with 3-dimethyl-aminopropylamine (DMAPA), while the γ -Glu moiety was replaced by phenylalanyl or tryptophanyl residues. The same modifications in the γ -Glu moiety of glutathione disulfide (GSSG) were applied.
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Synthesis of asymmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 2
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of asymmetrical disulfides, based on Zervas' inter-mediate, monocarbobenzoxy-L-cystine, has been developed. A series of substrate analogues of trypanothione disulfide (TSST) and glutathione disulfide (GSSG) are described, where the spermidine ring of (TSST) has been replaced by 3-dimethylaminopropylamine (DMAPA). The free amino group in Zervas' product was condensed with phenylalanyl, tryptophanyl or glutamyl residues, while the carbobenzoxy group was unaffected under the reaction conditions employed. The same synthetic approach was applied in the design of analogues of glutathione disulfide (GSSG).
David J. Craik - One of the best experts on this subject based on the ideXlab platform.
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Fmoc-Based Synthesis of Disulfide-Rich Cyclic Peptides
Journal of Organic Chemistry, 2014Co-Authors: Olivier Cheneval, Christina I. Schroeder, Thomas Durek, Phillip Walsh, Yen-hua Huang, Spiros Liras, David A. Price, David J. CraikAbstract:Disulfide-rich cyclic peptides have exciting potential as leads or frameworks in drug discovery; however, their use is faced with some synthetic challenges, mainly associated with construction of the circular backbone and formation of the correct disulfides. Here we describe a simple and efficient Fmoc solid-phase peptide synthesis (SPPS)-based method for synthesizing disulfide-rich cyclic peptides. This approach involves SPPS on 2-chlorotrityl resin, cyclization of the partially protected peptide in solution, cleavage of the side-chain protecting groups, and oxidization of cysteines to yield the desired product. We illustrate this method with the synthesis of peptides from three different classes of cyclic cystine knot motif-containing cyclotides: Mobius (M), trypsin inhibitor (T), and bracelet (B). We show that the method is broadly applicable to peptide engineering, illustrated by the synthesis of two mutants and three grafted analogues of kalata B1. The method reduces the use of highly caustic and tox...
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Knots in rings. The circular knotted protein Momordica cochinchinensis trypsin inhibitor-II folds via a stable two-disulfide intermediate.
Journal of Biological Chemistry, 2006Co-Authors: Maša Čemažar, Sara Häggblad, Kai Pong Lo, Ernie Yulyaningsih, Norelle L Daly, David J. CraikAbstract:The aim of this work was to elucidate the oxidative folding mechanism of the macrocyclic cystine knot protein MCoTI-II. We aimed to investigate how the six-cysteine residues distributed on the circular backbone of the reduced unfolded peptide recognize their correct partner and join up to form a complex cystine-knotted topology. To answer this question, we studied the oxidative folding of the naturally occurring peptide using a range of spectroscopic methods. For both oxidative folding and reductive unfolding, the same disulfide intermediate species was prevalent and was characterized to be a native-like two-disulfide intermediate in which the Cys(1)-Cys(18) disulfide bond was absent. Overall, the folding pathway of this head-to-tail cyclized protein was found to be similar to that of linear cystine knot proteins from the squash family of trypsin inhibitors. However, the pathway differs in an important way from that of the cyclotide kalata B1, in that the equivalent two-disulfide intermediate in that case is not a direct precursor of the native protein. The size of the embedded ring within the cystine knot motif appears to play a crucial role in the folding pathway. Larger rings contribute to the independence of disulfides and favor an on-pathway native-like intermediate that has a smaller energy barrier to cross to form the native fold. The fact that macrocyclic proteins are readily able to fold to a complex knotted structure in vitro in the absence of chaperones makes them suitable as protein engineering scaffolds that have remarkable stability.
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disulfide mapping of the cyclotide kalata b1 chemical proof of the cyclic cystine knot motif
Journal of Biological Chemistry, 2003Co-Authors: Ulf Goransson, David J. CraikAbstract:The cyclotides are a recently discovered family of plant proteins that have the fascinating structural feature of a continuous cyclic backbone and, putatively, a knotted arrangement of their three conserved disulfide bonds. We here show definite chemical proof of the I-IV, II-V, III-VI knotted disulfide connectivity of the prototypic cyclotide kalata B1. This has been achieved by a new approach for disulfide analysis, involving partial reduction and stepwise alkylation including introduction of charges and enzymatic cleavage sites by aminoethylation of cysteines. The approach overcomes the intrinsic difficulties for disulfide mapping of cyclotides, i.e. the cyclic amide backbone, lack of cleavage sites between cysteines, and a low or clustered content of basic amino acids, and allowed a direct determination of the disulfide bonds in kalata B1 using analysis by mass spectrometry. The established disulfide connectivity is unequivocally shown to be cystine knotted by a topological analysis. This is the first direct chemical determination of disulfides in native cyclotides and unambiguously confirms the unique cyclic cystine knot motif.
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solution structures of the cis and trans pro30 isomers of a novel 38 residue toxin from the venom of hadronyche infensa sp that contains a cystine knot motif within its four disulfide bonds
Biochemistry, 2002Co-Authors: Johan K Rosengren, Paul F. Alewood, Norelle L Daly, David Wilson, David J. CraikAbstract:The primary sequence and three-dimensional structure of a novel peptide toxin isolated from the Australian funnel-web spider Hadronyche infensa sp. is reported. ACTX-Hi:OB4219 contains 38 amino acids, including eight-cysteine residues that form four disulfide bonds. The connectivities of these disulfide bonds were previously unknown but have been unambiguously determined in this study. Three of these disulfide bonds are arranged in an inhibitor cystine-knot (ICK) motif, which is observed in a range of other disulfide-rich peptide toxins. The motif incorporates an embedded ring in the structure formed by two of the disulfides and their connecting backbone segments penetrated by a third disulfide bond. Using NMR spectroscopy, we determined that despite the isolation of a single native homologous product by RP-HPLC, ACTX-Hi:OB4219 possesses two equally populated conformers in solution. These two conformers were determined to arise from cis/trans isomerization of the bond preceding Pro30. Full assignment of t...
T. Besheya - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of symmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 1
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of a series of symmetrical disulfides as potential substrates of trypanothione reductase and glutathione reductase was described. The key intermediate in the synthetic approach was the choice of S-^tbutylmercapto-L-cysteine (1). The spermidine ring in the native substrate, trypanothione disulfide (TSST), was replaced with 3-dimethyl-aminopropylamine (DMAPA), while the γ -Glu moiety was replaced by phenylalanyl or tryptophanyl residues. The same modifications in the γ -Glu moiety of glutathione disulfide (GSSG) were applied.
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Synthesis of asymmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 2
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of asymmetrical disulfides, based on Zervas' inter-mediate, monocarbobenzoxy-L-cystine, has been developed. A series of substrate analogues of trypanothione disulfide (TSST) and glutathione disulfide (GSSG) are described, where the spermidine ring of (TSST) has been replaced by 3-dimethylaminopropylamine (DMAPA). The free amino group in Zervas' product was condensed with phenylalanyl, tryptophanyl or glutamyl residues, while the carbobenzoxy group was unaffected under the reaction conditions employed. The same synthetic approach was applied in the design of analogues of glutathione disulfide (GSSG).
James H Mckie - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of symmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 1
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of a series of symmetrical disulfides as potential substrates of trypanothione reductase and glutathione reductase was described. The key intermediate in the synthetic approach was the choice of S-^tbutylmercapto-L-cysteine (1). The spermidine ring in the native substrate, trypanothione disulfide (TSST), was replaced with 3-dimethyl-aminopropylamine (DMAPA), while the γ -Glu moiety was replaced by phenylalanyl or tryptophanyl residues. The same modifications in the γ -Glu moiety of glutathione disulfide (GSSG) were applied.
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Synthesis of asymmetric disulfides as potential alternative substrates for trypanothione reductase and glutathione reductase: Part 2
Amino Acids, 1995Co-Authors: Rabih Jaouhari, James H Mckie, T. Besheya, K. T. DouglasAbstract:The synthesis of asymmetrical disulfides, based on Zervas' inter-mediate, monocarbobenzoxy-L-cystine, has been developed. A series of substrate analogues of trypanothione disulfide (TSST) and glutathione disulfide (GSSG) are described, where the spermidine ring of (TSST) has been replaced by 3-dimethylaminopropylamine (DMAPA). The free amino group in Zervas' product was condensed with phenylalanyl, tryptophanyl or glutamyl residues, while the carbobenzoxy group was unaffected under the reaction conditions employed. The same synthetic approach was applied in the design of analogues of glutathione disulfide (GSSG).