- Expanding the scope of N → S acyl transfer in native peptide sequences
-
Understanding the factors that influence N → S acyl transfer in native peptide sequences, and discovery of new reagents that facilitate it, will be key to expanding its scope and applicability. Here, through a study of short model peptides in thioester formation and cyclisation reactions, we demonstrate that a wider variety of Xaa-Cys motifs than originally envisaged are capable of undergoing efficient N → S acyl transfer. We present data for the relative rates of thioester formation and cyclisation for a representative set of amino acids, and show how this expanded scope can be applied to the production of the natural protease inhibitor Sunflower Trypsin Inhibitor-1 (SFTI-1).
- Cowper, Ben,Shariff, Leila,Chen, Wenjie,Gibson, Samantha M.,Di, Wei-Li,Macmillan, Derek
-
-
Read Online
- Synthesis and cellular penetration properties of new phosphonium based cationic amphiphilic peptides
-
A new category of phosphonium based cationic amphiphilic peptides has been developed and evaluated as potential antimicrobial peptides and cell penetrating peptides. The required building blocks were conveniently accessible from cysteine and could be applied in a solid phase peptide synthesis protocol for incorporation into peptide sequences. Evaluation of the antimicrobial properties and cellular toxicity of these phosphonium based peptides showed that these "soft" cationic side-chain containing peptides have poor antimicrobial properties and most of them were virtually non toxic (on HEK cells tested at 256 and 512 μM) and non-haemolytic (on horse erythrocytes tested at 512 μM), hinting at an interesting potential application as cell penetrating peptides. This possibility was evaluated using fluorescent peptide derivatives and showed that these phosphonium based peptide derivatives were capable of entering HEK cells and depending on the sequence confined to specific cellular areas.
- Silva Nigenda, Ezequiel,Postma, Tobias M.,Hezwani, Mohammed,Pirvan, Alin,Gannon, Susan,Smith, Carol-Anne,Riehle, Mathis,Liskamp, Rob M. J.
-
-
Read Online
- Protein ubiquitination: Via dehydroalanine: Development and insights into the diastereoselective 1,4-addition step
-
We report a strategy for site-specific protein ubiquitination using dehydroalanine (Dha) chemistry for the preparation of ubiquitin conjugates bearing a very close mimic of the native isopeptide bond. Our approach relies on the selective formation of Dha followed by conjugation with hexapeptide bearing a thiol handle derived from the C-terminal of ubiquitin. Subsequently, the resulting synthetic intermediate undergoes native chemical ligation with the complementary part of the ubiquitin polypeptide. It has been proposed that the Michael addition step could result in the formation of a diastereomeric mixture as a result of unselective protonation of the enolate intermediate. It has also been proposed that the chiral protein environment may influence such an addition step. In the protein context these questions remain open and no experimental evidence was provided as to how such a protein environment affects the diastereoselectivity of the addition step. As was previously proposed for the conjugation step on protein bearing Dha, the isopeptide bond formation step in our study resulted in the construction of two protein diastereomers. To assign the ratio of these diastereomers, trypsinization coupled with high-pressure liquid chromatography analysis were performed. Moreover, the obtained peptide diastereomers were compared with identical synthetic peptides having defined stereogenic centers, which enabled the determination of the configuration of the isopeptide mimic in each diastereomer. Our study, which offers a new method for isopeptide bond formation and protein ubiquitination, gives insights into the parameters that affect the stereoselectivity of the addition step to Dha for chemical protein modifications.
- Meledin, Roman,Mali, Sachitanand M.,Singh, Sumeet K.,Brik, Ashraf
-
-
Read Online
- LIQUID COMPOSITIONS COMPRISING A LEVODOPA AMINO ACID CONJUGATE AND USES THEREOF
-
Disclosed herein are liquid pharmaceutical formulations comprising levodopa amino acid conjugates that may further comprise a decarboxylase inhibitor, such as carbidopa, an antioxidant, a solvent, or any other pharmaceutically acceptable excipient. Further disclosed are methods of treating generative conditions and/or conditions characterized by reduced levels of dopamine in the brain, such as Parkinson's disease, comprising administering the disclosed liquid pharmaceutical formulations. Disclosed also are LDAA conjugate compounds.
- -
-
Page/Page column 74
(2021/03/13)
-
- Visible-Light-Mediated S?H Bond Insertion Reactions of Diazoalkanes with Cysteine Residues in Batch and Flow
-
We describe the application of S?H bond insertion reactions of aryl diazoacetates with cysteine residues that enabled metal-free, S?H functionalization under visible-light conditions. Moreover, this process could be intensified by a continuous-flow photomicroreactor on the acceleration of the reaction (6.5 min residence time). The batch and flow protocols described were applied to obtain a wide range of functionalized cysteine derivatives and cysteine-containing dipeptides, thus providing a straightforward and general platform for their functionalizations in mild conditions. (Figure presented.).
- Chen, Lin,Cui, Yu-Sheng,Duan, Xiu,Guo, Kai,Qin, Long-Zhou,Qiu, Jiang-Kai,Sun, Qi,Yuan, Xin,Zhuang, Kai-Qiang
-
p. 5093 - 5104
(2020/09/23)
-
- Mild, Rapid, and Chemoselective Procedure for the Introduction of the 9-Phenyl-9-fluorenyl Protecting Group into Amines, Acids, Alcohols, Sulfonamides, Amides, and Thiols
-
The 9-phenyl-9-fluorenyl (PhF) group has been used as an Nα protecting group of amino acids and their derivatives mainly as a result of its ability to prevent racemization. However, installing this group using the standard protocol, which employs 9-bromo-9-phenylfluorene/K3PO4/Pb(NO3)2, often takes days and yields can be variable. Here, we demonstrate that the PhF group can be introduced into the amino group of Weinreb's amides and methyl esters of amino acids, as well as into alcohols and carboxylic acids, rapidly and in excellent yields, using 9-chloro-9-phenylfluorene (PhFCl)/N-methylmorpholine (NMM)/AgNO3. Nα-PhF-protected amino acids can be prepared from unprotected α-amino acids, rapidly and often in near quantitative yields, by treatment with N,O-bis(trimethylsilyl)acetamide (BSA) and then PhFCl/NMM/AgNO3. Primary alcohols can be protected with the PhF group in the presence of secondary alcohols in moderate yield. Using PhFCl/AgNO3, a primary alcohol can be protected in good yield in the presence of a primary ammonium salt or a carboxylic acid. Primary sulfonamides and amides can be protected in moderate to good yields using phenylfluorenyl alcohol (PhFOH)/BF3·OEt2/K3PO4, while thiols can be protected in good to excellent yield using PhFOH/BF3·OEt2 even in the presence of a carboxylic acid or primary ammonium group.
- Soley, Jacob,Taylor, Scott D.
-
-
- Synthesis and NMR Characterization of the Prenylated Peptide, a-Factor
-
Protein and peptide prenylation is an essential biological process involved in many signal transduction pathways. Hence, it plays a critical role in establishing many major human ailments, including Alzheimer's disease, amyotrophic lateral sclerosis (ALS), malaria, and Ras-related cancers. Yeast mating pheromone a-factor is a small dodecameric peptide that undergoes prenylation and subsequent processing in a manner identical to larger proteins. Due to its small size in addition to its well-characterized behavior in yeast, a-factor is an attractive model system to study the prenylation pathway. Traditionally, chemical synthesis and characterization of a-factor have been challenging, which has limited its use in prenylation studies. In this chapter, a robust method for the synthesis of a-factor is presented along with a description of the characterization of the peptide using MALDI and NMR. Finally, complete assignments of resonances from the isoprenoid moiety and a-factor from COSY, TOCSY, HSQC, and long-range HMBC NMR spectra are presented. This methodology should be useful for the synthesis and characterization of other mature prenylated peptides and proteins.
- Bader, Taysir K.,Rappe, Todd M.,Veglia, Gianlugi,Distefano, Mark D.
-
p. 207 - 238
(2019/01/04)
-
- NOVEL COMPOUNDS
-
A compound of formula (I) or a pharmaceutically acceptable derivative thereof, (formula 1) wherein R1,R2, R3, R4, R5, X, m and n are defined in the specification; a process for preparing such compounds; a pharmaceutical composition comprising such compounds; and the use of such compounds in medicine.
- -
-
Page/Page column 51
(2016/02/26)
-
- Expanding the scope of N → S acyl transfer in native peptide sequences
-
Understanding the factors that influence N → S acyl transfer in native peptide sequences, and discovery of new reagents that facilitate it, will be key to expanding its scope and applicability. Here, through a study of short model peptides in thioester formation and cyclisation reactions, we demonstrate that a wider variety of Xaa-Cys motifs than originally envisaged are capable of undergoing efficient N → S acyl transfer. We present data for the relative rates of thioester formation and cyclisation for a representative set of amino acids, and show how this expanded scope can be applied to the production of the natural protease inhibitor Sunflower Trypsin Inhibitor-1 (SFTI-1).
- Cowper, Ben,Shariff, Leila,Chen, Wenjie,Gibson, Samantha M.,Di, Wei-Li,MacMillan, Derek
-
p. 7469 - 7476
(2015/11/27)
-
- Synthesis of Peptides Containing C-Terminal Esters Using Trityl Side-Chain Anchoring: Applications to the Synthesis of C-Terminal Ester Analogs of the Saccharomyces cerevisiae Mating Pheromone a -Factor
-
Peptides containing C-terminal esters are an important class of bioactive molecules that includes a-factor, a farnesylated dodecapeptide, involved in the mating of Saccharomyces cerevisiae. Here, results that expand the scope of solid-phase peptide synthetic methodology that uses trityl side-chain anchoring for the preparation of peptides with C-terminal cysteine alkyl esters are described. In this method, Fmoc-protected C-terminal cysteine esters are anchored to trityl chloride resin and extended by standard solid-phase procedures followed by acidolytic cleavage and HPLC purification. Analysis using a Gly-Phe-Cys-OMe model tripeptide revealed minimal epimerization of the C-terminal cysteine residue under basic conditions used for Fmoc deprotection. 1H NMR analysis of the unfarnesylated a-factor precursor peptide confirmed the absence of epimerization. The side-chain anchoring method was used to produce wild-type a-factor that contains a C-terminal methyl ester along with ethyl-, isopropyl-, and benzyl-ester analogs in good yield. Activity assays using a yeast-mating assay demonstrate that while the ethyl and isopropyl esters manifest near-wild-type activity, the benzyl ester-containing analog is ca. 100-fold less active. This simple method opens the door to the synthesis of a variety of C-terminal ester-modified peptides that should be useful in studies of protein prenylation and other structurally related biological processes.
- Diaz-Rodriguez, Veronica,Ganusova, Elena,Rappe, Todd M.,Becker, Jeffrey M.,Distefano, Mark D.
-
p. 11266 - 11274
(2015/12/04)
-
- Synthesis of peptides containing C -terminal methyl esters using trityl side-chain anchoring: Application to the synthesis of a-factor and a-factor analogs
-
A new cysteine anchoring method was developed for the synthesis of peptides containing C-terminal cysteine methyl esters. This method consists of attachment of Fmoc-Cys-OCH3 to either 2-ClTrt-Cl or Trt-Cl resins (via the side-chain thiol) followed by preparation of the desired peptide using Fmoc-based SPPS. We applied this method to the synthesis of the mating pheromone a-factor and a 5-FAM labeled a-factor analog. The peptides were obtained with high yield and purity and were shown to be bioactive in a growth arrest assay.
- Diaz-Rodriguez, Veronica,Mullen, Daniel G.,Ganusova, Elena,Becker, Jeffrey M.,Distefano, Mark D.
-
supporting information
p. 5648 - 5651
(2013/01/15)
-
- One-pot synthesis of unsymmetrical disulfides using 1-chlorobenzotriazole as oxidant: Interception of the sulfenyl chloride intermediate
-
A high-yielding and low temperature one-pot procedure is described for unsymmetrical disulfide synthesis from two different thiols using 1-chlorobenzotriazole (BtCl) as oxidant. The mechanism of the coupling involves in situ trapping of the sulfenyl chloride intermediate R1SCl by nucleophilic benzotriazole (BtH) to form R1SBt, which protects R1SCl from forming the homodimer R1SSR1. The methodology is applicable to all types of thiol (aliphatic, aromatic, heteroaromatic), with a variation developed for aliphatic-aliphatic couplings. Differentially N-protected cysteines couple to afford the unsymmetrical cystine derivatives in high yield (90%), which serves as a model for the one-pot intermolecular coupling of cysteine-containing peptides to form peptide disulfide heterodimers. Minimal exchange in aromatic-aromatic disulfide synthesis is noted on account of the mild conditions.
- Stellenboom, Nashia,Hunter, Roger,Caira, Mino R.
-
experimental part
p. 3228 - 3241
(2010/06/13)
-
- The stereospecific synthesis of 'orthogonally' protected lanthionines
-
Lanthionine is an attractive monomer for the design and synthesis of novel conformationally constrained peptidomimetics, since unlike cystine, the monosulfur bridge of lanthionine is chemically far more robust and also displays a greater degree of conformational rigidity. The synthesis of lanthionine residues for use in peptide synthesis is non-trivial due to the protectional requirements necessary for this tetra-functional amino acid. In this paper an efficient stereo-specific route to orthogonally protected lanthionine is described.
- Swali, Vinay,Matteucci, Mizio,Elliot, Richard,Bradley, Mark
-
p. 9101 - 9109
(2007/10/03)
-
- Allylic protection of thiols and cysteine: II: The N-[2,3,5,6- tetrafluoro-4-(N'-piperidino)-phenyl], N-allyloxycarbonylaminomethyl (Fnam) group
-
S-[N-[2,3,5,6-tetrafluoro-4-(N'-piperidino)-phenyl], N- allyloxycarbonyl]-aminomethyl (Fnam) derivatives of thiols in general and cysteine in particular are readily deprotected by palladium catalysed allylic cleavage in the presence of various nucleophilic species. They are perfectly stable in both the basic conditions (piperidine/DMF) of Fmoc group removal and the acidic conditions (TFA/CH2Cl2) of t-Bu and Boc group removal.
- Gomez-Martinez, Paloma,Kimbonguila, Andre Malanda,Guibe, Francois
-
p. 6945 - 6960
(2007/10/03)
-
- Allylic protection of thiols and cysteine: I: The allyloxycarbonylaminomethyl group
-
S-allyloxycarbonylaminomethyl derivatives of thiols in general and cysteine in particular are readily deprotected by palladium catalysed hydrostannolysis with tributyltin hydride in the presence of acetic acid. They are perfectly stable in the basic conditions (piperidine/DMF) of Fmoc group removal but tend to decompose, albeit slowly, in the acidic conditions (TFA/CH2Cl2) of t-Bu and Boc groups removal.
- Kimbonguila, Andre Malanda,Merzouk, Ahmed,Guibe, Francois,Loffet, Albert
-
p. 6931 - 6944
(2007/10/03)
-