Cooperative Stapling of Native Peptides at Lysine and Tyrosine or Arginine with Formaldehyde

2020 ◽  
Author(s):  
Bo Li ◽  
Hong Tang ◽  
Aneta Turlik ◽  
Zhao Wan ◽  
Xiao-Song Xue ◽  
...  
Keyword(s):  
Native Peptides

scholarly journals Celiac Disease

2001 ◽  
Vol 47 (11) ◽  
pp. 2023-2028 ◽  
Author(s):  
Mabel Aleanzi ◽  
Ana María Demonte ◽  
Cecilia Esper ◽  
Silvia Garcilazo ◽  
Marta Waggener
Keyword(s):  
Celiac Disease ◽  
Tissue Transglutaminase ◽  
Gluten Free ◽  
Antibody Recognition ◽  
Modified Peptides ◽  
Gliadin Peptides ◽  
Circulating Antibodies ◽  
Native Peptides ◽  
Gliadin Antibody ◽  
Circulating Antibody

Abstract Background: Selective deamidation of glutamine residues by tissue transglutaminase (tTG) turns gliadin peptides into stronger activators of T cells from celiac disease (CD) patients. We examined the possibility that these modified peptides could be more specific epitopes for circulating antibodies than are native peptides. Methods: Two native synthetic peptides and their respective modified sequences were used as antigens for ELISA assays: peptide-1, with residues 56–75 of α-type gliadin; and peptide-2, with residues 134–153 of γ-type gliadin. We examined 40 CD patients [31 not being treated with a gluten-free diet (GFD) and 9 being treated with a GFD] and 30 non-CD patients. Results: An enhanced response against deamidated peptides was observed in 4 (IgA) and 22 (IgG) of 31 untreated CD patients for peptide-1 and in 25 (IgA) and 29 (IgG) patients for peptide-2. Higher anti-gliadin antibody and anti-tTG IgA concentrations correlated with increased IgA reactivity to modified peptides. Among the nine treated CD patients, eight also displayed an improved IgG signal for the deamidated sequence. Deamidation of peptides did not increase the reactivity of non-CD sera. Conclusions: Selective deamidation specifically increases circulating antibody recognition of gliadin peptides in CD patients. This suggests that deamidated gliadin peptides are more specific CD B-cell epitopes than native peptides; this finding may be relevant for designing improved diagnostic tests.

Determination with Matrix-Assisted Laser Desorption/Ionization Tandem Time-of-Flight Mass Spectrometry of the Extensive Disulfide Bonding in Tarantula Venom Peptide Psalmopeotoxin I

2009 ◽  
Vol 15 (4) ◽  
pp. 517-529 ◽  
Author(s):  
Audrey Combes ◽  
Soo Jin Choi ◽  
Cyril Pimentel ◽  
Hervé Darbon ◽  
Dietmar Waidelich ◽  
...  
Keyword(s):  
Laser Desorption ◽  
Disulfide Bridge ◽  
Fragmentation Pattern ◽  
Laser Desorption Ionization ◽  
Disulfide Bridges ◽  
Wild Type ◽  
Desorption Ionization ◽  
Native Peptides ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Psalmopeotoxin I (PcFK1) is a 33-residue peptide isolated from the venom of the tarantula Psalmopoeus cambridgei. This peptide specifically inhibits the intra-erythrocyte stage of Plasmodium falciparum in vitro. It contains six cysteine residues forming three disulfide bridges and belongs to the superfamily of natural peptides containing the inhibitor cystine knot (ICK) fold. We produced the wild-type and mutated forms of the recombinant peptide to examine the mechanism of action of PcFK1. The purified toxins were consistently produced as two isobaric peptides (r-PcFK1-1 and r-PcFK1-2) with different retention properties but identical anti-plasmodial biological activity. Comparison of 15N-NMR heteronuclear single quantum correlation spectra revealed that although rPcFK1-1 was highly structured, rPcFK1-2 does not have a stable three-dimensional structure. We used high-energy collision-induced fragmentation of the peptides with a matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometer to further investigate the structure of the native peptides in its natural form and produced in E. coli. The fragmentation spectra of the native peptides were very complex due to the occurrence in the spectrum of ions resulting from (1) cross-linking of fragments through a disulfide bridge and (2) asymmetric fragmentations of the disulfide bridges and (3) multiple neutral losses. The tandem mass spectrometry fragmentation pattern of r-PcFK1-1 was similar to that of the natural peptide isolated from crude venom, but r-PcFK1-2 had a clearly distinct fragmentation pattern, more closely resembling the fragmentation spectra of reduced and alkylated peptides. Observed ions could be attributed to specific fragments by comparing spectra between the wild-type and selected variants with point mutations (Y11W, R20T, Y26W, K28V). The disulfide connections in r-PcFK1-2 differed from those of the native peptide and showed a rare disulfide bridge between vicinal cysteine residues. The r-PcFK1_(R20T) variant showed a very limited fragmentation pattern when analyzed in positive mode but displayed much more fragmentation in negative mode pointing out the importance of the R20 residue in the fragmentation of PcFK1. Using the reductive matrix 1,5-diaminonaphtalene promoted strongly in source decay fragmentation of the peptides in MS mode. Our findings illustrated the critical role of the electronic environment around the central Cys18–Cys19 doublet in PcFK1 in internal fragmentation of the peptide.

scholarly journals Detection of native peptides as potent inhibitors of enzymes

FEBS Journal ◽  
2004 ◽  
Vol 272 (2) ◽  
pp. 562-572 ◽  
Author(s):  
Nagendra Singh ◽  
Talat Jabeen ◽  
Sujata Sharma ◽  
Ipsita Roy ◽  
Munishwar N. Gupta ◽  
...  
Keyword(s):  
Native Peptides

scholarly journals Interfacing native and non-native peptides: using Affimers to recognise α-helix mimicking foldamers

2017 ◽  
Vol 53 (19) ◽  
pp. 2834-2837 ◽  
Author(s):  
Irene Arrata ◽  
Anna Barnard ◽  
Darren C. Tomlinson ◽  
Andrew J. Wilson
Keyword(s):  
Selection Methods ◽  
Native Peptides ◽  
Α Helix

Selection methods are used to identify Affimers that recognise α-helix mimicking N-alkylated aromatic oligoamides.

Successful Generation of Cytotoxic T-Cells That Kill CLL Cells Using Heteroclitic Peptides Is Independent of the Native Peptide Binding Affinity to HLA-A*0201.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 54-54 ◽  
Author(s):  
Katja Mauerer ◽  
Gullu Gorgun ◽  
David Zahrieh ◽  
John G. Gribben
Keyword(s):  
Tumor Cells ◽  
Binding Affinity ◽  
Mhc Class I ◽  
Binding Assay ◽  
Cytotoxic T Cells ◽  
B Cell Malignancies ◽  
Specific Lysis ◽  
Native Peptide ◽  
Native Peptides ◽  
Heteroclitic Peptides

Abstract Targeting immunoglobulin (Ig) framework region (FR) derived peptides offers the advantage of a less patient specific immunotherapeutic strategy in B-cell malignancies. A major limitation of this method is the generally low immunogenicity and low binding affinity of these peptides to MHC class I and class II molecules. Heteroclitic peptide modifications can increase immunogenicity of low binding peptides while leaving T-cell recognition residues intact, and improve ability to generate cytotoxic T cells lines (CTL). It is not known whether such CTLs can still kill tumor cells that express native peptides below a lower threshold of binding affinity. To address this, we sequenced Ig, identified nonameric and decameric peptide sequences that potentially bind to HLA-A*0201 (HLA-A2) that were frequently shared among patients. We used two independent computer prediction analysis tools, determined binding using the T2-binding assay, screened peptide specific CTL responses with an established T-cell expansion system, and assessed cytotoxicity of the CTL lines against native and heteroclitic peptide pulsed APCs and also primary tumor cells from which the native peptides were derived. 34 FR-derived peptides were synthesized, 17 native peptides selected to represent a wide range of predicted binding to HLA-A2, and 17 corresponding heteroclitic counterparts. There was a strong correlation of predicted binding assessed by both scores (Spearmen rho=0.62; p=0.0001) and with respective T2-binding (Spearmen rho=0.66; p<0.0001). Heteroclitic peptides has significantly enhanced predicted binding compared to their native counterparts (Parker Score p<0.00001; Rammensee Score p=0.004, T2-binding p=0.0005) and CTLs generated against heteroclitic peptides had significantly enhanced killing of CD40 activated B-cells pulsed not only with the corresponding heteroclitic peptide (p=0.0003), but also with the native peptide (p=0.04). The binding affinity of low (n=10; FI<0.5) or intermediate binding (n=7; FI>0.6) native peptides did not correlate with specific lysis of peptide pulsed CD40 activated B-cells by CTLs generated against native peptides. Binding affinity of heteroclitic peptides correlated with the ability to induce CTL responses (Spearman rho=0.50; p=0.04). CTLs generated against heteroclitic peptide killed primary CLL cells more effectively than those generated against their native counterparts (p=0.01). Most importantly, the specific lysis of primary tumor cells by successfully generated CTLs was independent of the original binding affinity of the native peptides, both as measured by T2 binding assay (Spearman rho=0.38; p=0.36) and as predicted by the Parker Score (Spearman rho=0.22; p=0.60) or the Rammensee Score (Spearman rho=0.02; p=0.95). Thus, the present study demonstrates recognition of naturally processed Ig-derived peptides even with extremely low binding affinity to MHC class I when higher affinity analogues are used as ‘in vitro’ immunogens. Once CTLs are generated, cytotoxicity appears to be independent of the original binding affinity, suggesting that the rate limiting factor is the ability to generate the immune response, but that once generated, these CTLs have ability to kill tumor cells bearing even very weakly immunogenic peptides. These findings have significant implication for vaccination strategies in B-cell malignancies and warrant in vivo evaluation of this model in CLL.

scholarly journals Converting disulfide bridges in native peptides to stable methylene thioacetals

2016 ◽  
Vol 7 (12) ◽  
pp. 7007-7012 ◽  
Author(s):  
C. M. B. K. Kourra ◽  
N. Cramer
Keyword(s):  
Disulfide Bond ◽  
Disulfide Bridges ◽  
Simple Protocol ◽  
Native Peptides

A mild and simple protocol converts the labile disulfide bond of unprotected native peptides into highly stable methylene thioacetals, annihilating reductive lability and increasing stability.

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