Alpha Helix Nucleation by a Simple Cyclic Tetrapeptide

AbstractSynthetic cross-linked collagen-related peptide (CRP-XL) is a glycoprotein VI (GPVI) receptor activator for platelet activation. This triple helical peptide, widely used in platelet function tests, is synthesized and cross-linked through cysteine residues at its N-terminus and C-terminus. Currently, there is only one laboratory, which is capable to produce this valuable peptide for clinical applications. In an attempt to provide a standardized alternative for CRP-XL, we developed a synthetic triple helical collagen peptide (STH-CP) with the same primary sequence as CRP-XL (GPC-(GPO)10-GPCG-amide)3, which was both on the C-terminus and on the N-terminus fixed on a scaffold with a binding side for each of the three peptides. The performance of STH-CP on platelet function was studied using flow cytometry and compared with CRP-XL. We found that platelet activation pattern in response to STH-CP and CRP-XL is similar, although the STH-CP requires sixfold higher concentrations to activate platelets to the same state. The intra-assay percent coefficient of variation of STH-CP and CRP-XL were both < 5% and the interindividual variation measured in 118 individuals for both peptides was around 23 and 21% for αIIbβ3 activation and P-selectin expression, respectively. The STH-CP in ready-to-use reaction mix has lower variation than CRP-XL over 1-year storage. In reference values and seasonal variation study, the platelet activation response showed a strong correlation between STH-CP and CRP-XL.Our findings show that this new STH-CP is a stable and potent platelet GPVI agonist which can induce the same reproducible platelet activation as CRP-XL and that STH-CP can be considered as a good alternative for CRP-XL.

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Evidence for β-turn structure in model peptides reproducing pro-ocytocin/neurophysin proteolytic processing site

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(90)91138-i ◽

1990 ◽

Vol 168 (3) ◽

pp. 1066-1073 ◽

Cited By ~ 21

Author(s):

Mohamed Rholam ◽

Paul Cohen ◽

Nourredine Brakch ◽

Livio Paolillo ◽

Angelo Scatturin ◽

...

Keyword(s):

Proteolytic Processing ◽

Processing Site ◽

Turn Structure ◽

Model Peptides

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Mapping and mutagenesis of the amino-terminal transcriptional repression domain of the Drosophila Krüppel protein.

Molecular and Cellular Biology ◽

10.1128/mcb.14.6.4057 ◽

1994 ◽

Vol 14 (6) ◽

pp. 4057-4066 ◽

Cited By ~ 41

Author(s):

J D Licht ◽

W Hanna-Rose ◽

J C Reddy ◽

M A English ◽

M Ro ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Dna Binding ◽

Transcriptional Repression ◽

Alpha Helix ◽

Amino Acid Sequence Similarity ◽

Protein Fusion ◽

Amino Terminal ◽

N Terminus ◽

Helical Region

We previously demonstrated that the Drosophila Krüppel protein is a transcriptional repressor with separable DNA-binding and transcriptional repression activities. In this study, the minimal amino (N)-terminal repression region of the Krüppel protein was defined by transferring regions of the Krüppel protein to a heterologous DNA-binding protein, the lacI protein. Fusion of a predicted alpha-helical region from amino acids 62 to 92 in the N terminus of the Krüppel protein was sufficient to transfer repression activity. This putative alpha-helix has several hydrophobic surfaces, as well as a glutamine-rich surface. Mutants containing multiple amino acid substitutions of the glutamine residues demonstrated that this putative alpha-helical region is essential for repression activity of a Krüppel protein containing the entire N-terminal and DNA-binding regions. Furthermore, one point mutant with only a single glutamine on this surface altered to lysine abolished the ability of the Krüppel protein to repress, indicating the importance of the amino acid at residue 86 for repression. The N terminus also contained an adjacent activation region localized between amino acids 86 and 117. Finally, in accordance with predictions from primary amino acid sequence similarity, a repression region from the Drosophila even-skipped protein, which was six times more potent than that of the Krüppel protein in the mammalian cells, was characterized. This segment included a hydrophobic stretch of 11 consecutive alanine residues and a proline-rich region.

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A role for amino acids in the cooperative interactions between an alpha helix nucleation site and appended peptides

Peptides ◽

10.1007/978-94-011-0683-2_92 ◽

1994 ◽

pp. 287-289 ◽

Cited By ~ 2

Author(s):

E. Cabezas ◽

L.-C. Chiang ◽

A.C. Satterthwait

Keyword(s):

Amino Acids ◽

Alpha Helix ◽

Nucleation Site ◽

Cooperative Interactions ◽

Helix Nucleation

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Mapping and mutagenesis of the amino-terminal transcriptional repression domain of the Drosophila Krüppel protein

Molecular and Cellular Biology ◽

10.1128/mcb.14.6.4057-4066.1994 ◽

1994 ◽

Vol 14 (6) ◽

pp. 4057-4066

Author(s):

J D Licht ◽

W Hanna-Rose ◽

J C Reddy ◽

M A English ◽

M Ro ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Dna Binding ◽

Transcriptional Repression ◽

Alpha Helix ◽

Amino Acid Sequence Similarity ◽

Protein Fusion ◽

Amino Terminal ◽

N Terminus ◽

Helical Region

We previously demonstrated that the Drosophila Krüppel protein is a transcriptional repressor with separable DNA-binding and transcriptional repression activities. In this study, the minimal amino (N)-terminal repression region of the Krüppel protein was defined by transferring regions of the Krüppel protein to a heterologous DNA-binding protein, the lacI protein. Fusion of a predicted alpha-helical region from amino acids 62 to 92 in the N terminus of the Krüppel protein was sufficient to transfer repression activity. This putative alpha-helix has several hydrophobic surfaces, as well as a glutamine-rich surface. Mutants containing multiple amino acid substitutions of the glutamine residues demonstrated that this putative alpha-helical region is essential for repression activity of a Krüppel protein containing the entire N-terminal and DNA-binding regions. Furthermore, one point mutant with only a single glutamine on this surface altered to lysine abolished the ability of the Krüppel protein to repress, indicating the importance of the amino acid at residue 86 for repression. The N terminus also contained an adjacent activation region localized between amino acids 86 and 117. Finally, in accordance with predictions from primary amino acid sequence similarity, a repression region from the Drosophila even-skipped protein, which was six times more potent than that of the Krüppel protein in the mammalian cells, was characterized. This segment included a hydrophobic stretch of 11 consecutive alanine residues and a proline-rich region.

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ChemInform Abstract: Conformation Control of Model Peptides by Metal Ions. A New Type of Turn Structure Found in ((Boc-Cys-Pro-Leu-Cys-Gly-Ala)Hg).

ChemInform ◽

10.1002/chin.199651177 ◽

2010 ◽

Vol 27 (51) ◽

pp. no-no

Author(s):

T. YAMAMURA ◽

M. ARAI ◽

T. YAMANE ◽

T. UKAI ◽

M. USHIYAMA ◽

...

Keyword(s):

Metal Ions ◽

New Type ◽

Turn Structure ◽

Model Peptides

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Properties and N-terminal sequence of allophycocyanin from the unicellular rhodophyte Cyanidium caldarium

Biochemical Journal ◽

10.1042/bj1630571 ◽

1977 ◽

Vol 163 (3) ◽

pp. 571-581 ◽

Cited By ~ 33

Author(s):

A S Brown ◽

R F Troxler

Keyword(s):

Molecular Weight ◽

Ion Exchange ◽

Phosphate Buffer ◽

Alpha Helix ◽

Ion Exchange Chromatography ◽

Exchange Chromatography ◽

Polyacrylamide Gels ◽

Cyanidium Caldarium ◽

N Terminus ◽

Circular Dichroic

Allophycocyanin from the unicellular rhodophyte Cyanidium caldarium was purified by (NH4)2SO4 fractionation and ion-exchange chromatography on brushite (calcium phosphate) columns and on DEAE-Sephadex A-25 columns. The specific absorption coefficient (A0.1%1cm) at 650nm of purified allophycocyanin was 6.35 in 0.05M-potassium phosphate buffer, pH7.0. Absorption maxima of allophycocyanin occurred at 650, 618 (shoulder), 350 and 275 nm. Circular-dichroic spectra displayed positive-ellipticity bands at 658 and 630 nm and a major negative-ellipticity band at 340nm. Computer analysis of the circular-dichroic spectrum of allophycocyanin from 207 to 243 nm indicated 42% alpha-helix and 58% beta-form. The estimated molecular weight of purified allophycocyanin on calibrated Sephadex G-200 columns at pH7.0. was 196000. Electrophoretic examination of allophycocyanin on sodium dodecyl sulphate/polyacrylamide gels revealed a single band with apparent mol.wt. 16000. The presence of two polypeptide subunits, with nearly the same molecular weight, was revealed on polyacrylamide gels by using a modified electrophoresis buffer. Spectral analysis of the allophycocyanin subunits resolved by ion-exchange chromatography on Bio-Rex 70 columns indicated that a single phycocyanobilin chromophore was present on each polypeptide chain. Treatment of allophycocyanin with 8M-urea (pH3.0) and subsequent removal of urea by dialysis against water yielded a derivative phycobiliprotein with spectroscopic characteristics similar to those of phycocyanin. The original allophycocyanin spectrum was regenerated after incubation in phosphate buffer, pH7.0. Automated sequences analysis of the N-terminus of allophycocyanin showed that (a) the sequences of the two subunits were different from one another and were different from the subunits of phycocyanin from the same alga, (b) the subunits occurred in a molar ratio of 1:1 and (c) the sequences homology at the N-terminus among alpha- and beta-subunits of allophycocyanin from blue-green and red algae approached 90%.

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