Conformational study of poly(α‐<scp>L</scp>‐aspartic acid)

Saudek, Vladimı́r; Štokrová, Š.; Schmidt, Pavel

doi:10.1002/bip.360210602

Cited by 25 publications

(16 citation statements)

References 28 publications

(3 reference statements)

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“…The preparation of the samples at various degrees of ionization for the CD measurement has been described in Ref. 12. The deionized samples (a* = 0) were prepared as follows: the polymers were dissolved in HzO and 0.1 mol/L NaOH similarly to those used in the potentiometric titration and acidified with 1 mol/L HC1 to pH about 1; 1 mL of this solution was immediately placed on a quartz disk (for the CD measurement) or AgCl plate (for the ir measurement) and dried in a desiccator over NaOH at atmospheric pressure.…”

Section: Methodsmentioning

confidence: 99%

“…lO We have therefore reinvestigated the conformation of a poly( a -~-A s p ) sample in which 0-bonds were not detected. 12 It was concluded from the results of ir and CD spectroscopy and potentiometric titration that this polymer undergoes a conformational change induced by changes of the degree of ionization, process accompanied by precipitation; the precipitate is highly ordered and probably a-helical. Such a conformational change has not been detected in previous studies, and we have suggestesd that this discrepancy with our results might be due partly to the presence of 0-bonds in the samples investigated.…”

Section: Introductionmentioning

confidence: 99%

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Conformational study of poly(α‐L‐aspartic acid)

1982

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SynopsisThe conformation of poly(a-L-aspartic acid) was investigated on a sample in which @-bonds were not detected. CD and ir spectroscopy showed that poly(a-L-aspartic acid) passes through a conformational change induced by changes of the degree of ionization that is accompanied by precipitation; the precipitate is probably highly helical. The change was also detected by potentiometric titration.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conformational study of poly(α‐L‐aspartic acid)

1982

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“…1660 and ca. 1520 cm À1 ), [48] at least partly in the protonated form (band at 1720 cm À1 )a nd of polysuccinimide (1797 cm À1 marker band). [49] Activation at 190 8Cc auses as light decrease of the former and an increase of the latter.T his is in keeping with the sequence of transformationsp roposed in Scheme 1, because succinimide forms from poly-Asp, but the two phenomenac annot be fully separated.…”

Section: Ftir Spectroscopic Studiesmentioning

confidence: 99%

One Step up the Ladder of Prebiotic Complexity: Formation of Nonrandom Linear Polypeptides from Binary Systems of Amino Acids on Silica

Sakhno

Battistella

Mezzetti

et al. 2018

Chemistry A European J

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Evidence for the formation of linearo ligopeptides with nonrandoms equences from mixtures of amino acids coadsorbed on silica ands ubmitted to as imple thermal activation is presented. The amino acid couples (glutamic acid + leucine)a nd (aspartic acid + valine) were deposited on a fumed silica and submitted to as ingle heating step at moderate temperature. The evolution of the systemsw as characterized by X-ray diffraction, infrared spectroscopy,t hermosgravimetric analysis, HPLC, and electrospray ionizationm ass spectrometry (ESI-MS). Evidence for the formation of amide bonds was found in all systemss tudied. Whilet he products of single aminoa cids activation on silica could be consid-ered as evolutionary dead ends, (glutamic acid + leucine) and, at to somee xtent, (aspartic acid + valine) gave rise to the high yield formation of linear peptides up to the hexamers. Oligopeptides of such length have not been observed beforei ns urface polymerization scenarios (unless the amino acids had been depositedb yc hemical vapor deposition, which is not realistic in ap rebiotic environment). Furthermore,n ot all possible amino acid sequences werep resent in the activation products,w hich is indicative of polymerization selectivity.These resultsare promisingf or origins of life studies because they suggest the emergence of nonrandom biopolymers in as imple prebiotic scenario.

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“…Polyacidic sequences similar in length and acidic amino acid content occur, for example, at the carboxyl termini of HMG-1 and HMG-2 proteins (20) and internally in the sequences encoded by the nucleoplasmin (5) and yeast MCMJ (B.-K. Tye, personal communication) genes and in the Novikoff hepatoma nucleolar nonhistone protein C23 (17). If free from normal protein folding, polyacidic sequences are expected to adopt the charged, disordered, linear configuration observed at neutral pH with poly(Glu) and poly(Asp) (6,25) and with a carboxyl-terminal peptide of HMG-1 protein (3). They would then share a common structure and perhaps a common function(s).…”

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confidence: 99%

Domain structure and functional analysis of the carboxyl-terminal polyacidic sequence of the RAD6 protein of Saccharomyces cerevisiae.

Morrison¹,

Miller²,

Prakash³

1988

Mol. Cell. Biol.

100

116

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The RAD6 gene of Saccharomyces cerevisiae, which is required for normal tolerance of DNA damage and for sporulation, encodes a 172-residue protein whose 23 carboxyl-terminal residues are almost all acidic. We show that this polyacidic sequence appends to RAD6 protein as a polyanionic tail and that its function in vivo does not require stoichiometry of length. RAD6 protein was purified to near homogeneity from a yeast strain carrying a RAD6 overproducing plasmid. Approximately the first 150 residues of RAD6 protein composed a structural domain that was resistant to proteinase K and had a Stokes radius typical of a globular protein of its calculated mass. The carboxyl-terminal polyacidic sequence was sensitive to proteinase K, and it endowed RAD6 protein with an aberrantly large Stokes radius that indicates an asymmetric shape. We deduce that RAD6 protein is monomeric and comprises a globular domain with a freely extending polyacidic tail. We tested the phenotypic effects of partial or complete deletion of the polyacidic sequence, demonstrating the presence of the shortened proteins in the cell by using antibody to RAD6 protein. Removal of the entire polyacidic sequence severely reduced sporulation but only slightly affected survival after UV irradiation or UV-induced mutagenesis. Strains with deletions of all but the first 4 or 15 residues of the polyacidic sequence were phenotypically almost wild type or wild type, respectively. We conclude that the intrinsic activity of RAD6 protein resides in the globular domain, that the polyacidic sequence has a stimulatory or modifying role evident primarily in sporulation, and that only a short section apparently functions as effectively as the entire polyacidic sequence. rad6 mutants of Saccharomyces cerevisiae are extremely sensitive to DNA-damaging agents (4, 9) and are unable to properly replicate a damaged DNA template (22) or process DNA damage into genetic mutations (16,18,21). rad6 mutants also have a meiotic defect resulting in abnormal meiotic recombination (2, 8) and failure to sporulate.The RAD6 DNA sequence (23) predicts a 172-amino-acid protein with a strikingly acidic carboxyl end, where codons 150 to 172 specify the polyacidic sequence Glu-Asp2-MetAsp2-Met-Asp13-Glu-Ala-Asp. Polyacidic sequences similar in length and acidic amino acid content occur, for example, at the carboxyl termini of HMG-1 and HMG-2 proteins (20) and internally in the sequences encoded by the nucleoplasmin (5) and yeast MCMJ (B.-K. Tye, personal communication) genes and in the Novikoff hepatoma nucleolar nonhistone protein C23 (17). If free from normal protein folding, polyacidic sequences are expected to adopt the charged, disordered, linear configuration observed at neutral pH with poly(Glu) and poly(Asp) (6, 25) and with a carboxyl-terminal peptide of HMG-1 protein (3). They would then share a common structure and perhaps a common function(s). Alternatively, a polyacidic sequence might interact with positive charges elsewhere on the protein and form part of the overall folding of th...

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Conformational study of poly(α‐L‐aspartic acid)

Cited by 25 publications

References 28 publications

Conformational study of poly(α‐L‐aspartic acid)

Conformational study of poly(α‐L‐aspartic acid)

One Step up the Ladder of Prebiotic Complexity: Formation of Nonrandom Linear Polypeptides from Binary Systems of Amino Acids on Silica

Domain structure and functional analysis of the carboxyl-terminal polyacidic sequence of the RAD6 protein of Saccharomyces cerevisiae.

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