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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The protein journal 1 (1982), S. 1-1 
    ISSN: 1573-4943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The protein journal 1 (1982), S. 3-4 
    ISSN: 1573-4943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The protein journal 1 (1982), S. 59-69 
    ISSN: 1573-4943
    Keywords: horse liver alcohol dehydrogenase ; isozymes ; substrate specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Horse liver contains previously unrecognized isozymes of alcohol dehydrogenase. In contrast to the molecular forms identified up to now, under the conditions employed these variants migrate toward the anode on starch gel electrophoresis and were separated from the cathodic isozymes by DEAE-cellulose chromatography. They were then purified on agarose-hexane-AMP. Their physicochemical and compositional characteristics are similar to those x alcohol dehydrogenases from human liver. Like these and similar ones from simian liver, they retain most of their activity in the presence of10 mm 4-methylpyrazole, oxidize short-chain primary alcohols very poorly, and appear to prefer longer chain primary alcohols and ω-hydroxy fatty acids as substrates.
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  • 4
    ISSN: 1573-4943
    Keywords: sulfhydryl reagents ; l-cysteine ; chemical modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple, general scheme for the synthesis of sulfhydryl-specific alkyl alkanethiolsulfonate (RSSO2R′) reagents where R′ is methyl, has been developed. Two new reagents, methyl aminoethanethiolsulfonate (2) and methyl benzylthiolsulfonate (3) were synthesized. These were used to modify stoichiometrically and selectively under mild conditions the sulfhydryl groups ofN-acetyl-l-cysteine ethyl ester (4),N-acetyl-l-cysteinep-nitroanilide (7), glutathione, and the A chain of bovine insulin. The corresponding β-S-(β-aminoethanethiol) and β-S-(benzylthiol) derivatives ofl-cysteine and of the peptides were afforded. The characteristics and significance of these reactions and products are discussed.
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  • 5
    ISSN: 1573-4943
    Keywords: protein denaturation, reconstructive ; protein structure, reorganization of ; circular dichroism of proteins ; protein conformation ; pokeweed mitogens Pa2, Pa4 ; lectin (Wistaria floribunda) ; lutropin ; Bence Jones protein ; sodium dodecyl sulfate, effect on protein conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The factors determining the onset and extent of reconstructive denaturation of proteins were considered by comparing circular dichroism (CD) data of seven proteins and previously published findings. The effects of sodium dodecyl sulfate (SDS) on the conformation of the following proteins were tested: lysozyme, the mitogens fromPhytolacca americana (fractions Pa2 and Pa4), lectin fromWistaria floribunda, ovine lutropin, a Bence Jones protein, and histone H2B. While the helix content of lysozyme was raised by SDS slightly, in the Bence Jones protein andW. floribunda lectin it increased from near zero to about 25–30%. In histone H2B the helix content was raised by SDS even to about 48%. However, no clear indication of helix formation could be observed in the mitogens and lutropin, even at low pH or 2.0–2.5. The tertiary structure of the proteins was perturbed by SDS. It was concluded that the reorganization of secondary structure of the proteins was favored by the following factors: (1) presence of helicogenic amino acid sequences in the protein, (2) availability of positively charged sites of the basic amino acids for interactions with the dodecyl ion, (3) absence of a large surplus of negatively charged sites on the surface of protein, and (4) absence of extensive disulfide cross-linking within the macromolecule. Both hydrophobic and electrostatic interactions occur in reconstructive denaturation, and the newly formed helices are stabilized by hydrophobic shielding by the alkyl chains of the alkyl sulfate.
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  • 6
    ISSN: 1573-4943
    Keywords: protein conformation, conformational parameters of ; long-range interactions ; medium-range interactions ; short-range interactions ; amino acids, nature of ; amino acid pairs, nature of ; amino acid pairs, distances within
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A statistical analysis of protein conformations in terms of the distance between residues, represented by their Cα atoms, is presented. We consider four factors that contribute to the determination of the distanced i,i+k between a given pair ofith and(i+k)th residues in the native conformation of a globular protein: (1) the distancek along the chain, (2) the size of the protein, (3) the conformational states of theith to(i+k)th residues, and (4) the amino acid types of the and(i+k)th residues. In order to account for the dependence on the distancek along the chain, the statistics are taken for three ranges, viz., short, medium, and long ranges (k≤8; 9≤k≤20; andk≥21; respectively). In the statistics of short-range distances, a mean distanceD k and its standard deviationS k are calculated for each value ofk, with and without taking into account the conformational states of all residues fromi toi+k (factors 1 and 3). As an Appendix, the relations for converting from the distances between residues into other conformational parameters are discussed. In the statistics of long-range distances, a reduced distanced* ij (the actual distance divided by the radius of gyration) is used to scale the data so that they become independent of protein size, and then a mean reduced distanceD l (aμ, aν) and its standard deviation σl (aμ, aν) are calculated for each amino acid pair (aμ, aν) (factors 2 and 4). The effect of the neighboring residues along the chain on the value of the distanced* ij is explored by a linear regression analysis between the actual reduced distanced* ij and the mean value over theD l for all possible pairs of residues in the two segments of the (i−2)th to the (i+2)th and the (j−2)th to the (j+2)th residues. The effect is assessed in terms of the tangentA l (aμ, aν) of the calculated regression line for each amino acid pair (aμ, aν). In the statistics of medium-range distances, only factors 1 and 4 are considered, to simplify the analysis. The scaled distanced i,i+k † =(d i,i+k -D k )/S k is used to eliminate the dependence onk, the distance along the chain. The propertiesD m (aμ, aν), σm (aμ, aν) andA m (aμ, aν) corresponding toD l (aμ, aν), σl (aμ, aν), andA l (aμ, aν), and also calculated for each amino acid pair (aμ, aν). The results are interpreted as follows: the smaller values ofD l (aμ, aν) andD m (aμ, aν) indicate a preference of the pair (aμ, aν) for a contact (e.g., pairs between hydrophobic amino acids, and pairs of Cys with aromatic amino acids), and the larger values of these quantities indicate a preference for distant mutual location (e.g., pairs between strong hydrophilic amino acids); the smaller values of σl (aμ, aν) and σm (aμ, aν) indicate a strong preference for either contact or noncontact (e.g., pairs between hydrophobic amino acids, and pairs between strong hydrophobic and hydrophilic amino acids, respectively), and the larger values of these quantities indicate the ambivalent/neutral nature of the preference for contact and noncontact (e.g., pairs containing Ser or Thr); the smaller values ofA l (aμ, aν) andA m (aμ, aν) indicate that the distance of an (aμ, aν) pair is determined independently of the amino acid character of the neighboring residues along the chain (e.g., some pairs of Cys or Met with other amino acids) and the larger values of these quantities indicare that such amino acid character contributes strongly to the determination of the distance (e.g., pairs containing Ser or Thr, and pairs between amino acids with small side chains). The difference between the statistics for the long- and medium-range distances is also discussed; the former reflect the difference between the hydrophobic and hydrophilic character of the residues, but the latter cannot be easily interpretable only in terms of hydrophobicity and hydrophilicity. The data analyzed here are used in the optimization of an object function to compute protein conformation in a subsequent paper.
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  • 7
    ISSN: 1573-4943
    Keywords: purine nucleotide derivatives ; affinity labels ; chemical modification of enzymes ; nucleotide affinity labels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two new adenosine analogs, 2′-(2-bromoethyl) adenosine monophosphate and 3′-(2-bromoethyl) adenosine monophosphate, were synthesized, purified by semipreparative high-pressure liquid chromatography, and completely characterized. A new synthesis of 5′-(2-bromoethyl) adenosine monophosphate is presented which facilitates the preparation of radioactive reagent with label either in the ethyl group or the purine ring of the nucleotide derivative. The reactive moiety of these derivatives, a bromoalkyl group, has the ability to react with the nucleophilic side chains of several amino acids. The second-order, pH-independent rate constants for reaction with the side chains of the amino acids cysteine, lysine, histidine, and tyrosine were determined as 3×10−4, 6×10−6, 3×10−7, and 〈1×10−7 M−1 sec−1, respectively. These data could be use in estimating the rate enhancement observed in modification of a protein by these affinity-labeling reagents. 5′-(S-(2-hydroxyethyl)cysteine) adenosine monophosphate, the derivative expected from exhaustive digestion of protein in which a cysteinyl residue is modified by 5′-(2-bromoethyl) adenosine monophosphate, and S-2-hydroxyethyl)cysteine, the derivative anticipated upon acid hydrolysis of such a modified protein, were synthesized, characterized, and their elution positions from an amino acid analyzer determined. These bromoethyl AMP derivatives are potential affinity labels for enzymes that bind 2′-, 3′-, or 5′-nucleotides such as TPN, coenzyme A, or ADP, respectively.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The protein journal 1 (1982), S. i 
    ISSN: 1573-4943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4943
    Keywords: protein disulfide bonds ; reductive alkylation ; soybean trypsin inhibitor (Kunitz) ; UV absorption spectra ; fluorescence spectra ; S-β-2-quinolylethylation ; cyst(e)ine determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Disulfide bonds in soybean trypsin inhibitor (Kunitz) were simultaneously reduced and alkylated using tri-n-butylphosphine and 2-vinylquinoline at pH 7.6 in 0.11 M Tris-4.4 M urea, 41% ethanol. The resulting S-β-2-quinolylethylated protein (2-QE-STI) has a new absorption peak at 315–318 nm. Its quinoline fluorescence can be excited above 310 nm independently of intrinsic protein fluorescence. Free 2-quinolylethylcysteine (2-QEC) shows unexpectedly weak fluorescence. Quinoline absorption in 2-QEC and 2-QE-STI changes with pH. The apparentpK values determined spectrophotometrically are near 5 for 2-QEC and 3 for 2-QE-STI. Fluorescence decreased with increasing pH and in the presence of chloride ions. Both structural and charge effects thus appear to influence the absorption and fluorescence of the quinoline group. Corrected fluorescence emission (excited at 316 nm) of neutral 2-QE-STI diluted in 0.1 N H2SO4 was directly proportional to concentration in the range 0.4–8 μm 2-QEC. The 2-QEC content of the protein derivative determined by UV absorption at pH 1.5 was in agreement with the expected value of four residues per mole. Fluorescence measurements ofS-2-quinolylethylated proteins may be especially useful as a sensitive, specific assay for cyst(e)ine residues.
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  • 10
    ISSN: 1573-4943
    Keywords: DABITC: thin layer chromatography ; sequence identification and thiohydantoin by-products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 4-N,N-Dimethylaminoazobenzene 4′-isothiocyanate degradations permit sensitive and fast manual sequence analysis, but assignments of some residues are difficult. Hydrophobic residues, especially leucine and isoleucine, are badly resolved on polyamide thin-layer chromatography. Differently colored by-products have been described before for a few labile residues, but it is now shown that most residues can give rise to characteristic by-products. These have different colors and chromatographic properties, depending on the nature of the parent residue. Thus, two to three sets of spots characterize each residue, giving multiple identification with increased reliability. Although variable and dependent on chemicals and conditions, by-products are often prominent after conversion with 50% trifluoroacetic acid, and can be utilized to improve the identifications.
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