Phenolic Hydroxyl Ionization in Proteins. II. Ribonuclease<sup>1a</sup>

Tanford, Charles; Hauenstein, Jack D.; Rands, David G.

doi:10.1021/ja01629a001

Cited by 252 publications

(92 citation statements)

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“…This conclusion is based upon the appearance of a weak broad band in the UV absorbance spectrum (not shown) near 300 nm and a relative increase in absorbance at 250 nm, both of which are similar to changes that accompany alkaline titration of RNase A when exposed Tyr residues become ionized. 33 In the near-UV CD spectra (Figure 8), the partially resolved band at 283 nm is attributed to the exposed Tyr residue(s) of the enzyme. 32 Therefore, the 10% decrease in the intensity of this band caused by the 9-day incubation with 10% formalin may also reflect changes affecting the Tyr residues.…”

Section: Effect Of Formalin On the Secondary And Tertiary Structure Omentioning

confidence: 99%

Modeling formalin fixation and antigen retrieval with bovine pancreatic ribonuclease A: I—Structural and functional alterations

Rait

O'Leary

Mason

2004

Laboratory Investigation

129

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Understanding the chemistry of protein modification by formaldehyde is central to developing improved methods to recover proteins from formalin-fixed paraffin-embedded tissues for proteomic analysis and to improve protein immunoreactivity for immunohistochemical studies. We used biophysical techniques to investigate the effects of formaldehyde treatment on bovine pancreatic ribonuclease A (RNase A). Treatment of RNase A with formaldehyde was shown by gel electrophoresis to lead to the rapid formation of intra-and intermolecular protein cross-links. Thermal studies revealed that these protein cross-links significantly increased the thermal denaturation temperature of RNase A preparations. Analysis of formaldehyde-treated RNase A oligomers isolated by gel chromatography revealed that intramolecular protein cross-links are primarily responsible for the increase in protein thermostability. Formaldehyde treatment also lowered the isoelectric point of the enzyme from 9.45 to the 6.0-7.4 range. Optical spectroscopic studies demonstrated that the formaldehyde-induced modifications did not significantly alter the secondary or tertiary structure of RNase A. Heating formaldehyde-treated RNase A at 651C resulted in a significant reversal of the protein intra-and intermolecular cross-links and led to a partial restoration of enzymatic activity.

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Section: Effect Of Formalin On the Secondary And Tertiary Structure Omentioning

confidence: 99%

Modeling formalin fixation and antigen retrieval with bovine pancreatic ribonuclease A: I—Structural and functional alterations

Rait

O'Leary

Mason

2004

Laboratory Investigation

129

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“…The interpeptide hydrogen bonds of the a-helix and /3-sheet by contrast were backed by 20 years of intense thought and structural studies using model compounds: Hager's biography of Pauling gives a good account of his preoccupation with the subject (Hager, 1995) Examination of reviews and published symposia during this period indicate little interest in the hydrophobic theory for protein ~~ ~ 4Looking back on my own activities at the time, I became an enthusiast for hydrophobic bonds after Kauzmann's first paper, with no apparent need for an interpretation in terms of water structure and not even an awareness of the entropy/enthalpy problem (Tanford, 1957). The probable reason is that our laboratory work at the time had yielded gross anomalies for the acid/base titration of tyrosyl side chains of ribonuclease (Tanford et al, 1955), for which burial in a hypothetical oily molecular interior, inaccessible to water, provided a tailor-made explanation, whereas interpretation in terms of hydrogen bonds between amino acid side chains was hugely implausible.…”

Section: General Acceptancementioning

confidence: 99%

How protein chemists learned about the hydrophobic factor

1997

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It is generally accepted today that the hydrophobic force is the dominant energetic factor that leads to the folding of polypeptide chains into compact globular entities. This principle was first explicitly introduced to protein chemists in 1938 by Irving Langmuir, past master in the application of hydrophobicity to other problems, and was enthusiastically endorsed by J.D. Bemal. But both proposal and endorsement came in the course of a debate about a quite different structural principle, the so-called "cyclol hypothesis" proposed by D. Wrinch, which soon proved to be theoretically and experimentally unsupportable. Being a more tangible idea, directly expressed in structural terms, the cyclol hypothesis received more attention than the hydrophobic principle and the latter never actually entered the mainstream of protein science until 1959, when it was thrust into the limelight in a lucid review by W. Kauzmann. A theoretical paper by H.S. Frank and M. Evans, not itself related to protein folding, probably played a major role in the acceptance of the hydrophobicity concept by protein chemists because it provided a crude but tangible picture of the origin of hydrophobicity per se in terms of water structure.

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“…The rate constant gradually increased with increase of pH from 6.8 to 10, where the amount of the ionized phenolic species of tyrosine increased. This finding can be attributed to the fact that the ionized form of tyrosine is a stronger absorbing group 17 and possesses higher quantum yield than the unionized form in the oxidation reaction. 18 Furthermore, higher reaction rate was observed in Tyr-Arg, Lys-Tyr-Lys, and tyrosine than in Gly-Tyr, Glu-Tyr, and NAc-Tyr.…”

Section: Photo-oxidation Of Model Tyrosyl Peptides and Effect Of Phmentioning

confidence: 99%

“…Exposure to light can further accelerate the oxidation reaction. 14,16 Solution pH has a significant effect on tyrosine oxidation because the pK a of the tyrosyl group is 10.1, 17 and the ionized tyrosine is more susceptible to oxidation than the un-ionized form. 12,18 Many adjuvants are added to parenteral formulations to stabilize proteins.…”

Section: Introductionmentioning

confidence: 99%

The effect of neighboring amino acid residues and solution environment on the oxidative stability of tyrosine in small peptides

Zhang

Kalonia

2007

AAPS PharmSciTech

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The effects of neighboring residues and formulation variables on tyrosine oxidation were investigated in model dipeptides (glysyl tyrosine, N-acetyl tyrosine, glutamyl tyrosine, and tyrosyl arginine) and tripeptide (lysyl tyrosyl lysine). The tyrosyl peptides were oxidized by light under alkaline conditions by a zero-order reaction. The rate of the photoreaction was dependent on tyrosyl pK a , which was perturbed by the presence of neighboring charged amino acid residues. The strength of light exposure, oxygen headspace, and the presence of cationic surfactant, cetyltrimethylammonia chloride had a significant effect on the kinetics of tyrosyl photooxidation. Tyrosine and model tyrosyl peptides were also oxidized by hydrogen peroxide/metal ions at neutral pH. Metal-catalyzed oxidation followed first-order kinetics. Adjacent negatively charged amino acids accelerated tyrosine oxidation owing to affinity of the negative charges to metalions, whereas positively charged amino acid residues disfavored the reaction. The oxidation of tyrosine in peptides was greatly affected by the presence of adjacent charged residues, and the extent of the effect depended on the solution environment.

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Phenolic Hydroxyl Ionization in Proteins. II. Ribonuclease^1a

Cited by 252 publications

References 0 publications

Modeling formalin fixation and antigen retrieval with bovine pancreatic ribonuclease A: I—Structural and functional alterations

Modeling formalin fixation and antigen retrieval with bovine pancreatic ribonuclease A: I—Structural and functional alterations

How protein chemists learned about the hydrophobic factor

The effect of neighboring amino acid residues and solution environment on the oxidative stability of tyrosine in small peptides

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Phenolic Hydroxyl Ionization in Proteins. II. Ribonuclease1a

Cited by 252 publications

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Modeling formalin fixation and antigen retrieval with bovine pancreatic ribonuclease A: I—Structural and functional alterations

Modeling formalin fixation and antigen retrieval with bovine pancreatic ribonuclease A: I—Structural and functional alterations

How protein chemists learned about the hydrophobic factor

The effect of neighboring amino acid residues and solution environment on the oxidative stability of tyrosine in small peptides

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Product

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Phenolic Hydroxyl Ionization in Proteins. II. Ribonuclease^1a