Energy Transfer in Proteins

Augenstein, Leroy; Nagchaudhuri, J

doi:10.1038/2031145a0

Cited by 32 publications

(11 citation statements)

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“…However, with these assumptions the values for ,B-B calculated from the data for RNAse and insulin (0.032 and 0.064, Tyr+Phe respectively) varied by a factor of two (11). This discrepancy between proteins is not surprising since it is known from phosphorescence studies that energy transfer among the aromatic residues depends critically on the internal environment of individual proteins (9,24,25,26). Further, we have investigated whether a constant set of values would be obtained for RNAse irradiated at different wavelengths large.…”

Section: Discussionmentioning

confidence: 99%

“…To explain this demonstrated specificity of cystine disruption, Augenstein et all predicted that energy transfer to aromatic residues either immediately adjacent to, and/or bonded to a cystine could cause the latter's disruption (8), and Augenstein and Chaudhuri anticipated that significant electronic interactions occur between some tyrosines and cystines in RNAse on the basis of their spectroscopic studies (9). Recently Cowgill has interpreted the fluorescence quenching in simple compounds containing disulfide and sulfhydryl groups as evidence for interaction between aromatic residues, and these groupings (10).…”

Section: Introductionmentioning

confidence: 99%

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Photochemical Yields in Ribonuclease and Oxidized Glutathione Irradiated at Different Wavelengths in the Ultraviolet

Rathinasamy¹,

Augenstein²

1968

Biophysical Journal

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The quantum yields for the disruption of various amino acids in glutathione and ribonuclease by 229, 254, 265, and 280 nm UV photons have been determined. The results of the measurements on the destruction of tyrosine and histidine and the loss of enzymic function in RNAse and the disruption of cystine in both compounds lead to the following conclusions: (a) The photodestruction of some and perhaps many constituent amino acid residues does not cause RNAse inactivation. (b) Contrary to the basic premise of proposals made by other authors, the photochemical yields of constituent residues in a protein are not the same as that for the same amino acids in solution alone-the difference is a function of the exciting wavelength. Further, the extent of histidine destruction varies by a large factor among three proteins. (c) Consistent with previous predictions, the present results show that photons absorbed in the aromatic residues of RNAse cause the disruption of cystines elsewhere in the enzyme. (d) Although cystine disruption appears to be the most prevalent mode of RNAse inactivation by photons of the four wavelengths studied, some of the minor mechanisms leading to loss of enzymic function may vary with the UV energy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photochemical Yields in Ribonuclease and Oxidized Glutathione Irradiated at Different Wavelengths in the Ultraviolet

Rathinasamy¹,

Augenstein²

1968

Biophysical Journal

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“…It seems likely that the major tyrosyl-phosphorescence changes are due to a change in the state of a tyrosyl residue. Having most, or all, of the observed signals arise from a single residue is not surprising since it is known that in many proteins the tyrosyl contribution to the phosphorescence emission is not always observed (12)(13)(14). The phosphorescence changes in the presence of substrate or inhibitor serve as a strong indication for the participation of the tyrosyl residue in the active center of the enzyme.…”

Section: Discussionmentioning

confidence: 99%

The Role of a Tyrosyl Residue in the Mechanism of Action of Carboxypeptidase B: Luminescence Studies

Shaklai

Zisapel

Sokolovsky

1973

Proc. Natl. Acad. Sci. U.S.A.

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The luminescence spectra of carboxypeptidase B indicate specific differences between the zinc and apoenzyme due to the state of tyrosyl residues presumably at the active site. These differences disappear when enzyme-substrate or enzyme-inhibitor co6mplexes are formed, suggesting that they may reflect the interaction of a tyrosyl residue in the native enzyme with the catalytically essential zinc atom. An interpretation of the role of that tyrosyl residue in the mechanism of action of carboxypeptidase B is presented.Chemical modifications have implicated a chemically hyperreactive tyrosyl residue in the function of carboxypeptidase B. Thus, nitration of the enzyme (1) markedly decreases the enzymic activity towards both basic and nonbasic substrates (2). These changes have been correlated with the nitration of active-site tyrosyl residues. Alkylation (3), iodination (5), acetylation (4), succinylation (6), and coupling with a diazonium salt (6) also involve tyrosyl residues with analogous catalytic consequences. The luminescence spectra of proteins provides an intrinsic sensitive signal of changes in stereochemical relationships directly related to the aromatic aminoacid side chains, especially tryptophan and tyrosine. Changes in the microenvironment of these residues may be thus observed especially in a protein like carboxypeptidase B possessing a reactive tyrosyl residue. We have, therefore, examined the luminescence properties of this enzyme. The results indicate differences in the tyrosyl state between the apo-and the zinc enzyme. These differences disappear on formation of enzyme-substrate or enzyme-inhibitor complexes. METHODSApocarboxypeptidase B was prepared from porcine carboxypeptidase B [(Code COBC) Worthington Biochemical Corp.] by dialysis against multiple changes of 4 mM 1,10-phenanthroline in 0.01 M sodium acetate buffer (pH 5.5) followed by dialysis against the same buffer without phenanthroline, and finally against 0.05 M Tris HCl-0.1 M NaCl at the desired pH. The apoenzyme was reconstituted by dialysis against 0.05 M Tris HCl-0.1 M NaCl (pH 7.5) buffer containing 1 mM zinc sulphate (Merck Co.) followed by dialysis against metal-free buffer.The metal content was determined by atomic absorption spectroscopy (Varian Techtron model AA5) and found to be 0.96-0.98 g-atom of Zn in the reconstituted enzyme and less than 0.03 g-atom of Zn in the apoenzyme. Enzymatic * To whom to address correspondence. activities were estimated with basic and nonbasic peptide and ester substrates (2).Fluorescence spectra were measured with a HitachiPerkin-Elmer spectrofluorometer model MPF-2. Phosphorescence measurements were performed with the same instrument, equipped with a phosphorescence attachment. Phosphorescence signals were obtained by use of a chopper of the Becquerell type rotating at 25 Hz to cut off short-lived signals (fluorescence and stray-light). Emission was observed at 900 to the incident beam. All spectra given are uncorrected for instrument response. Decay curves were obtained by use of a Te...

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“…For example, the ability of certain residues in a protein to transfer energy or undergo intersystem crossing was found to be a function of their environments and the exciting wavelength (19,20). Specifically, the phosphorescence/fluorescence (P/F) ratios and the fraction of phosphorescence from tryptophan and tyrosine residues varied from protein to protein, and changed when 240nm UV was used for excitation rather than 280-nm (21). Further, the phosphorescence from tyrosine at 77°K is different for this amino acid in frozen solution, in lyophilized powders, in homopolypeptides, and in the protein ribonuclease (22).…”

Section: The Influence Of the Molecular Environmentmentioning

confidence: 99%

“…Further, the mean values cited above "bridge the gap" between the values of 4 sec and 2.2 sec reported previously for NUV-and X-ray-induced phosphorescence. These observations are of particular interest since X-ray-induced phosphorescence from trypsin resembles that from tyrosine in decay time, peak wavelength, and thermal coefficients (4); whereas NUV excitation leads to phosphorescence which appears to originate from the constituent tryptophan residues (19, 21,22). It is hoped that more sensitive equipment now being constructed will allow us to disperse the VUV-initiated phosphorescence so as to determine whether the difference in spectroscopic behavior between NUV-and X-rayexcited trypsin reflects primarily the effects of excitations to higher-lying states, ionizations, or slow electrons produced by the latter radiations (5).…”

Section: The Influence Of the Molecular Environmentmentioning

confidence: 99%

Vacuum Ultraviolet Studies on the Nature of the Radiation Inactivation of Trypsin

Yeargers¹,

Augenstein²

1968

Biophysical Journal

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Trypsin, in powder form and in frozen D(2)O-glucose solutions, at temperatures from 100 degrees to 300 degrees K, was excited with vacuum ultraviolet and near ultraviolet radiation to determine how absorbed photon energy is partitioned into radiative, nonradiative and/or inactivating processes; at 300 degrees K most of the absorbed energy is not reemitted, so that it (0.98-0.99 for excitation at 120 nm and 0.75-0.90 at 280 nm) is potentially available for inactivation. Since the effects of excitation wavelength and temperature on the emission quenching yields are generally different from those on the inactivation yields of dry trypsin, the mere retention of quenched energy by an enzyme does not necessarily lead to its inactivation. Thus, as predicted previously, the radiation inactivation of trypsin must proceed by rather specific mechanisms which undoubtedly depend upon environment-sensitive processes, since the nature of the molecular environment can modify the partitioning of energy so significantly; for example, there are differences in the phosphorescence-to-fluorescence ratio, in the activation energy for quenching, and in the lifetimes and kinetics of the decay of phosphorescence when trypsin in frozen glasses and dry trypsin are excited by various wavelengths of ultraviolet radiation.

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Energy Transfer in Proteins

Cited by 32 publications

References 4 publications

Photochemical Yields in Ribonuclease and Oxidized Glutathione Irradiated at Different Wavelengths in the Ultraviolet

Photochemical Yields in Ribonuclease and Oxidized Glutathione Irradiated at Different Wavelengths in the Ultraviolet

The Role of a Tyrosyl Residue in the Mechanism of Action of Carboxypeptidase B: Luminescence Studies

Vacuum Ultraviolet Studies on the Nature of the Radiation Inactivation of Trypsin

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