The Inactivation of Trypsin by Ultraviolet Light, Ii. The Involvement of Intramolecular Hydrogen Bond Disruption

Augenstine, L. G.; Ghiron, Camillo A.; Grist, Ken L.; Mason, R.

doi:10.1073/pnas.47.11.1733

Cited by 29 publications

(5 citation statements)

References 8 publications

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“…27 In addition, it was found using various methods that the cysteine, tryptophan, tyrosine and phenylalanine are destroyed or altered by UV-irradiation. [29][30][31][32] The data generated by Risi, Dose, 26 Cooper and Davidson, 33 and Perrase, Kondakova 34 concerning amino acid analysis of hydrolysed or irradiated samples show that the amount of other amino acid residues is not significantly influenced. Therefore the assumption can be made that the groups which absorb light energy are also the parts which are mainly photolysed during UV irradiation of proteins.…”

Section: Introductionmentioning

confidence: 98%

“…Probably the first step is the replacement of hydrogen on the benzene ring by hydroxyl groups, according to McLean and Giese . In addition, it was found using various methods that the cysteine, tryptophan, tyrosine and phenylalanine are destroyed or altered by UV‐irradiation . The data generated by Risi, Dose, Cooper and Davidson, and Perrase, Kondakova concerning amino acid analysis of hydrolysed or irradiated samples show that the amount of other amino acid residues is not significantly influenced.…”

Section: Introductionmentioning

confidence: 99%

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Effect of UV-Radiation on the Packaging-Related Properties of Whey Protein Isolate Based Films and Coatings

Schmid

Held

Hammann

et al. 2015

Packag. Technol. Sci.

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The high oxygen barrier properties of whey protein based films and coatings means these materials are of great interest to the food and packaging industry. However, these materials have poor mechanical properties such as the tensile strength, Young's modulus and elongation at break. Up until now, the influence of ultraviolet (UV) radiation on whey protein films has not been reported in the literature. This study thus investigates the influence of UV-radiation on the properties of whey protein based films. UV-irradiated films showed increased tensile strength and a yellowing that was dependent on the radiation time. After irradiation, the films showed no significant change in the barrier properties, Young's modulus or elongation at break. In addition, a protein solubility study was undertaken to characterize and quantify changes in structure-property relationships. The significant decrease in protein solubility in buffer systems which break disulfide and non-covalent bonds indicates that additional molecular interactions arise with increasing radiation dose. This study provides new data for researchers and material developers to tailor the characteristics of whey protein based films according to their intended application and processing. and scientists are working hard to enhance the physical and barrier properties of protein films. According to Wihodo and Moraru, 1 the influence of film formulation and preparation conditions, plasticization, pH alteration, molecular weight adaption and lipid addition on the functional properties of protein films have been extensively investigated and discussed. To modify the properties of proteins, cross-linking techniques induced by heat, chemicals, enzymes and irradiation and the use of nanocomposites have been reported. 1,[9][10][11][12] The formation of covalent interactions such as intermolecular disulfide bonds (heat treatment), ε-(γ-glutamyl)-lysyl bonds (transglutaminase cross-linking) and covalent cross-links between aromatic acids (Ultraviolet (UV) radiation) lead to stabilization of the polymer network and are therefore essential for the mechanical and barrier properties. 13 Recently completed research projects showed that existing whey protein formulations are suitable as barrier layers. [8][9][10]14,15 The influence of UV-radiation on the functional properties and the structureproperty relationships now need to be investigated.According to literature, some research groups 1,7,16-20 have already worked on UV-irradiated protein-based films. Ustunol and Mert 19 irradiated whey protein solution for 3 h with UV light and described increased tensile strength of the cast films but there was no significant difference in the oxygen and water vapour barriers. However, no publications can be found on the influence of UV-irradiation on cast whey protein films.The objective of this study was to investigate if and to what extent the whey protein based barrier layers are influenced by UV irradiation, namely the irradiation time [min] and radiation dose [J/m 2 ]. Of particular inter...

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effect of UV-Radiation on the Packaging-Related Properties of Whey Protein Isolate Based Films and Coatings

Schmid

Held

Hammann

et al. 2015

Packag. Technol. Sci.

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“…If the 12s subunits are held together by noncovalent bonds, the most likely possibility is that ultraviolet light directly or indirectly affects such bonds. A mechanism proposed by Augenstine et al [22], for the inactivation of trypsin by ultraviolet light involves the interaction of an excited disulfide bond "with a neighboring peptide grouping, possibly to extract a proton or hydrogen atom", thus resulting in the disruption of a hydrogen bond. Other reactions, however, may lead to the disruption of hydrogen and/or other non-covalent bonds.…”

Section: Discussionmentioning

confidence: 99%

Effects of Ultraviolet Irradiation (2537 Å) on the Structure of Human Thyroglobulin

Vecchio¹,

Salvatore²,

Dose³

1968

European Journal of Biochemistry

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The effect of in vitro ultraviolet irradiation at 2537 A on the structure of highly purified human thyroglobulin has been investigated by following the ultracentrifugal pattern and the appearance of free sulfhydryl groups in the irradiated protein.Thyroglobulin (19 S) dissociates into two 12 S subunits when it is irradiated with doses of a few hundred Einsteins per mole. The quantum yields of dissociation vary between 0.5 x 10-3 and 2 x depending on the experimental conditions. At higher ultraviolet doses, the protein is partially aggregated and denatured.The extent of dissociation is largely dependent on the ionic strength and the pH of the medium.Doses up to 1,500 Einsteins per mole cause only a partial (3O0iO) splitting of the 19 S molecules, at neutral pH in 0.1 M KCI, whereas a t pH 10 and low salt (T/2= 0.0042), the same dose produces almost complete dissociation into 12 S subunits. Ultraviolet light also causes the rupture of some of the disulfide bonds of native thyroglobulin. On irradiation with several hundred Einsteins per mole protein, as many as 21 -SH groups per molecule can be titrated. The quantum yields for -SH production and destruction of cystine residues are both 0.05.No direct correlation has been found between the extent of dissociation of thyroglobulin and the number of -S-Sbonds cleaved, nor between the reassociation of the 12 S subunits and the reoxidation of -SH groups. It is concluded that two 12 S units present in human thyroglobulin are not linked by interchain disulfide bridges ; the disulfides cleaved by ultraviolet irradiation, however, may play an important role in maintaining the subunit organization of the protein molecule.The major thyroid protein, thyroglobulin (19 S, mol.wt. = 660,000), consists of two half molecules (12 S, mol.wt. = 330,000) which are in turn made up by two polypeptide chains whose sedimentation coefficient, when in a globular form, approximates 6 S [l]. Most of the 12 S subunits are held together in bovine thyroglobulin by non-covalent bonds whereas the 6 S units are linked by a few interchain ____ idine-HC1 [2,6]. Attempts to convert thyroglobulin into globular 6 S species by selectively breaking the interchain disulfide bridges with minimal concentrations ofreducing agent, have so far been uyuccessful [2]. Since ultraviolet irradiation a t 2537 A causes, besides other minor effects, primarily the photolysis of the protein cystine residues [7 -1 I], in the present work we have investigated the effects of this wavelength on the structure of human thyroglobulin.The aim of this study was to learn: a) whether any -S-Slinkages are involved in cross-linking the two 12 S units of human thyroglobulin ; b) whether ultraviolet irradiation at low levels could yield globular 6 S units by selectively breaking interchain disulfide bridges. Furthermore, studies on the effects of ultraviolet light on human thyroglobulin may provide some information on the molecular structure of this protein which is less well characterized than bovine thyroglobulin.A preliminary report o...

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“…Auganstine et al· (114,129), have studied the ultraviolet and ionising It has been found that a general relationship exists between molecular weight and quantum yields for ultraviolet inactivation (123,124).…”

Section: Possible Methods Of Enhancemen T Of Photodynam Ic Actionmentioning

confidence: 99%

Quantum Yield Studies of the Photodynamic Inactivation of Trypsin

Glad¹,

Spikes²

1964

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The Inactivation of Trypsin by Ultraviolet Light, Ii. The Involvement of Intramolecular Hydrogen Bond Disruption

Cited by 29 publications

References 8 publications

Effect of UV-Radiation on the Packaging-Related Properties of Whey Protein Isolate Based Films and Coatings

Effect of UV-Radiation on the Packaging-Related Properties of Whey Protein Isolate Based Films and Coatings

Effects of Ultraviolet Irradiation (2537 Å) on the Structure of Human Thyroglobulin

Quantum Yield Studies of the Photodynamic Inactivation of Trypsin

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