Journal ArticleDOI
Monitoring of Demasking of Peptide Bonds During Proteolysis by Analysis of the Apparent Spectral Shift of Intrinsic Protein Fluorescence
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TLDR
Demasking of peptide bonds during proteolysis of β-casein and β-lactoglobulin by trypsin was monitored by the measurement of the overall spectral shift of intrinsic protein fluorescence, showing that the fluorescence shift can be attributed to the demasking stage.Abstract:
Demasking of peptide bonds during proteolysis of β-casein and β-lactoglobulin by trypsin was monitored by the measurement of the overall spectral shift of intrinsic protein fluorescence. A clear shift of the apparent emission maxima from approximately 340–345 nm to 355–360 nm during proteolysis was observed, with a time course, which follows protein degradation and structural opening. In contrast to procedures using extrinsic fluorescence labels, this label-free procedure does not bear the risk of structural alterations. It is easy to perform, fast, and has a relatively high accuracy of determination. Proteolysis was modelled as simple two-step process with consecutive demasking and hydrolysis stages. It was shown that the fluorescence shift can be attributed to the demasking stage. Formally, kinetics of the peptide bond demasking obeys a first-order kinetic law. Both the theoretical simulations and experiment are in accordance giving the similar dependences of the hydrolysis degree on the degree of peptide bond demasking.read more
Citations
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Journal ArticleDOI
Proteolytically-induced changes of secondary structural protein conformation of bovine serum albumin monitored by Fourier transform infrared (FT-IR) and UV-circular dichroism spectroscopy
TL;DR: Both spectroscopic techniques demonstrate that there are similar but less spectral changes of BSA for the trypsin attack than for α-chymotrypsin although the substrate/enzyme ratio is taken the same.
Journal ArticleDOI
Changes in structural characteristics of antioxidative soy protein hydrolysates resulting from scavenging of hydroxyl radicals.
TL;DR: Oxidatively modified SPHs had a lower intrinsic fluorescence intensity but similar solubility when compared to nonoxidized samples, suggesting structural changes due to •OH stress may impact the ingredient interaction and functionality ofSPHs in food products.
Journal ArticleDOI
Effect of ultrasonic pretreatment on kinetics of gelatin hydrolysis by collagenase and its mechanism.
TL;DR: The current results suggest that ultrasound can be potentially applied to stimulate the production efficiency of gelatin peptides, mainly due to its effects on modification of protein structures.
Book ChapterDOI
Bioanalytical Aspects in Enzymatic Protein Hydrolysis of By-Products
Sileshi Gizachew Wubshet,Diana Lindberg,Eva Veiseth-Kent,Kenneth Aase Kristoffersen,Ulrike Böcker,Kathryn E. Washburn,Nils Kristian Afseth +6 more
TL;DR: This chapter covers the classical analytical methodologies used to measure important process and quality parameters, as well as emerging approaches of using rapid spectroscopic techniques as process control and optimization tools.
Journal ArticleDOI
Quantification of two-step proteolysis model with consecutive demasking and hydrolysis of peptide bonds using casein hydrolysis by chymotrypsin
TL;DR: Parameters of a two-step model were calculated and it was found that kd is lower than the hydrolysis rate constants for specific sites consisting of aromatic amino acid residues, and at least a half of peptide bonds is initially masked in casein.
References
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TL;DR: This book describes the fundamental aspects of fluorescence, the biochemical applications of this methodology, and the instrumentation used in fluorescence spectroscopy.
Journal ArticleDOI
Spectrophotometric Assay Using o-Phthaldialdehyde for Determination of Proteolysis in Milk and Isolated Milk Proteins
TL;DR: The o-phthaldialdehyde Spectrophotometric (OPS) as discussed by the authors was developed and characterized for measurement of proteolysis of milk proteins in buffered solutions or in milk.
Journal ArticleDOI
Mechanisms of Tryptophan Fluorescence Shifts in Proteins
James T. Vivian,Patrik R. Callis +1 more
TL;DR: This study predicted the fluorescence wavelengths of 19 tryptophans in 16 proteins using a hybrid quantum mechanical-classical molecular dynamics method with the assumption that only electrostatic interactions of thetryptophan ring electron density with the surrounding protein and solvent affect the transition energy.
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Advanced dairy chemistry
TL;DR: Advanced dairy chemistry, Advanced dairy chemistry , مرکز فناوری اطلاعات و اصاع رسانی, کδاوρزی
Journal ArticleDOI
Fluorescein isothiocyanate-labeled casein assay for proteolytic enzymes.
TL;DR: A simple inexpensive sensitive protease assay was developed using soluble fluorescein isothiocyanate (FITC)-labeled casein, which resembles natural substrates of most proteases.