A Direct Method to Monitor Glutathione Stability in High Concentration Protein Formulations

2021 ◽  
Vol 20 ◽  
Author(s):  
Seth Keever ◽  
Bassam Nakhle ◽  
Bernice Yeung
Keyword(s):  
Protein Stability ◽  
Direct Method ◽  
Antioxidant Properties ◽  
Direct Analysis ◽  
Reversed Phase ◽  
High Concentration ◽  
Analytical Methodology ◽  
Pharmaceutical Protein ◽  
Protein Formulations ◽  
Charged Aerosol

Due to its antioxidant properties and favorable safety profile, glutathione (GSH) finds use in protein formulations by improving overall protein stability. Once degraded, primarily by oxidation into glutathione disulfide (GSSG), the protecting effect of GSH is lost. A simple, direct method using reversed-phase separation and charged-aerosol detection (RP-CAD) to quantitate GSH is described in this paper. The analytical methodology is also capable of monitoring several by-product degradants of GSH, both oxidative and non-oxidative. For high-concentration protein formulations, the method provides direct analysis of GSH and its degradants in the presence of protein at up to 225 mg/mL simply through a dilution of the sample. Quantitation of many amino acids typically included in pharmaceutical protein formulations is also possible. Use of an online diverting valve in the method prevents interference in the detector from the high protein concentration in formulation. Accuracy and effectiveness of this method is demonstrated through monitoring the stability of GSH in high-concentration protein formulations through confirmation of GSH concentration and mass-balance of its loss over time. Monitoring GSH stability in protein formulations is necessary, as GSH concentration is indicative of protein stability.

scholarly journals Direct Analysis in Real Time Mass Spectrometry for the Nondestructive Investigation of Conservation Treatments of Cultural Heritage

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Marcello Manfredi ◽  
Elisa Robotti ◽  
Greg Bearman ◽  
Fenella France ◽  
Elettra Barberis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cultural Heritage ◽  
Real Time ◽  
Direct Method ◽  
High Sensitivity ◽  
Direct Analysis ◽  
Dead Sea ◽  
Ion Source ◽  
Conservation Strategies ◽  
Analytical Methodology

Today the long-term conservation of cultural heritage is a big challenge: often the artworks were subjected to unknown interventions, which eventually were found to be harmful. The noninvasive investigation of the conservation treatments to which they were subjected to is a crucial step in order to undertake the best conservation strategies. We describe here the preliminary results on a quick and direct method for the nondestructive identification of the various interventions of parchment by means of direct analysis in real time (DART) ionization and high-resolution time-of-flight mass spectrometry and chemometrics. The method has been developed for the noninvasive analysis of the Dead Sea Scrolls, one of the most important archaeological discoveries of the 20th century. In this study castor oil and glycerol parchment treatments, prepared on new parchment specimens, were investigated in order to evaluate two different types of operations. The method was able to identify both treatments. In order to investigate the effect of the ion source temperature on the mass spectra, the DART-MS analysis was also carried out at several temperatures. Due to the high sensitivity, simplicity, and no sample preparation requirement, the proposed analytical methodology could help conservators in the challenging analysis of unknown treatments in cultural heritage.

Insights Into Crowding Effects on Protein Stability From a Coarse-Grained Model

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Vincent K. Shen ◽  
Jason K. Cheung ◽  
Jeffrey R. Errington ◽  
Thomas M. Truskett
Keyword(s):  
Protein Stability ◽  
Coarse Grained ◽  
Protein Solutions ◽  
Native State ◽  
High Concentration ◽  
Coarse Grained Model ◽  
Excluded Volume Effects ◽  
Thermodynamic Phase ◽  
Broad Interest ◽  
Liquid Liquid Phase Separation

Proteins aggregate and precipitate from high concentration solutions in a wide variety of problems of natural and technological interest. Consequently, there is a broad interest in developing new ways to model the thermodynamic and kinetic aspects of protein stability in these crowded cellular or solution environments. We use a coarse-grained modeling approach to study the effects of different crowding agents on the conformational equilibria of proteins and the thermodynamic phase behavior of their solutions. At low to moderate protein concentrations, we find that crowding species can either stabilize or destabilize the native state, depending on the strength of their attractive interaction with the proteins. At high protein concentrations, crowders tend to stabilize the native state due to excluded volume effects, irrespective of the strength of the crowder-protein attraction. Crowding agents reduce the tendency of protein solutions to undergo a liquid-liquid phase separation driven by strong protein-protein attractions. The aforementioned equilibrium trends represent, to our knowledge, the first simulation predictions for how the properties of crowding species impact the global thermodynamic stability of proteins and their solutions.

scholarly journals Antioxidant properties, quantification and stability of betalains from pitaya (Hylocereus undatus) peel

2014 ◽  
Vol 45 (2) ◽  
pp. 323-328 ◽  
Author(s):  
Fernanda Robert de Mello ◽  
Claudia Bernardo ◽  
Caroline Odebrecht Dias ◽  
Luciano Gonzaga ◽  
Edna Regina Amante ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Antioxidant Properties ◽  
Raw Material ◽  
High Concentration ◽  
Natural Colorant ◽  
Wide Ph Range ◽  
Hylocereus Undatus ◽  
Ph Range ◽  
Promising Source

Pitaya peel can be used as a raw material for betalains extraction. The aim of this research was to quantify phenolic compounds, antioxidant activity and betalains on pitaya peel. Furthermore, evaluate the betalains stability against various pH conditions and exposure time of heating. The results showed that pitaya peel contains phenolic compounds and presented antioxidant activity. Moreover it showed high concentration of betalains (101.04mg equivalent to betanin. 100g-1) which were stable over a wide pH range (3.2 - 7.0) and were resistant to heating (100oC) up to 10 minutes at pH range from 3.7 to 5.5. Therefore, pitaya peel is a promising source of betalains which can be applied as a natural colorant for food.

Prediction of colloidal stability of high concentration protein formulations

2014 ◽  
Vol 20 (3) ◽  
pp. 367-374 ◽  
Author(s):  
Patrick Garidel ◽  
Alfred Blume ◽  
Michael Wagner
Keyword(s):  
Colloidal Stability ◽  
High Concentration ◽  
Protein Formulations

Direct Analysis of Post-Shakedown Quantities With the STPZ Considering Multi-Parameter Loading

2019 ◽  
Author(s):  
Bastian Vollrath ◽  
Hartwig Hübel
Keyword(s):  
Direct Method ◽  
Kinematic Hardening ◽  
Direct Analysis ◽  
Load Cycle ◽  
Material Behavior ◽  
Plastic Behavior ◽  
Method Effects ◽  
Plastic Shakedown ◽  
Initial Strains ◽  
Incremental Step

Abstract If a structure is subjected to cyclic loading, strain, displacements etc. may accumulate cycle by cycle due to a ratcheting mechanism. Design Codes frequently require strain limits to be satisfied at the end of the specified lifetime of the structure. Usually, this is requested to be done considering all load sets pairwise. However, this leads to the fact that ratcheting cannot be detected, if it occurs only because of multi-parameter loading. Ordinary incremental step-by-step calculations can easily exceed time and hardware resources. This is particularly true for travelling loads, where many load steps are required for one load cycle. As an alternative, the Simplified Theory of Plastic Zones (STPZ) is used in the present paper. Being a direct method, effects from load history are disregarded. The elastic-plastic behavior in the state of either elastic or plastic shakedown is estimated on the basis of purely elastic analyses. Two kinds of linear elastic analyses are to be performed, fictitious elastic analyses for each set of loading, and a number of modified elastic analyses. Few of these analyses are usually sufficient to obtain reasonable estimates of the post-shakedown quantities. Trilinear material behavior is adopted along with kinematic hardening, a Mises yield surface and an associated flow law. The modified elastic analyses are performed making use of modified elastic parameters (Young’s modulus and Poisson’s ratio) in the plastic zone and applying suitably defined initial strains. The results obtained can be improved iteratively. The theory of the method is briefly explained and its application is shown using an example with multi-parameter loading.

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