The net charge and isoelectric pH (pI) of a protein depend on the content of ionizable groups and their pK values. Ribonuclease Sa (RNase Sa) is an acidic protein with a pI = 3.5 that contains no Lys residues. By replacing Asp and Glu residues on the surface of RNase Sa with Lys residues, we have created a 3K variant (D1K, D17K, E41K) with a pI = 6.4 and a 5K variant (3K + D25K, E74K) with a pI = 10.2. We show that pI values estimated using pK values based on model compound data can be in error by >1 pH unit, and suggest how the estimation can be improved. For RNase Sa and the 3K and 5K variants, the solubility, activity, and stability have been measured as a function of pH. We find that the pH of minimum solubility varies with the pI of the protein, but that the pH of maximum activity and the pH of maximum stability do not.
Thermodynamic investigations of proteins. I. Standard functions for proteins with lysozyme as an example
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Quantitative analysis of the contribution of Glu46 and Asn98 to the guanosine specificity of ribonuclease T1
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Contribution of histidine residues to the conformational stability of ribonuclease T1 and mutant Glu-58----Ala
pH dependence of the urea and guanidine hydrochloride denaturation of ribonuclease A and ribonuclease T1
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pH-induced denaturation of proteins: a single salt bridge contributes 3-5 kcal/mol to the free energy of folding of T4 lysozyme
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Polypeptide amino acid composition and isoelectric point. II. Comparison between experiment and theory
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Simplified methods for pKa and acid pH-dependent stability estimation in proteins: removing dielectric and counterion boundaries
Buried, charged, non-ion-paired aspartic acid 76 contributes favorably to the conformational stability of ribonuclease T1
Charge-charge interactions influence the denatured state ensemble and contribute to protein stability
pH dependence of stability of staphylococcal nuclease: evidence of substantial electrostatic interactions in the denatured state
Calibrative approaches to protein solubility modeling of a mutant series using physicochemical descriptors
The correlation of RNase A enzymatic activity with the changes in the distance between Nepsilon2-His12 and N delta1-His119 upon addition of stabilizing and destabilizing salts
Long- and short-range electrostatic interactions affect the rheology of highly concentrated antibody solutions
Increased alkalotolerant and thermostable ribonuclease (RNase) production from alkaliphilic Streptomyces sp. M49-1 by optimizing the growth conditions using response surface methodology
Stabilization of the cold shock protein CspB from Bacillus subtilis by evolutionary optimization of Coulombic interactions
Carbonic anhydrase as a model for biophysical and physical-organic studies of proteins and protein-ligand binding
SCHEMA-designed variants of human Arginase I and II reveal sequence elements important to stability and catalysis
Revisiting ligand-induced conformational changes in proteins: essence, advancements, implications and future challenges
Salt-induced stabilization of apoflavodoxin at neutral pH is mediated through cation-specific effects
Improved sensitivity of the nano ultra-high performance liquid chromatography-tandem mass spectrometric analysis of low-concentrated neuropeptides by reducing aspecific adsorption and optimizing the injection solvent
Arginine and lysine reduce the high viscosity of serum albumin solutions for pharmaceutical injection
De novo design of protein-protein interactions through modification of inter-molecular helix-helix interface residues
Stable nanoparticles prepared by heating electrostatic complexes of whey protein isolate-dextran conjugate and chondroitin sulfate
Limitation of tuning the antibody-antigen reaction by changing the value of pH and its consequence for hyperthermia
High-throughput thermal stability analysis of a monoclonal antibody by attenuated total reflection FT-IR spectroscopic imaging
Carboxyl pK(a) values, ion pairs, hydrogen bonding, and the pH-dependence of folding the hyperthermophile proteins Sac7d and Sso7d
Amino acid contribution to protein solubility: Asp, Glu, and Ser contribute more favorably than the other hydrophilic amino acids in RNase Sa
Structure of RNase Sa2 complexes with mononucleotides--new aspects of catalytic reaction and substrate recognition
Solution structure and thermal stability of ribosomal protein L30e from hyperthermophilic archaeon Thermococcus celer
Solubility-dependent structural formation of a 25-residue, natively unfolded protein, induced by addition of a seven-residue peptide fragment
Thermodynamic parameters for salt-induced reversible protein precipitation from automated microscale experiments
Urea denatured state ensembles contain extensive secondary structure that is increased in hydrophobic proteins
A detailed representation of electrostatic energy in prediction of sequence and pH dependence of protein stability
Intra- versus intermolecular interactions in monellin: contribution of surface charges to protein assembly
Characterization of a novel high-pH-tolerant laccase-like multicopper oxidase and its sequence diversity in Thioalkalivibrio sp
Unveiling the optimal parameters for cellulolytic characteristics of Talaromyces verruculosus SGMNPf3 and its secretory enzymes
Strategies to reduce aspecific adsorption of peptides and proteins in liquid chromatography-mass spectrometry based bioanalyses: an overview
Electrostatic contributions to T4 lysozyme stability: solvent-exposed charges versus semi-buried salt bridges
Concentration-dependent changes in apparent diffusion coefficients as indicator for colloidal stability of protein solutions
Engineering increased thermostability in the GH-10 endo-1,4-β-xylanase from Thermoascus aurantiacus CBMAI 756
Protein Thermostability Is Owing to Their Preferences to Non-Polar Smaller Volume Amino Acids, Variations in Residual Physico-Chemical Properties and More Salt-Bridges
On-line capillary isoelectric focusing hyphenated to native electrospray ionization mass spectrometry for the characterization of interferon-γ and variants
Physicochemical characterization of colored soluble protein fractions extracted from Spirulina ( Spirulina platensis)
Polyglutamine expansion in ataxin-3 does not affect protein stability: implications for misfolding and disease
Why are proteins charged? Networks of charge-charge interactions in proteins measured by charge ladders and capillary electrophoresis
Genetic and chemical approaches for surface charge engineering of enzymes and their applicability in biocatalysis: A review
High-throughput screening and stability optimization of anti-streptavidin IgG1 and IgG2 formulations
NADPH biosensor-based identification of an alcohol dehydrogenase variant with improved catalytic properties caused by a single charge reversal at the protein surface
Numerical calculations of the pH of maximal protein stability. The effect of the sequence composition and three-dimensional structure
Sarconesin: Sarconesiopsis magellanica Blowfly Larval Excretions and Secretions With Antibacterial Properties
pH-Dependent Aggregation in Intrinsically Disordered Proteins Is Determined by Charge and Lipophilicity
Activity profile of innate immune-related enzymes and bactericidal of freshwater fish epidermal mucus extract at different pH
A novel hyperthermophilic methylglyoxal synthase: molecular dynamic analysis on the regional fluctuations.
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