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Protein-based Wood Adhesives Current Trends of Preparation and Application
Published in Zhongqi He, Bio-based Wood Adhesives, 2017
Birendra B. Adhikari, Pooran Appadu, Michael Chae, David C. Bressler
Sodium dodecyl sulfate and sodium dodecyl benzene sulfonate are both detergents and denaturing agents, and they have been used to chemically treat various protein sources. Sodium dodecyl sulfate binds with protein molecules disrupting secondary, tertiary, and quaternary structures. This disruption is believed to expose functional groups due to rapid changes in the conformation of proteins (Tanford, 1968). It is expected that sodium dodecyl benzene sulfonate will have the same effect. The use of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate generally led to an improvement in the adhesive properties of the proteins (Cheng et al., 2013; Huang and Sun, 2000a; Zhong et al., 2003). For example, the use of sodium dodecyl sulfate led to an increase in tensile strength from 130 to 200 lb/in2 for adhesives developed from cottonseed protein (Cheng et al., 2013). Huang and Sun (2000) studied the effect of the concentration of sodium dodecyl benzene sulfonate (0-3 percentage) on the dry shear strength and soaked shear strength of adhesives developed from soy protein. Concentrations of sodium dodecyl benzene sulfonate from 0.5-1 percentage improved both the dry and soaked shear strengths of walnut specimens bonded with the sodium dodecyl benzene sulfonate-treated soy protein. The use of 1 percentage sodium dodecyl benzene sulfonate resulted in an increase in dry shear strength of walnut wood specimens from 25 to 48 kg/cm2. However, the use of 3 percentage concentrations of sodium dodecyl benzene sulfonate generally did not impact dry and soaked shear strengths (Huang and Sun, 2000a).
Formulation of Protein- and Peptide-Based Parenteral Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Gaozhong Zhu, Pierre O. Souillac
Many factors can cause denaturation, including heat, freezing, extreme pHs, organic solvents, high salt concentration, lyophilization, surface adsorption, and mechanical stress. These denaturing conditions disrupt a protein’s higher order structure, which is held together by intramolecular forces including hydrogen bonding, salt bridges or electrostatic forces, hydrophobic interactions, and van der Waals forces.
Enzyme Catalysis
Published in Harvey W. Blanch, Douglas S. Clark, Biochemical Engineering, 1997
Harvey W. Blanch, Douglas S. Clark
Inclusion bodies can facilitate protein purification. Because of their size and density, inclusion bodies can be separated from other cellular components by low-speed centrifugation (speeds as low as 500g are sometimes sufficient but values of 5000-12,000g are more generally used). Aggregation also protects the protein product from proteolytic degradation. (Indeed, inclusion bodies have been likened to proteins encased in stainless steel shells!) On the other hand, inclusion bodies present the problem of solubilizing the recombinant protein. The situation is somewhat similar to developing a method for isolating egg albumin from hard-boiled eggs. Common solubilization agents include 5-8 M guanidinium chloride, 6-8M urea, detergents, alkaline pH(>9.0), and organic solvents. Note that these are conditions which typically denature native proteins. If covalent disulfide bonds exist in the aggregates, thiol reagents can be used in conjuction with denaturants. Following solubilization and unfolding of the protein, the denaturant must be diluted or removed by dialysis so that the protein can refold to its native, active form. The complexity of the solubilization-reactivation process varies with different proteins; key variables in published protocols include time, pH, ionic strength, the choice of denaturant, and the ratio of denaturant to protein. In most cases the recovery of biologically active proteins is incomplete.
Production, purification and characterization of a novel antithrombotic and anticoagulant serine protease from food grade microorganism Neurospora crassa
Published in Preparative Biochemistry & Biotechnology, 2022
Yajie Duan, Priti Katrolia, Ailing Zhong, Narasimha Kumar Kopparapu
Effect of metal ions on fibrinolytic activity was also studied. Metal ions such as Cu2+, Na+, and Zn2+ enhanced the fibrinolytic activity, while catalysis was strongly compromised by Fe2+. Similar results were reported from Pleurotus ostreatus and Xylaria curta where Fe2+ reduced fibrinolytic activities.[31,39] Based on their inhibitor specificity, fibrinolytic enzymes can be grouped as serine proteases, metalloproteases, and others. In this study, serine protease inhibitors such as PMSF, SBTI and aprotinin completely inhibited fibrinolytic activity, which indicates the purified enzyme could be a serine protease. Metalloprotease inhibitor EDTA did not inhibit the activity, which indicates metal ions are not involved in catalysis. Effect of other reagents on fibrinolytic activity was also studied. 0.25% β-mercaptoethanol (130%) enhanced the activity of the enzyme, which is similar to another study.[34] Denaturing agents such as 8 M urea (54%) and 0.25% SDS (100%) reduced the fibrinolytic activity, which showed they might have denatured the enzyme. Denaturing agents may denature the protein and change its structure which results in decreased or complete loss of activity. Similar results were reported for fibrinolytic enzyme from Agrocybe aegerita.[36]