Proteins physicochemical properties

Base-catalyzed racemization reactions may occur in any of the amino acids except achiral glycine (Gly) to yield residues in proteins with mixtures of L- and D-configurations. The a-methine hydrogen is removed to form a carbanion intermediate (Fig. 6.26b). The degree of stabilization of this intermediate controls the rate of this reaction. Racemization generally alters the proteins physicochemical properties and biological activity. Also, racemization generates... 

Fatty acylation targets a wide range of cellular proteins which encompass kinases, GTPases, heterotrimeric G proteins, cytokines, and phosphatases (1-3). The role of fatty acylation is to regulate these proteins physicochemical properties and spatial localization in cells. In doing so, fatty acylation controls the activation and deactivation of signaling pathways. Fatty acylation involves the enzyme-catalyzed addition of 14-carbon (myristoylation) or 16-carbon (palmitoylation) fatty acid chains to cellular proteins via amide- or thioester bonds, respectively. 

Dmg distribution into tissue reservoirs depends on the physicochemical properties of the dmg. Tissue reservoirs include fat, bone, and the principal body organs. Access of dmgs to these reservoirs depends on partition coefficient, charge or degree of ionization at physiological pH, and extent of protein binding. Thus, lipophilic molecules accumulate in fat reservoirs and this accumulation can alter considerably both the duration and the concentration—response curves of dmg action. Some dmgs may accumulate selectively in defined tissues, for example, the tetracycline antibiotics in bone (see Antibiotics,tetracyclines). 

In subsequent studies attempting to find a correlation of physicochemical properties and antimicrobial activity, other parameters have been employed, such as Hammett O values, electronic distribution calculated by molecular orbital methods, spectral characteristics, and hydrophobicity constants. No new insight on the role of physiochemical properties of the sulfonamides has resulted. Acid dissociation appears to play a predominant role, since it affects aqueous solubiUty, partition coefficient and transport across membranes, protein binding, tubular secretion, and reabsorption in the kidneys. An exhaustive discussion of these studies has been provided (10). 

Table 3 shows some physicochemical properties used as international GA quality parameters, for example moisture, total ash content, volatile matter and internal energy, with reference to gums taken from Acacia Senegal species in Sudan (FAO, 1990, Larson Bromley, 1991). The physicochemical properties of GA may vary depending on the origin and age of trees, the exudation time, the storage type, and climate. The moisture content facilitates the solubility of GA carbohydrate hydrophilic and hydrophobic proteins. The total ash content is used to determine the critical levels of foreign matter, insoluble matter in... 

The distribution of a drug in the body is largely driven by its physicochemical properties and in part for some compounds by the contribution of transporter proteins [17]. By using the Oie-Tozer equation and estimates for ionization (pfCj). plasma protein binding (PPB) and lipophilicity (log quite robust predictions for the volume of distribution at steady state (Vdss), often within 2-fold of the observed value, can be made [18]. 

Protein-Based Surfactants Synthesis, Physicochemical Properties, and Applications, edited by Ifendu A. Nnanna and JidingXia... 

Rickard, E. C., Strohl, M. M., and Nielsen, R. G., Correlation of electrophoretic mobilities from capillary electrophoresis with physicochemical properties of proteins and peptides, Anal. Biochem., 197, 197, 1991. 

The use of data concerning the physicochemical properties of chemicals (e.g., stability, solubility, pH, octanol-water partition coefficient, and protein binding). 

Sugimoto T, Itagaki K, Irie K (2008) Design and physicochemical properties of new fluorescent ligands of protein kinase C isozymes focused on CH/7t interaction. Bioorg Med Chem 16 650-657... 

This chapter will cover recent developments in the design of diverse and protein family-targeted libraries, their physicochemical properties, and contemporary methods for screening them. 

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