Native Protein Structure And Stability

The functional properties of food proteins ultimately arise from their unique molecular conformations, which derive from all four levels of structural hierarchy (ie, primary, secondary, tertiary, quaternary) (11). During synthesis on the ribosome, the polypeptide chain, pending subsequent post-translational processing (see section on protein folding, molten globules), adopts a unique molecular conformation traditionally referred to as the native conformation. This particular structure is dictated by the nature and sequence of amino acids in the polypeptide chain and is greatly influenced by solvent effects (12). The folding and resultant (native) conformation of a protein is largely governed by (equilibrium) thermodynamics. The third law of thermodynamics states that

where AG is the change in Gibbs free energy, AH is the change in enthalpy, T is absolute temperature (Kelvin), and AS is the change in entropy. To obey this law, the polypeptide chain must fold into a conformation such that the least amount of free energy is expended in maintaining it. In terms of free energy, hydrophobic effects contribute most to protein folding and stabilization. Hydrophobic interactions are nonspecific and result from the strong hydrogen-bonding properties of water. Nonpolar amino acid residues generally cannot participate in hydrogen-bonding; thus, water molecules surrounding nonpolar residues hydrogen bond with each other to form a highly ordered icelike structure that is associated with unfavorable (ie, low) entropy. The native polypeptide chain, therefore, tends to bury its hydrophobic residues within the interior of the molecule with exclusion of water from this core and to orient its hydrophilic amino acids toward the protein exterior. Exclusion of water from the protein interior

Homemade Pet Food Secrets

Homemade Pet Food Secrets

It is a well known fact that homemade food is always a healthier option for pets when compared to the market packed food. The increasing hazards to the health of the pets have made pet owners stick to containment of commercial pet food. The basic fundamentals of health for human beings are applicable for pets also.

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