In biochemistry, the native state of a protein is its properly folded and assembled form with operative structure and function. The native state of a protein needs all four levels of biomolecular structure, with secondary to quaternary structure formed by weak interactions along the covalently-bonded backbone. Proteins in their natural state with intact structure that is not altered by heat, chemicals, enzyme reaction, or other denaturants are named "native proteins".
Compared to recombinant protein generated using protein engineering techniques, native protein are obtained from proper organisms and are unaltered by outer factors such as heat, chemicals and enzyme reaction, and retain their naturally folded state. With natural structure and functional activities, native proteins are used in a wide range of applications such as protein functional assays, ELISA kits, Western Blot, Immunoprecipitation, etc.
The native state of a protein is defined as the ensemble of compact conformations, forming under folding conditions in vivo or in vitro. In native state, the protein is stable and active. In biophysics, the native state of a protein is defined by a low amount of entropy with a relatively low intramolecular enthalpy. In native state, all atoms of the protein are kept by mutual interaction in a well-defined geometry. The native state of a protein can be distinguished from a molten globule by distances measured by NMR.
Altering the folding conditions such as increasing temperature, changing buffer pH or adding denaturant can result in a much more complex and heterogeneous ensemble of protein conformations, which are named the denatured states. In addition, different unfolding conditions induce different denatured states. Strong unfolding conditions induce high percentage of secondary structure changes. Proteins in denatured states can be detected with relatively high conformational entropy and intramolecular enthalpy, because of the loss of native interactions.
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Ven 16 Déc 2016 - 7:15