Proteins molecular stabilization

IV. ROLE OF MOLECULAR CLOSE PACKING ON PROTEIN THERMAL STABILITY... 

Phospholipase C from B. cereus contains two zinc ions per molecule of protein (molecular weight 23 000), the two metal ions being about 5 A apart. The zinc appears to have a particular role in the stabilization of the protein structure.585 Added Zn11 protects the enzyme against denaturation and induces the refolding of the denatured enzyme. Other metals are much less effective than zinc in carrying out this function.586... 

Most peptides and proteins are currently formulated as parenteral formulations because of their poor oral bioavailability. Nevertheless, oral delivery of peptides and proteins would be the preferred route of administration if bioavailability issues could be overcome, as it offers the advantages of convenient, pain-free administration. Although various factors such as permeability, chemical and metabolic stability and gastrointestinal transit time can affect the rate and extent of absorption of orally administered peptides and proteins, molecular size is generally considered the ultimate obstacle [36]. 

A low molecular weight protein, called link protein is also a component of proteoglycan aggregates. Link protein appears to bind simultaneously to hyaluronate and to the hyaluronic acid binding region of core protein, and stabilizes the bond between proteoglycan... 

Chaperones are needed for nucleic acids as well as proteins. The concept that the proper folding of macromolecules may depend on the activities of helper proteins—molecular chaperones—has recently been extended to nucleic acids, notably RNA. As pointed out above, the formation of secondary structures in nucleic acids is an exothermic process (AH is negative), and thus favored by reductions in temperature. If temperature decreases to very low values, nucleic acids may acquire too high a stability of native secondary structure to function well. Moreover, additional regions of secondary structure may form that disrupt normal functions such as transcription and translation. 

In addition to the estimation of protein molecular mass, SDS-CGE is also the common choice for checking the presence of other proteins, protein aggregates, or protein degradation products during characterization, purity, or stability studies. 

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