The Protein Man's Blog | A Discussion of Protein Research

Protein Storage and Stability

What are Proteins?

As one of the multifarious macromolecules, proteins are complex and crucial for cellular functions. Proteins are polymers built of monomer subunits called amino acids connected by a specific type of covalent bond known as a peptide bond. The properties of the protein depend on the type of amino acids present in them. Although the primary structure of the protein comprises of the amino acid sequence, the functional properties of the protein crucially rely on the three-dimensional or tertiary structure. Similarly, protein modifications for e.g., glycosylation, phosphorylation, may change the properties and function of the protein. These modifications alter the local conformation and mediate folding or stability as well as drive proteins to different cellular compartments. Proteins also display remarkable variability in terms of structure and flexibility depending upon their folding patterns. Some proteins are relatively rigid hence can function as structural meshes or connective lines. Proteins with reversible conformational changes (polymerization or depolymerization) are crucial for protein-protein interaction, growth and the transmission of information from cell to cell or within the cell.

The BCA assay (bicinchoninic acid assay) developed by Paul K. Smith et al. has become one of the most widely used protein assays since its introduction in 1985. The advantages offered by the assay help to explain the popularity and widespread use over other protein assays. The advantages of the BCA include:

Purified and commercial antibodies are routinely stored in buffers that contain the proteins bovine serum albumin (BSA) and gelatin as these act as stabilizers during long term storage.  The presence of 0.2-1% (2-10mg/ml) BSA and/or gelatin help to stabilize antibody solutions that are less than 1mg/ml during long term storage.  For the majority of immunodetection techniques (ELISA, Western blotting, immunoprecipitation) the presence of the stabilizers do not interfere with these immunodetection techniques and can be used without clean up.  

Bacteria are as interesting as they are diverse. Though tiny, these unicellular life forms make huge contributions to many systems and cycles. From helping break down food in your intestine; to making the molecular assist in all three of the carbon, phosphorus, and nitrogen cycles -- these little bacteria can accomplish big things. Unsurprisingly, bacteria are model organisms for research. Not only because of their diversity, but also because they are easily contained and reproduce quickly. When using bacteria for research, it is important to understand and track rates of bacterial growth within a sample.