Protein Permeability Lab Report

The noncovalent interactions that maintain the three-dimensional structure of proteins are weak. Considering this, they are easily disrupted. The unfolding of protein is called denaturation. [1] Denaturation happens because the bonding interactions which are responsible for the secondary structure (hydrogen bonds to amides) and tertiary structure undergo disruption. There are different types of bonding interactions between “side chains” in tertiary structure. This includes hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions which may be disrupted. Therefore a variety of physical and chemical agents can cause denaturation.
There are several ways for a protein to be denatured. One is heat. Vibrations within

[7] It determines the percent and type of secondary structure. In this method, left (L) and right (R) circularly polarized light is made to pass through a sample. Elliptically polarized light are then produced because of the interaction of optically active molecules with L and R circularly polarized light. Proteins are optically active chiral molecules. They become UV and CD-active due to the asymmetric nature of the peptide bond. When the protein backbone folds into a sheet, random coil, or helix, it is reflected in the far-UV CD spectrum of the protein. In CD spectroscopy, proteins and peptides with characteristic alpha-helical or beta-sheet structures have known profiles. Random coil also posses their own characteristic peak. When a protein undergoes unfolding, it shifts from a helical to a random-coil structure. [2]
In dealing with dilute solutions, ƿ  p˳ therefore, the relative viscosity becomes t/ t˳. The specific viscosity of dilute solutions (ŋsp) is (t/ t˳)-1. However, reduced viscosity which is the specific viscosity divided by the concentration of the solution is usually the one sought after. It is used for the assessment of the effect of unfolding and reduction of disulfide bonds on the tertiary structure of the protein. [2] The equation is as

The flow time (t) is equal to kŋƿ, where k is the viscometer constant, ŋ is the viscosity, and ƿ is the density of the solution. Through experiment, the determination of viscosity can be done by measuring the flow time in a viscometer. It should be taken in consideration that changes in viscosity are always relative to that of the native protein and that of the solvent matrix or blank. The ratio of the viscosity (ŋ) of the sample to the viscosity of the blank (ŋ˳) is equal to the relative viscosity (ŋ/ ŋ˳). The relative viscosity is given by the following equation with the use of the same viscometer for both solution and solvent. [2] The equation is as