Sikander Aqeel

BIO ALGEBRA OF LIVING ORGANISMS

Sep 16th 2016, 11:11 am

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(Bio Mathematical Lab of Sikander Aqeel)

CHAPTER [3] PROTEINS

Proteins

Charge and Chemical Properties of Amino acids and Proteins,

An understanding of protein requires knowledge of the ionizable side chain groups of the common amino acids, these ionizable groups common to proteins and amino acids, the acid form of the respective ionizable groups are on the left of the sum, while the respective properties base are on the right side, characteristic of the acid form is that nitrogen-containing groups are positively charged, whereas the acid forms that contain oxygen and sulfur atoms are natural,

Separation of Amino acids and Protein Based on pI Value

The techniques of electrophoresis isoelectric focusing and ion exchange chromatography are some of the more important techniques for the study of biological molecules based on charge,

In electrophoresis an ampholyte (protein, Peptide, Amino acid) in a solution buffered at a particular pH is placed in an electric field, depending on the relationship of the buffer pH to the pI of the molecule, the molecule will either move toward the (-) or the anode (+), or remain stationary (pH = pI)

An example of classical apparatus for protein electrophoresis is apparatus consist of a U-tube in which is placed a protein solution, followed by a buffer solution carefully layered over the protein solution, the migration of the protein is observed with an optical device that measures changes in the refractive index of the solution as the protein migrates toward the anode,

This apparatus historically led to the separation and operational classification of protein in human plasma,

For the plasma protein separation, the solution is buffered at pH 8.6, which is at a pH substantially above the pI of the important plasma protein, the proteins are negatively charged and move toward the positive electric pole,

(9/17/2016)

The peaks in order of their rate of migration, related to the order of their pI value, are the albumin, the a1, a2 and B-globulins, fibrinogen, and the Y1 and Y2-globulin, these peaks represent tens to hundreds of individually different plasma proteins that have a similar migration rate to the anode at pH 8.6, their rate of migration under these experimental condition gives an experimental value for these protein that is widely used for purposes of their identification and classification,

More sophisticated procedures for electrophoresis utilize polymer gels, starch, or paper as an electrophoresis support, the inert supports are saturated with buffer solution, an electric field is applied across the buffered support, and the proteins migrate in the support toward a charged pole,

For example the pI is the average of the two pKa value that form the boundaries of the zwitterions form, and the pI is calculated as follows

pKa COOH + pKa NH3

pI = _____________________ = 6.00

pH and pI

1 = Cathode = (-pH), 8.6

2 = Anode = (+pI), 1000 micro-charge

= a2 / b2 = c2

= a2 (Anode) / b2 (Cathode) = c2

= a2 (1000) / b2 (8.6) = c2

= a / b = (1000000) / b (73.96) = c2

= a / b = 13520.82 = c2

= a / b = 13520.82 / 116.27 = 116.28