Pi, isoelectric point

Immunostaining was decreased in some cell types that the nuclear components were extracted, pis, isoelectric points of antigen proteins. 

Table 2.1.1 (continued) Some properties of the most relevant amino acids. pi isoelectric point m.w. Molecular weight, ... 

Figure 4.2. Model polypeptide of 20 amino acids. The three-letter and one-letter abbreviations for amino acids are shown. Ionizable amino acids (-R) are shown as positively or negatively charged in bold. Note that the amino-terminal and carboxy-terminal ends are charged. All charges contribute to an overall charge state of the protein at a specific pH. The pi (isoelectric point) is the pH at which a proteins carries no net charge. The pi is helpful in classifying proteins as acidic, neutral, or basic. The addition of posttranslational modifications can also add charges to proteins and greatly affect the pi value.

Isoelectric Focusing. The principle of the isoelectric focusing method is to focus proteins at their respective pis (isoelectric points) in a stable... 

Write formulas that show how the structure of valylglycine changes as the pH of the solution changes from 1 to 10. Estimate the pi (isoelectric point) of this dipeptide. 

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