Biomolecules - The Isoelectric Point

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-9"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-pi-calculation-of-amino-acids-primary"><primary style="font-size:24px"> pI Calculation of Amino Acids </primary></h3>
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<main>
<ul>
<li><strong>Amino acids have ionizable groups</strong>: amino (-NH2) and carboxyl (-COOH)</li>
<li><strong>For amino acids with one ionizable group, the pI is the average of its pKa and pKb values</strong>:
pI = (pKa + pKb) / 2</li>
<li><strong>Example</strong>: Glycine (pKa = 2.35), (pKb = 9.78)</li>
<li><strong>For amino acids with two ionizable groups, the pI is calculated using the pKa values of both groups</strong>:
pI = (pKa1 + pKa2) / 2</li>
<li><strong>Example</strong>: Aspartic Acid (pKa1 = 2.09), (pKa2 = 3.86)</li>
<li><strong>For amino acids with three ionizable groups, the pI is determined using the pKa values of all groups</strong>:
pI = (pKa1 + pKa2 + pKa3) / 3</li>
<li><strong>Example</strong>: Histidine (pKa1 = 2.18), (pKa2 = 6.0), (pKa3 = 9.09)</li>
</ul>
</main>
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<footer style = "font-size: 18px">Analysis of Proteins $\rightarrow$ Summary $\rightarrow$ <span style = "color:blue"> pI Calculation of Amino Acids </span> $\rightarrow$ pI Calculation of Peptides and Proteins $\rightarrow$ Application in Protein Separation </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-12"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-determining-protein-pi-with-electrophoretic-mobility-primary"><primary style="font-size:24px"> Determining Protein pI with Electrophoretic Mobility </primary></h3>
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<main>
<ul>
<li>The relative electrophoretic mobility of a protein can help determine its pI</li>
<li>A protein will migrate fastest in an electric field when the pH is significantly different from its pI</li>
<li>By testing the protein’s mobility at different pH values, the pI can be approximated</li>
</ul>
</main>
<hr>
<footer style = "font-size: 18px">pI Calculation of Peptides and Proteins $\rightarrow$ Application in Protein Separation $\rightarrow$ <span style = "color:blue"> Determining Protein pI with Electrophoretic Mobility </span> $\rightarrow$ Calculating pI and Protein Function $\rightarrow$ Effects of pH on Protein Structure </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-16"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-summary-and-review-primary"><primary style="font-size:24px"> Summary and Review </primary></h3>
<hr>
<main>
<ul>
<li>The pI is the pH at which a biomolecule carries no net charge</li>
<li>It is calculated based on the pKa values of ionizable groups in amino acids, peptides, and proteins</li>
<li>The pI is essential in techniques like isoelectric focusing and electrophoresis for protein separation</li>
<li>Understanding the pI can provide insights into protein function and structure</li>
</ul>
</main>
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<footer style = "font-size: 18px">Effects of pH on Protein Structure $\rightarrow$ pI Modifications and Protein Engineering $\rightarrow$ <span style = "color:blue"> Summary and Review </span> $\rightarrow$ Isoelectric Point and Amino Acids $\rightarrow$ Equations for Calculation of pI </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-18"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-equations-for-calculation-of-pi-primary"><primary style="font-size:24px"> Equations for Calculation of pI </primary></h3>
<hr>
<main>
<ul>
<li><strong>Equation</strong>: Calculation of pI for Amino Acids</li>
<li><strong>For amino acids with one ionizable group, the pI is the average of the pKa and pKb values</strong>:
pI = (pKa + pKb) / 2</li>
<li><strong>Equation</strong>: Calculation of pI for Peptides and Proteins</li>
<li>For peptides and proteins, the pI can be calculated using the pI values of the constituent amino acids</li>
</ul>
</main>
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<footer style = "font-size: 18px">Summary and Review $\rightarrow$ Isoelectric Point and Amino Acids $\rightarrow$ <span style = "color:blue"> Equations for Calculation of pI </span> $\rightarrow$ Example of pI Calculation $\rightarrow$ Importance of pI in Protein Separation </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-19"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-example-of-pi-calculation-primary"><primary style="font-size:24px"> Example of pI Calculation </primary></h3>
<hr>
<main>
<ul>
<li>Let’s calculate the pI value for aspartic acid, which has two ionizable groups (carboxyl and amino)</li>
<li>The pKa1 value for the carboxyl group is 2.09</li>
<li>The pKa2 value for the amino group is 9.82</li>
<li><strong>Using Equation 2, we can find the pI</strong>:
pI = (pKa1 + pKa2) / 2
pI = (2.09 + 9.82) / 2
pI ≈ 5.955</li>
<li>Therefore, the pI of aspartic acid is approximately 5.955</li>
</ul>
</main>
<hr>
<footer style = "font-size: 18px">Isoelectric Point and Amino Acids $\rightarrow$ Equations for Calculation of pI $\rightarrow$ <span style = "color:blue"> Example of pI Calculation </span> $\rightarrow$ Importance of pI in Protein Separation $\rightarrow$ Electrophoresis </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-23"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-analysis-of-protein-charge-primary"><primary style="font-size:24px"> Analysis of Protein Charge </primary></h3>
<hr>
<main>
<ul>
<li>Determining the pI of a protein is essential for understanding its charge behavior under different pH conditions</li>
<li><strong>pH < pI</strong>:
<ul>
<li>The protein is positively charged</li>
<li>It migrates towards the cathode in electrophoresis</li>
</ul>
</li>
<li><strong>pH > pI</strong>:
<ul>
<li>The protein is negatively charged</li>
<li>It migrates towards the anode in electrophoresis</li>
</ul>
</li>
<li><strong>pH ≈ pI</strong>:
<ul>
<li>The protein carries no net charge</li>
<li>It remains near the position where it was loaded in electrophoresis</li>
</ul>
</li>
</ul>
</main>
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<footer style = "font-size: 18px">Electrophoresis $\rightarrow$ Isoelectric Focusing $\rightarrow$ <span style = "color:blue"> Analysis of Protein Charge </span> $\rightarrow$ Amino Acid Examples and Their pI Values $\rightarrow$ Amino Acid Examples and Their pI Values </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-26"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-effects-of-ph-on-protein-stability-primary"><primary style="font-size:24px"> Effects of pH on Protein Stability </primary></h3>
<hr>
<main>
<ul>
<li>Extreme pH values can denature proteins and affect their stability</li>
<li>pH values near the pI can also influence protein solubility</li>
<li><strong>Above the pI (pH > pI)</strong>:
<ul>
<li>Protein is negatively charged</li>
<li>Repulsion between protein molecules can lead to aggregation and loss of solubility</li>
</ul>
</li>
</ul>
</main>
<hr>
<footer style = "font-size: 18px">Amino Acid Examples and Their pI Values $\rightarrow$ Amino Acid Examples and Their pI Values $\rightarrow$ <span style = "color:blue"> Effects of pH on Protein Stability </span> $\rightarrow$ Effects of pH on Protein Stability $\rightarrow$ Modifying Protein pI </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-28"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-modifying-protein-pi-primary"><primary style="font-size:24px"> Modifying Protein pI </primary></h3>
<hr>
<main>
<ul>
<li><strong>The pI of a protein can be modified through various techniques</strong>:</li>
<li><strong>Chemical Modification</strong>:
<ul>
<li>Adding or removing functional groups to alter the ionizable residues</li>
<li>May affect protein function</li>
</ul>
</li>
<li><strong>Genetic Engineering</strong>:
<ul>
<li>Mutagenesis techniques to introduce amino acid substitutions</li>
<li>Modifying ionizable residues to change the pI of the protein</li>
</ul>
</li>
<li><strong>pH Adjustment</strong>:
<ul>
<li>Adjusting the pH of the solution to change the charge state of the protein</li>
<li>Can be used to study the effects of different charge states on protein behavior</li>
</ul>
</li>
</ul>
</main>
<hr>
<footer style = "font-size: 18px">Effects of pH on Protein Stability $\rightarrow$ Effects of pH on Protein Stability $\rightarrow$ <span style = "color:blue"> Modifying Protein pI </span> $\rightarrow$ Summary and Review $\rightarrow$  </footer>

<h3 id="success-stylefont-size25px-biomolecules-the-isoelectric-point-success-29"><Success style="font-size:25px"> Biomolecules The Isoelectric Point </Success></h3>
<h3 id="primary-stylefont-size24px-summary-and-review-primary-1"><primary style="font-size:24px"> Summary and Review </primary></h3>
<hr>
<main>
<ul>
<li>The isoelectric point (pI) is the pH at which an amino acid, peptide, or protein carries no net charge</li>
<li>The pI can be calculated based on the pKa values of the ionizable groups</li>
<li>Understanding the pI is essential in protein separation techniques like electrophoresis and isoelectric focusing</li>
<li>The pI affects the charge, solubility, and stability of proteins under different pH conditions</li>
<li>Modifying the pI of proteins can be achieved through chemical or genetic engineering methods and pH adjustment</li>
</ul>
</main>
<hr>
<footer style = "font-size: 18px">Effects of pH on Protein Stability $\rightarrow$ Modifying Protein pI $\rightarrow$ <span style = "color:blue"> Summary and Review </span> $\rightarrow$  $\rightarrow$  </footer>