Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

4. Protein Structure

Isoelectric Point of a Peptide

Biochemistry

4. Protein Structure

Isoelectric Point of a Peptide

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Multiple Choice

Calculate the approximate pI of the peptide: C-G-E-K.

3.08

5.71

6.05

9.63

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Verified step by step guidance

Identify the ionizable groups in the peptide C-G-E-K. These include the N-terminus, the C-terminus, and the side chains of the amino acids Cysteine (C), Glutamic acid (E), and Lysine (K).

Determine the pKa values for each ionizable group. Typically, the pKa values are approximately: N-terminus (~9.0), C-terminus (~2.0), Cysteine (~8.3), Glutamic acid (~4.1), and Lysine (~10.5).

List the pKa values in ascending order: 2.0 (C-terminus), 4.1 (Glutamic acid), 8.3 (Cysteine), 9.0 (N-terminus), 10.5 (Lysine).

To find the isoelectric point (pI), identify the pKa values between which the peptide has a net charge of zero. This typically involves averaging the pKa values around the neutral charge state.

Calculate the pI by averaging the two pKa values that correspond to the transition from a positive to a neutral charge and from a neutral to a negative charge. In this case, average the pKa values of the N-terminus and Cysteine.