Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

30. Peptides and Proteins

Tertiary Protein Structure

Organic Chemistry

30. Peptides and Proteins

Tertiary Protein Structure

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Multiple Choice

Which of the following amino acid pairs are the most likely to form hydrogen bonds?

Cysteine – cysteine

Lysine – glutamate

Serine – threonine

Leucine – valine

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Verified step by step guidance

Understand the concept of hydrogen bonding: Hydrogen bonds are weak interactions that occur between a hydrogen atom covalently bonded to an electronegative atom (like oxygen or nitrogen) and another electronegative atom.

Identify functional groups capable of hydrogen bonding: In amino acids, the hydroxyl (-OH), amino (-NH2), and carboxyl (-COOH) groups are common sites for hydrogen bonding.

Analyze the side chains of the given amino acids: Serine and threonine both contain hydroxyl groups in their side chains, which can participate in hydrogen bonding.

Compare with other pairs: Cysteine has a thiol group (-SH), which is less effective in hydrogen bonding compared to hydroxyl groups. Lysine has an amino group, and glutamate has a carboxyl group, which can form hydrogen bonds, but their interaction is more ionic. Leucine and valine have nonpolar side chains, making them unlikely to form hydrogen bonds.

Conclude that serine and threonine are the most likely to form hydrogen bonds due to the presence of hydroxyl groups in their side chains, which are highly effective in forming hydrogen bonds.