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This lecture provides an in-depth look at the structural differences between ribose and deoxyribose in biomolecules. With a focus on nucleic acids, proteins, and amino acids, explore how these components play a crucial role in the formation of complex biomolecular structures. Images from "Biochemistry" by Berg, Tymoczko, and Stryer enhance the understanding of sugar phosphate backbones, nucleic acid bases, double helix formation, and protein structures. Gain insights into the diverse physical properties of amino acids and how they contribute to the vast array of protein structures. Learn about the hierarchy of protein structures from primary to quaternary levels and the significance of secondary structures like alpha helices and beta sheets.
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Mechanical Force and BiomoleculesLecture 2:Overview of biomolecular structure
Ribose vs. Deoxyribose Throughout: images from online version of “Biochemistry” by Berg, Tymoczko, and Stryer
Nucleic acids: bases DNA: A, G, T, C RNA: A, G, U, C
Two chains with complementary sequences will basepair, and coil around each other to form a double helix Watson-Crick Basepairing joins 2 chains
Double-helix is asymmetric (major and minor groove); each groove has unique pattern of H-bonding- permits bp-specific binding to grooves (e.g. by other N.A., protein)
Single-stranded nucleic acids can fold into complex structures This is a Ribozyme- an RNA structure that can act as an enzyme, and catalyze reactions
Amino acids are chiral From Berg et al, Biochemistry (NCBI books website)
Simple aliphatic: Glycine: R = Hydrogen Alanine: R = methyl Small, so not much h-phobic effect Side chains 2
Larger Aliphatic; Large h-phobic effect 6
Proline: also aliphatic, but not averse to H2O Cyclization makes poly-proline chains very rigid 7
Aromatic rings Tyr: reactive hydroxyl Trp and Tyr: strongly absorb UV light (commonly used to quantify protein concentration) 10
Cysteine Sulfur can form covalent di-sulfide bonds; important for labelling! 13
Basic side chains: (+) charge, hydrophilic pK = 6.5 (His), 12.0 (arg), 10.0 (Lys) 16
Acidic 20
Large variety in physical properties of amino acids leads to a large variety of protein structures.Typically, these are classified in a hierarchy of:Primary = a.a. sequenceSecondary = local folded structuresTertiary = Globular arrangement of chainQuaternary = Association of multiple chains
Secondary structure: Alpha helix (typically right-handed) Amine at position n H-bonds with CO at position n+4
Anti-parallel Secondary: Beta sheet Parallel
Tertiary structure: Arrangement of local motifs into compact, globular structure:
Quaternary structure: Arrangement of multiple chains into a multi-meric complex