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Mechanical Force and Biomolecules Lecture 2: Overview of biomolecular structure. Ribose vs. Deoxyribose. Throughout: images from online version of “Biochemistry” by Berg, Tymoczko, and Stryer. Sugar phosphate backbone. Nucleic acids: bases. DNA: A, G, T, C RNA: A, G, U , C.
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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