1.1 Biomolecule basics Flashcards
Which stereochemical configuration is predominant in nature?
R stereochemistry / L configuration
Is glycine a chiral molecule?
No, achiral, two same side chains (H) at alpha C
What are the amino acid types?
- Hydrophobic
- Acids
- Amides
- Bases
- Aromatics
- Alcohols
- Thiol / tiolether
Selenocysteine (21st)
Explain peptide bond formation
What are Φ (phi) and Ψ (psi) bonds in a peptide? How are they different from the peptide bond?
Φ (phi) and Ψ (psi) bonds are free to rotate because they are stabilised by free e pair of N - π bond can be created
What strcutures are formed in secondary protein structure? Which atoms interact to form what bonds?
Repeated α-helices and β-sheets are formed by H-bonds between backbone atoms
How are α-helices formed?
- COOH is H-bond acceptor
- N is H-bond donor
- forms between n and n+4
Why is proline known as helix breaker?
Cyclic side chain of proline has no N to donate H-bond
How are β-sheets formed?
- COOH is H-bond acceptor
- N is H-bond donor
- forms between antiparallel β-pleats to form β-sheet (can form parallel - less stable)
How are tertiary protein structures formed?
By side chain interactions of DOMAINS:
- hydrophilic - hydrophobic
- H-bonds
- covalent (disulphide bridge)
- ionic inter.
- electrostatic inter.
How are quaternary protein structures formed?
By side chain interactions of SUBUNITS:
- hydrophilic - hydrophobic
- H-bonds
- covalent (disulphide bridge)
- ionic inter.
What are the structures of quarternary proteins? What are their characteristics?
- Globular
- Fibrous
- Molecular machines (ATP synthase)
What is the function of protein post-translational modifications (PTMs)?
PMTs are covalent processings that change the properties of a protein - makes them functional
What are heteroproteins?
Proteins which have non am. a. components (prosthetic groups) ex: nucleotides / redox active groups
Explain the structure of a nucleotide?
- Phosphate (at 5C)
- Nitrogenous base (at 1C)
- Ribose (2 OH) / deoxyribose (1 OH) sugar