3D Structure Of Proteins Flashcards
Folding of polypeptide chain is determined by:
Amino acid sequence Molecular structure + properties of its amino acids Molecular environment (solvents + salts)
Amino acids fall into categories defined by …… and …… properties
Structural
Chemical
Properties of amino acids are determined by their structure
Properties of individual amino acids are determined by variable side chain
Charged amino acids may be subdivided into acidic(-ve) and basic (+ve)
Charged amino acids are polar in nature
Carboxyl groups COO- are …… or ….
Charged or acidic
Amine groups NH3^+ are ……. or……..
Charged or basic
2^o amine groups NH + carbonyl group C=O are …….
Polar
Hydroxyl group OH^- are …….
Polar
Hydrocarbon is. ……..
Non-polar hydrophobic
Describe the structure of peptide bond?
Is flat planar structure with rotational freedom within molecule found around alpha carbon
What role does non covalent bonding play in determining folding?
Weak
Determine most of structure
What role of electrostatic attraction in determining folding?
Falls off exponentially as distance increases, affected by electrostatic environment
Typically occurs in aqueous environment
What are Van Der Waals attraction?
Weak forces occur between 2 atoms in non covalent attractions
Determined by their fluctuating change
Attraction at close distance is balanced by repulsion due to proximity that is determined by VDW radius of an atom
VDW forces are induced by proximity of molecules
What are hydrophobic interactions?
H2O is polar molecule
Hydrophobic interactions minimise disruption of H2O network
4th weak force
What are forces determining protein structure?
Electrostatic interaction= attraction of oppositely charged groups such as carboxyl and amine groups of aspartic acid and lysine
Hydrogen bonds
Hydrophobic effect
VDW interaction
What are disulphide bonds?
Covalent bonds
Form between side chains of 2 cysteine molecules
Bonds form in oxidative reaction
SH group from each cysteine cross link
Can form on same (intra-chain) or different (inter-chain) polypeptide chains