Flashcards
Structural Features of Proteins
Cards in this deck (19)
- 1Give the general formula of amino acids.- R(CH2)NH2COOH
- 2What determines the properties of amino acids?- size, polarity and hydrogen bonding properties of the variable group
- 3What type of isomerism do amino acids show?- stereoisomerism
- 4What are the different types of AA side chains?- aliphatic non-polar = hydrophobic core
- uncharged polar = electronegative oxygen, sulfur... flexible
- charged polar = surface of soluble proteins
- aromatic = mostly non-polar - 5Describe peptide bond formation.- condensation reaction of 2 AAs
- water released
- uses ATP and GTP - 6What are the characteristics of the peptide bond?- partial double bond character
- prevents free rotation around the C-N axis
- some combinations lead to collision or repulsion
- some states more stable than others - 7What is steric hindrance? How can it be shown?- restricts combinations bond positions
- allowed values shown in Ramachandran Plot - 8How are regular structures formed?- same Y and P values for a series of residues
- e.g right-handed helix, beta sheets... - 9Describe the structure of a right-handed helix.- rod-like
- stabilised by h-bonds between residues
- side chains point out
- h-bonds parallel to helix axis
- occur in many soluble proteins
- good for spanning lipid bilayers - 10Describe the structure of parallel and antiparallel beta sheets.- stabilised by h-bonds between adjacent strands
- alternate side chains point in opposite directions
- strand reversal achieved with the beta-turn - 11What is the tertiary structure of a protein?- folds via a series of intermediate conformations with increasing stability
- some orientations are more favourable and stable - 12What factors favour protein folding?- hydrophobic effect = driving force
- non-covalent interactions (ion pairing, h-bonding, VDW forces) - 13What factors favour the unfolded state?- loss of favourable interactions with the solvent when folded
- lower entropy of folded state
- unfavourable VDW interactions - 14Why are proteins easily denatured?- small free energy change
- 15Describe the structure of globular proteins. Give examples.- interior = hydrophobic, few polar side chains, polar groups stabilised by ion pairing, h-bonding
- exterior = hydrophilic, few non-polar side chains
- e.g. myoglobin, lysozymes - 16How is conformational flexibility achieved?- stability determined by many weak interactions
- atoms can move - 17Why is conformational flexibility important?- induced fit
- allosteric effects - 18What are other structural features of proteins?- metal ions
- prosthetic groups/cofactors
- covalent modifications - 19What covalent modifications occur in proteins?- glycosylation
- phosphorylation
- acetylation
- oxidation and reduction
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- Prelims Cells Flashcards on Structural Features of Proteins, created by Kirstin Latimer on 06/01/2016.
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- Kirstin Latimer
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