Proteins Flashcards
(21 cards)
what are the different classes of amino acids? (6)
- aliphatic
- aromatic
- sulphur containing
- basic (NH2 group)
- acidic (COOH)
- uncharged polar
give an example of an aliphatic amino acid?
glycine, alanine, valine
give an example of an aromatic amino acid?
phenylalanine
give an example of sulphur containing amino acids?
cysteine
give an example of a basic amino acid?
lysine
give an example of an acidic amino acid?
aspartate
give an example of an uncharged polar amino acid?
serine
what is the primary structure of a protein?
the sequence of amino acids in a polypeptide chain
what is the secondary structure?
the spatial arrangement of amino acid residues that are near each other in the linear sequence
give two types of secondary structure and the position of bonds?
ALPHA HELIX
- H bonds between every 4th N-H and C=O
BETA PLEATED SHEET
- H bonds between amide groups of linear chains
what is the tertiary structure?
the spatial arangement of amino acid residues that are far apart in a linear sequence
what bonds are present in tertiary structure? (5)
- ionic
- van der Waals
- hydrogen
- disulphide
- hydrophobic interactions
what are hydrophobic interactions?
intra-polypeptide interactions which occur in an environment within proteins, in which water is excluded
what are disulphide bridges?
strong covalent bonds between two cysteine residues
what is the quarternary structure?
the spatial arrangement of induvidual polypeptide chains in a multi-subunit protein
what causes protein denaturation? (6)
- acids
- heat
- solvents
- cross linking reagents
- chaotropic agents
- disulphidebond reducers
what do peptidases do?
cleavage of peptide bonds
what do endopeptidases do?
cleave internal peptide bonds
what do exopeptidases do?
cleave off one amino acid at a time
what do carboxypeptidases do?
cleave at -COOH terminal
what do aminopeptidases do?
cleave at -NH2 terminal
