Protein Structure Flashcards
Name the hydrophobic a.a.
Alanine, valine, phenylalanine, tryptophan, leucine, isoleucine, methionine, proline
What is special about aromatic R groups?
They absorb UV light at 280 nm
What is special about methionine
Contains sulfur (thioether)
Is prolines side chain aromatic or aliphatic?
Aliphatic with cyclic structure
What is primary structure, what bonds
Sequence of amino acids in a polypeptide, joined by covalent (peptide) bonds
Where do peptide bonds absorb UV light
230 nm
What is secondary structure, what is the main bond
Local folding of the backbone into regular or irregular structure, joined by H bonds (C=O and N-H), ion pairs (salt bridges)
Are irregular loops on the inside or the outside of proteins? Why?
Outside because there is no H-bonding (they are more polar than regular structures)
What is tertiary structure
Arrangement of 2o structures in relation to one another, globular or fibrous, can have prosthetic group
What kinds of forces stabilize 3o structure
Hydrophobic effect (driving force), H-bonding (fine-tune), disulfide bonds, ion pairs (salt bridges)
What are disulfide bonds/bridges
Covalent bonds between close cysteines, only under oxidizing conditions (not in cytosol)
What is a domain?
Polypeptide segment folded into single structural unit with hydrophobic core (>200 residues = 2< domains)
What is a motif
Short region of a polypeptide with recognizable 3D shape (grouping of 2o structure) e.g. Greek Key, zinc finger
What is a prosthetic group
Nonprotein component permanently in protein providing structure (zinc fingers) or reactive groups (heme)
What is quaternary structure
Proteins composed of more than one polypeptide chain (each chain = subunit)
