PROTEINS, STRUCTURE, FUNCTION

?
Structure of amino acids
Enantiomers= nonsuperimposable mirror images
1 of 14
primary structure
involves the linking of l-amino acids by peptide bonds between -COOH and NH2 groups
2 of 14
Primary structure and peptide bonds
sequence of AA from n-terminus to c-terminus joined by peptide bonds between -COOH and -NH2
3 of 14
Secondary structures
A-helix B-sheets and loops/turns =formed by bending or coiling of amino acid chain which involves rotation around N-C (phi), (alpha) and (PSI) bonds
4 of 14
The alpha helix
typically about 12-15 residues long i.e 3-4 turns and 1.8 nm. h0bonding between the c=o of one AA and N-H of another. four residues in the chain. they are amphipathic
5 of 14
Beta Sheets
typically about 6-10 residues per strand 2-10 strands/per sheet. strands within sheets are represented by flat arrows. anti-parallele (oposite dirrections) and parallel (same direction).
6 of 14
Loops and turns
turns=short. loops and coils = longer (>6 residues) and more disordered. Beta turn= the c=o group of residue 1 of the tetrapeptide forms a H-bond with N-H of residue 4 and causes a hairpin turn.
7 of 14
Tertiary structure of proteins definition
3-D folding of the secondary structural elements to give the final, native conformation
8 of 14
Tertiary structure
Helices and Beta sheets run across the protein. Turns and loops are usually at the edges. The core is densely packed and water is excluded. The core has some flexibility but the edges are much looser. Structure dtermined by sequences
9 of 14
Polarity of the cytosolic protein and Membrane protein
Cytosolic protein- are polar on the surface and hydrophobic inside. Membrane proteins- Hydrophobic on the surfaces that are in contact with the membrane.
10 of 14
Principles contributing to the determination of the tertiary structure
Hydrophobic side chains - prefer to be buried inside proteins. polar side chains are hydrophillic and prefer to be on the surface in contact with water. (unless a membrane protein in which case external enviroment is hydrophobic so oposite is true).
11 of 14
Motifs
also called super-secondary elements. combinations of a few elements of secondary structure. e.g - helix-loop-helix and zinc fingers.
12 of 14
Domains
larger structures, more like small proteins. discrete functions or activites. e.g- dehydrogenase domain
13 of 14
Importance of motifs and domains
important in providing help in folding and stability to the protein. They have been important in the evolution of proteins. alpha tubulin is a globular protein that forms fibrous supra-molecular structures.
14 of 14

Other cards in this set

Card 2

Front

involves the linking of l-amino acids by peptide bonds between -COOH and NH2 groups

Back

primary structure

Card 3

Front

sequence of AA from n-terminus to c-terminus joined by peptide bonds between -COOH and -NH2

Back

Preview of the back of card 3

Card 4

Front

A-helix B-sheets and loops/turns =formed by bending or coiling of amino acid chain which involves rotation around N-C (phi), (alpha) and (PSI) bonds

Back

Preview of the back of card 4

Card 5

Front

typically about 12-15 residues long i.e 3-4 turns and 1.8 nm. h0bonding between the c=o of one AA and N-H of another. four residues in the chain. they are amphipathic

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all PROTEINS resources »