Proteins Flashcards
Name an example of a hydrophobic/non-polar amino acid.
Glycine, alanine, valine, leucine, isoleucine, methaoine, proline, phenylalanine, trytophan.
Give an example of a polar, charged amino acid.
Asparte, Lysine, arginine, histidine, glutamate.
Give an example of a polar, uncharged amino acid
Serine, theroine, glutamine, cystine, asparagine.
What happens if the pH of a solution is lower than the pK value of an amino acid?
The amino acid will be protonated.
What happens if the pH of a solution is greater than the pK value of an amino acid?
The protein will be deprotonated.
Define the isoelectric point of a protein.
The pH at which there is no overall charge in a protein
What are the characteristics of a basic protein?
Contain many positively charged, basic amino acids
What are the characteristics of an acidic protein?
Contain many negatively charged, acidic amino acids. pI
What is a conjugated protein?
Contains covalently linked chemical components in addition to amino acids?
What are the four levels of protein structure?
Primary structure, Secondary Structure, Tertiary structure and quaternary structure
What are the key features of an alpha helix?
Part of the secondary structure of a protein, 3.6aa/turn, 0.54nm pitch, right handed helix. Backbone c=o group is hydrogen bonded to a n-h group 4 amino acid residues away.
What are the key features of a B-strand (or extended confirmation)
0.35nm between amino acids, r groups alternate between opposite sides of the chain.
What are the 3 types of B-Strand?
Parallel (strands run in the same direction), antiparallel (strands run in different directions) and mixed (both parallel and anti-parallel parts)
What are the two types of tertiary structure?
Fibrous (long strands or sheets, support, shape, protection) and globular (compact shape, catalysis and regulation)
What two types of globular structures are there?
Domains (with a specific functional role) and motifs (folding patterns containing one or more elements of secondary structure)
Name three of the forces involved in maintaining protein structure?
Three of: covalent (disulphide bonds), hydrophobic effect, van der walls forces, hydrogen bonds, ionic interactions.
How do proteins fold?
All information for folding found in the primary sequence, not a random process, and sometimes chaperones are used to help with the folding of the proteins.
What is an amyloid fibre?
Misfolded, charged form of normally soluble protein. Stabilised by lots of b sheets and hydrophobic interactions.
Define a protein
Proteins are polypeptides made up of amino acids, which are joined covalently to determine the structure of the protein.
What are some of the features of a peptide bond?
Planar, and with partial double bond characteristics so rigid.
