1l- Amino acid sequence determines protein structure Flashcards
What are proteins?
Polymers of amino acid monomers
What are amino acids linked with to form polypeptides?
Peptide bonds
Amino acids all have the same basic structure differing only in what?
The R group present
What are the ways in which R groups can vary?
- size
- shape
- charge
- hydrogen bonding capacity
- chemical reactivity
What are the four classifications of R groups?
- basic (positively charged)
- acidic (negatively charged)
- polar
- hydrophobic (non-polar)
What does the wide range of functions carried out by proteins result from?
The diversity of R groups
What is the primary structure of a protein?
The sequence in which the amino acids are synthesised into the polypeptide
What results in secondary structure?
Hydrogen bonding along the backbone of the protein strand
What are the three types of secondary structure?
- alpha helices
- parallel or anti-parallel beta sheets
- turns
What does the tertiary structure of the protein involve?
The folding of the polypeptide chain to give a more complex 3D structure
How is tertiary structure stabilised?
By interactions between the R groups
What are the five interactions between the R groups that help stabilise tertiary structure?
- hydrophobic interactions
- ionic bonds
- LDF’s
- hydrogen bonds
- disulfide bridges
What are disulfide bridges?
Covalent bond between R groups containing sulfur
Where does quarternary structure exist and what does it describe?
It exists in proteins with two or more connected polypeptide subunits. It describes the spatial arrangement of the subunits
What is a prosthetic group?
A non-protein unit tightly bound to a protein and are necessary for the proteins function
What is an example of a prosthetic group?
The ability of haemoglobin to bind to oxygen is dependent on the non-protein haem group
What can interactions between R groups be influenced by?
Temperature and pH
What affect can temperature have on the interactions between R groups?
Increasing temperature disrupts the interactions that hold the protein in shape, and the protein begins to unfold, eventually becoming denatured
What affect does pH have on the interactions between R groups?
The charges on acidic and basic R groups are affected by pH. As pH increases or decreases from the optimum, the normal ionic interactions are lost, which gradually changes the conformation of the protein until it becomes denatured
