Week 11 Flashcards
T/F:
DNA is chemically homogenous, proteins are chemically heterogenous
True
What is the proteome?
The proteins expressed by a genome at any one time
T/F:
Cells respond to the environment by changing their genome not proteome
False
Otherway round
What is a PTM?
Post translational modification
Additions or subtractions to translated proteins that can alter the chemical structure of a protein and therefore modify its function
How many different PTMs are possible at different sites in the protein?
6
Therefore 720 possible combinations of gene products
What are the two major classes of PTMs?
Enzymatic vs non-enzymatic
Give two examples of non-enzymatic PTMs
Oxidation of proteins in the presence of reactive oxygen species
Deamidation
Give some examples of enzymes involved in enzymatic PTMs
Kinases/phosphotases
Acetyltransferases/Acetylases
Methyltransferases/methylases
O-GlcNAc tranferase/O-GlcNAcase
Does a kinase of phophatase remove a phosphate group?
Kinase= adds a phosphate Phosphotase= removes phosphate group
Which type of enzymatic PTM acts as a ‘switch’
Kinase/phosphatase
T/F:
Phosphorylation is rapid, coordinated and easily reversible
True
Which two enzymes are involved in glucose production in terms of phosphorylation?
Glycogen synthase and Glycogen phosphorylase
T/F:
Phosphorylation inhibits glycogen phosphorylase and activates glycogen synthase
False
Other way round
In what ways can PTMs alter protein structure and interactions?
Hydophobicity interactions
Charge-charge interactions
Hydrogen-bond interactions
What happens to protein function when PTMs alter charge-based interactions?
Inhbitis ability of the enzyme to bind to its structure and vice versa
T/F:
ROS are found in normal healthy cells
True
List some anti-ROS defence molecules
Superoxide dismutase (SOD)
Catalase
Peroxiredoxins
Glutathione peroxidase
What is the role of glutathione?
Short tri-peptide that mops up free oxygen via oxidised cysteine
Which organelle is a major source of ROS?
Mitochondria
Which ROS is massively increased when electron transport in mitochondria is interefered with?
Superoxide
What does SOD convert to?
H2O2 and O2
What does H2O2 react with?
Reacts with reduced metal ions to create OH- (really dangerous)
Which two enzymes remove H2O2?
Catalse and GSH peroxidase
