Carbohydrates and PTM Flashcards
Define what a post-translational modification is.
A chemical reaction that occurs after translation that alters the function and structure of a protein.
Describe proteolysis of insulin.
Insulin undergoes proteolysis to become active.
The polypeptide chain is cleaved to produce the active form of insulin,
Describe ubiquitination.
Ubiquitination is a process by which a protein is marked for degradation. It is a process that requires ATP.
What terminus does ubiquitin bind to?
Ubiquitin binds to the C-terminus of a protein.
Describe the process of phosphorylation.
Phosphorylation occurs when PO42- bonds to the -OH group of the following amino acids: Serine, Threonine & Tyrosine.
What enzymes are involved in phosphorylation?
Kinases catalyse the addition of phosphates; Phosphates catalyse the removal of phosphate.
Describe acetlyation.
Acetylation regulates gene expression, using te enzymes KAT (lysine) or HAT (histone) acetyl transferases.
Describe methylation.
When a H+ on a histone is masked by a CH3.
What type of modifications can the H3 tail undergo?
S-nitrosylation: attachment of NO to thiol group.
Lipidation: addition of a lipid side chain.
How do humans store glucose?
Glucose is stored as glycogen.
What is glucose used for in plants?
Glucose is used to build cellulose which is used to strengthen the cell walls in plants - it is a rigid structure.
Where is chitin found?
Chitin can be found in the shells of crustaceans or in the walls of fungi.
Define an enantiomer.
An enantiomer is an exact mirror image of a molecule.
Define an epimer.
An epimer is a molecule that only shows a mirror image at 1 carbon.
Define an anomer.
An anomer is a molecule that does not show any mirror imaging.
What is glycolysation?
The process of adding a glycan (complex carb) to a protein.
What enzymes are used in glycolistion?
GHs (gylcoside hydrolysases) and GTs (glycosyl transferases)
What is the role of the glycoside hydrolayses?
GHs catalyse the hydrolysis of glycosidic bonds.
Describe N-glycan synthesis.
N-glycan synthesis starts co-translationally, with the addition of Glc3Man9to a structure.
I finishes post-translationally with the modification of the glycan the ER and golgi.
Describe O-glycan synthesis.
Happens post-translationally where the glycan is linked to the -OH side chain.
Takes place in the golgi.
