BSI Lecture 3 Protein Function Flashcards
6 Types of Protein Function
- structural
- regulatory
- contractile
- immunological
- transport
- catalytic
Structural
form structural framework
Regulatory
alters cell function (hormones, neurotransmitters, receptors)
Contractile
allows shortening of muscle cells
Immunological
aid responses that protect body against foreign substances and invading pathogens
Transport
carry vital substances throughout body
Catalytic
enzymes that regulate biochemical reactions
Proteins interact with what molecule(s) to carry out their functions?
ligands
True or False? Ligands have to fit perfectly into their binding site.
True
What holds the ligand in place?
Many bonds between the ligand and the side chains of the proteins in binding site.
What types of bonds and attractions hold the ligand into the binding site?
Non-covalent bonds (hydrogen bonds, ionic bonds, hydrophobic interactions, and Van der Waals attraction)
What determines the function of a protein?
Its conformational shape
What determines the types and locations of binding sites
shape
True or False? If the conformational shape of a protein changes, the binding site may change.
true
What 2 things may happen in regards to the ligand and protein if the conformational shape of the protein changes?
- ligand will not bind
2. not enough bonds will be made to hold the ligand in place
Define: Denaturation
The process in which a protein loses its quaternary, tertiary, and secondary structure present in their native state
What causes protein denaturation?
Temperature, pH, Electrolyte concentration
What is disrupted during denaturation?
Nonconvalent bonds maintaining secondary, tertiary, and quaternary structure
Define: Protein Turnover
Balance between protein building and degrading.
True or False? All proteins have a finite lifetime with in the cell.
True
What reasons would cause a protein to degrade?
Normal turnover/renewal, mechanism of cellular control, cellular adaptation, damaged, misfolded
What is the function of the Ubiquitin-proteasome system?
To identify degradation signals on protein to begin the process of degrading a protein
What is the first step in the UPS?
Protein is tagged with ubiquitin
What enzyme recognizes specific degradation signals on proteins and then adds a chain of ubiquitin?
Ubiquitin ligases
What recognizes tag (chain of ubiquitin) and degrades the protein?
Proteasome
What are degraded proteins turned back into?
peptides
What recognizes tag (chain of ubiquitin) and degrades the protein?
20s cylinder and 19s caps
20s cylinder contains ___________
proteases
What is the function of the 19s caps?
Recognizes ubiquitin on the protein as a tag for destruction and unfolds protein and feeds it into the chamber
Enzymes act as a __________, which lowers _________ ________
Catalysts; activation energy
Define Activation Energy
The amount of energy required for a reaction to take place ( to convert the substrate into a transition state)
Catalysts convert substrate into product by _______ or _______ _________ bonds.
Making; breaking; covalent
What do catalyst do?
speed up the reaction rate that would normally be slow
Coenzyme
a small molecule that functions as a transient carrier of a functional group
Cofactor
inorganic ion or molecule that is required for enzyme activity
Why, if a protein denatures, will it lose its function?
It causes the protein to lose its shape, the ligand will no longer bind properly to the protein and can no longer perform its function.
What type of noncovalent bond assist the ligand to get into position?
Hydrophobic interactions.
What matters in the function of the protein?
Size, shape, and chemical properties
Hydrolases
hydrolytic cleavage reaction
Nucleases
break down nucleic acids
Proteases
break down proteins
Synthases
synthesize molecules in an anabolic rxn
Isomerases
rearrange bonds within a single molecule
Polymerases
polymerization rxn
Kinases
add phosphate groups to molecules
Phosphatases
remove phosphate group from molecules
Oxido-reductases
catalyze rxns in which one molecule is oxidized and the other reduced
ATPases
hydrolyze ATP
Ligases
catalyzes condensation rxns in which 2 atoms are joined using ATP or GTP
Dehydrogenases
remove pairs of hydrogen atoms
