Protein Structure and Function Flashcards
Protein function is affected by what
Conformations (shape of protein)
Protein structure can be defined at what 4 levels?
-Primary: sequence of amino acids
-Secondary: formation of a coil or sheet
-Tertiary: all coils/sheets together
-Quaternary: interaction of one or more polypeptides to form a functional protein
Amino acids in a polypeptide are connected by what
Peptide bonds
How many amino acids are used to form polypeptides
20
Amino acids within a polypeptide can form noncovalent interactions that cause the polypeptide to do what?
The polypeptide folds
The interactions of amino acids with each other leads to a what level of protein structure
The 2 degree structure
What is secondary structure determined by
Energetic considerations
In a secondary structure free energy is minimized so it is ________
Energetically favorable
Noncovalent interactions can be broken, causing the structure to unfold/ denature including what
-chemicals
-heat
-pH
-Others
In the tertiary structure, an individual polypeptide chain can have multiple regions of what structure
Secondary structure
tertiary structure is the full 3D conformation of the polypeptide including
-helices
-sheets
-loops
-and other folds
All polypeptides will have
1 degree, 2 degree, and 3 degree structure
Some 3 degree structures are functional ________
By themselves
What can 3 degree polypeptide structures do before a functional unit (protein) occurs
interact with other 3 degree polypeptide structures
The interaction of two or more 3 degree polypeptides structures is what
4 degree structure
Quaternary structure is a complex of two or more __________
Polypeptide chains
Does it matter if the polypeptides interacting with one another are the same or different?
No they can be either the same or different
Is protein structure related to function
yes
All proteins bind to what
other molecules
What is a binding site?
where a ligand binds a protein
Are the interactions at protein binding sites covalent or noncovalent
non covalent and specific
binding the ligand changes what
The protein conformation
One the ligand is binded and the protein conformation occurs, what happens
Activation or inactivation of a protein
What are enzymes
Proteins that catalyze chemical reactions
Do enzymes make reactions occur faster?
Yes, 1,000,000
Enzymes hold substrates in ways that allows chemical reactions to occur more easily that does what
Reduces activation energy
Different mechanisms for reducing activation energy depends on what
The enzyme
What are 5 ways that protein activity is controlled
-feedback inhibition
-multiple binding sites
-phosphorylation
-GTP-binding
-ATP hydrolysis
Anabolic pathways produce what for the cell
organic compounds
What are protein kinases
enzymes that add phosphates to other proteins
What are protein phosphatases
Removes phosphates from other proteins
What kind of enzymes have more than one binding site and are active or inactive based on what is bound
allosteric enzymes
ATP binding and ATP hydrolysis causes what type of change in a protein
Conformational change
Motor proteins are involved in what
muscle contractions and transport of materials in cells
GTP is what
Nucleotide triphosphate
When the GTP is hydrolyzed what happens to the protein
the protein is inactivated
Protein is reactivated when
GTP binds again
Phosphorylation may do what to the protein
activate or inactivate
