C4 Protein Flashcards
Catalyzes formation or breakage of covalent bonds
Enzyme
Binds to DNA to switch genes on or off
Gene regulatory protein
Generates movement in cells and tissues
Motor protein
Used by cells to detect signals and transmit them to the cell’s response machinery
Receptor protein
Each succesive amino acid adds to the ? end of a peptide
carboxyl
Primary structure of protein?
amino acid sequence
Bond between amino acids in a protein
peptide
alpha-helix and beta-sheets are (1,2,3*) structures of Proteins
2*
Denatured protein in water using urea. Then observed conformation reformed upon removal of urea.
Anfrinson
Anfrinson determined..
amino acid sequence determines structure
The CAP protein has one large, and one small ?
domain
Any segment of a polypeptide chain that can fold independently into a compact, stable structure
domain
The secondary structure of proteins is generally a result of ?
H-bonding
The tertiary structure of proteins is a result of ?
side chain interactions
proteins with similar structure but different function
protein families
proteins made of four subunits
tetramer
dimer of the same two polypeptides
homodimer
hemoglobin is a dimer of ?
heterodimers
Simple, elongated, three-dimensinal protein
fibrous
myosin has this structure
coiled coil
Proteins bind their ? with great specificity
ligands
What is meant by high affinity binding?
The ligand with a higher affinity will be present in the binding region more readily than one with a low affinity
Enzyme binds to ? of substrate
transition state
hydrolases
catalyze hydrolytic cleavage
nucleases
hydrolysis of nucleic acids (cleaves phosphodiester bonds)
proteases
hydrolysis of proteins (breakdown peptide bonds)
kinase
phosphate transfer
phosphatase
hydrolytic removal of phosphate
ATPases
hydrolyze ATP
Three ways in which enzymes lower activation energy
1) binds and orients two substrates to encourage reaction 2) rearrange electrons within substrate 3) strains substrate into transition state
factors affecting enzyme activity
temp, ph, substrate concentration, inhibitors/activators
[ES] x k_cat
V
michaelis-menton equation. V=?
V_max x ( [S] / ( [S] + K_m ) )
Achieved when enzyme is saturated with substrate
V_max
Reaction velocity when the substrate concentration is at the K_m
V_max / 2
K_m =
(k_off + k_cat) / (k_on)
Michaelis-menten plot is a plot of ? vs ?
concentration vs velocity
lineweaver-burke plot is a plot of ? vs ?
1/concentration vs 1/velocity
the x intercept of a lineweaver burke plot is equal to
-1/K_m
the y intercept of a lineweaver burke plot is equal to
1/V_max
slope of a lineweaver burke plot is equal to
K_m / V_max
inhibitors that bind so tightly to an enzyme that they “kill” it
irreversible
bind to active site or compete with the normal substrate
competitive inhibitors
changes the conformation site of the enzyme and interferes with its ability to catalyze
noncompetitive inhibitor
a competitive inhibitor reduces ?
k_on
a noncompetitive inhibitor reduces ?
k_cat
a ? inhibitor gives a new V_max
noncompetitive
On a L-B plot, a ? inhibitor has a different x-intercept
competitive
On a L-B plot, a ? inhibitor has a different y-intercept
noncompetitive
A ? inhibitor requires more substrate to get to its original V_max
competitive
Enzymes that undergo a conformational change between active and inactive forms
allosteric
What effect do allosteric effectors have on allosteric enzymes
change equiibrium
Are synthesized as inactive precursors that require modification
zymogens
What usually modifies zymogens
proteolytic cleavage
A common mechanism for turning a protein on or off
de/phosphorylation
Act as molecular timers
GTP-binding proteins
How do GTP-binding proteins act as molecular timers
after hydrolysis of GTP, a slow step occurs where GDP dissociates before another GTP can attach
EF-Tu is an example of this kind of protein
GTP-binding
Function of EF-Tu
binds tRNA to ribosome
hydrolysis of EF-Tu (attaches/releases) it to/from tRNA
releases
A non-nucleic acid infectious disease
PrP
if it takes one second for a molecule to move 1um, how long does it take to travel 10um?
100 seconds
how does an alpha helix form
NH of every peptide bond is H-bonded to the C=O of peptide bond located 4 AA’s away
CAP small domain binds to ?
DNA
CAP large domain binds to ?
cyclic AMP
Serine protease family (3)
elastase, chymotrypsin, trypsin
Proteins secreted by the cell to form gel-like matrix
Fibrous
Three fibrous proteins
keratin, collagen, elastin
collagen structure
triple helix
elastin structure
covalently crosslinked
keratin structure
coiled coil
target of antibody called ?
antigen
hexokinase add phosphate to ? but ignores ?
D-glucose, L-glucose
model enzyme
lysozyme
lysozyme function
severs polysaccharide chains of cell walls of bacteria
rhodopsin
non protein component of a rhodopsin protein that detects light
Three methods of enzyme control
production of enzyme. compartmentalization of enzyme. enzyme itself (inhibitors, temp, ph)
Amount of enzymes phosphorylated at any one time
1/3
set of covalent modifications a protein contains at any moment
regulatory protein code
in vitro literally mean?
in glass
in vivo literally means
in the living
How is protein AA sequence determined
breaking polypeptide with selective proteases
