Flashcards in C4 Protein Deck (82):
Catalyzes formation or breakage of covalent bonds
Binds to DNA to switch genes on or off
Gene regulatory protein
Generates movement in cells and tissues
Used by cells to detect signals and transmit them to the cell's response machinery
Each succesive amino acid adds to the ? end of a peptide
Primary structure of protein?
amino acid sequence
Bond between amino acids in a protein
alpha-helix and beta-sheets are (1*,2*,3*) structures of Proteins
Denatured protein in water using urea. Then observed conformation reformed upon removal of urea.
amino acid sequence determines structure
The CAP protein has one large, and one small ?
Any segment of a polypeptide chain that can fold independently into a compact, stable structure
The secondary structure of proteins is generally a result of ?
The tertiary structure of proteins is a result of ?
side chain interactions
proteins with similar structure but different function
proteins made of four subunits
dimer of the same two polypeptides
hemoglobin is a dimer of ?
Simple, elongated, three-dimensinal protein
myosin has this structure
Proteins bind their ? with great specificity
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
catalyze hydrolytic cleavage
hydrolysis of nucleic acids (cleaves phosphodiester bonds)
hydrolysis of proteins (breakdown peptide bonds)
hydrolytic removal of phosphate
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
michaelis-menton equation. V=?
V_max x ( [S] / ( [S] + K_m ) )
Achieved when enzyme is saturated with substrate
Reaction velocity when the substrate concentration is at the K_m
V_max / 2
(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
the y intercept of a lineweaver burke plot is equal to
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
bind to active site or compete with the normal substrate
changes the conformation site of the enzyme and interferes with its ability to catalyze
a competitive inhibitor reduces ?
a noncompetitive inhibitor reduces ?
a ? inhibitor gives a new V_max
On a L-B plot, a ? inhibitor has a different x-intercept
On a L-B plot, a ? inhibitor has a different y-intercept
A ? inhibitor requires more substrate to get to its original V_max
Enzymes that undergo a conformational change between active and inactive forms
What effect do allosteric effectors have on allosteric enzymes
Are synthesized as inactive precursors that require modification
What usually modifies zymogens
A common mechanism for turning a protein on or off
Act as molecular timers
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
Function of EF-Tu
binds tRNA to ribosome
hydrolysis of EF-Tu (attaches/releases) it to/from tRNA
A non-nucleic acid infectious disease
if it takes one second for a molecule to move 1um, how long does it take to travel 10um?
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 ?
CAP large domain binds to ?
Serine protease family (3)
elastase, chymotrypsin, trypsin
Proteins secreted by the cell to form gel-like matrix
Three fibrous proteins
keratin, collagen, elastin
target of antibody called ?
hexokinase add phosphate to ? but ignores ?
severs polysaccharide chains of cell walls of bacteria
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
set of covalent modifications a protein contains at any moment
regulatory protein code
in vitro literally mean?
in vivo literally means
in the living