protein and hemoglobin part 2 Flashcards
what do hemoglobin and myglobin have in common
8 alpha helices labeled A-H
Mb is similar to what subunit
the Beta
what does the Y02 curve for myoblin and hemoglobin
myoglobin = hyperbola= no cooperativity
Heme= sigmoidal = cooperativity
binding of one substrate molecule to the active site of one subinit locks…
all subunits in active conformation
what is allostery
other site
binding at one site affects what
binding at others
wht does allosterism require
protein wth more than one subinit
what does S curve indicate
cooperativity = allosterism
what is homotropic allosteric interaction
effector and ligand are regulated by the effector are same molecule (eg. O2 and Hb)
what is heterotropic allosteric interaction
effector and liganrd are different molecules
what is an activator
shifts the equilibrium toward R state= stabilizes R state= positive allosteric interaction
what is an inhibitor=
= shifts the equlibrium toward T state= negative allosteric interaction
what does R state mean
relaxed and it has high affinity
what does T state mean
tense- low affinity
does Mb have T and R states
no
what has low affinity in Hb
BPG. H+ and CO2
what has high or relaxed affinity
O2 bc its a homotropic effector
what is the bohn effect
increased temperature = release of o2 from Hb
- increase CO2, decreasing pH or increasing temp causes the release of O2 from HB decreasing affinity for O2
bohr effect
high temp =
high temp = low Hb affinity for
where on T state do Bohr protons bind
N terminal anino gps are responsible for 20-30%
H bonds and ion pairs are present in which state
T state
His 146B does what
accounts for about 40% of the bohn effect
what does the Tto R transition change
- pka of these groups ( lowering pka ) causing them to release coordinated H
can a surrounding protein structure change PKA
yes
H+ (bohr protons ) are releasd when
Hb binds to O2
