6: protein function Flashcards
(32 cards)
ubiquitination
adds 75 ama -> degrades unwatned protein
add acetyl group
acetylation
sumoylation
add SUMO, an ubiquin-like modifier
=> repress gene expression
demonstrate the role of kinase and phosphatase
amino acids’ HYDROXYL is phosphorylated w/ help of kinase = an enzyme tht catalyze the transfer or PO4 to that molec
reversts back using phosphatase = catalyzes hydrolysis
___ bind metal ions necessary for activity in enzyme
metalloprotein
adds fatty acids, alter location
myristoylation and farnesylation
glycosylation
affects protein folding solubility and binding to other molec
how does P53 work?
as tumour supressor protein, when stress/UV/radiation, PMT signal to kinase, activate via phosphoryaltion, cell apoptosis & DNA repair
protein and ligand: the general
priteins contains a binding site to which the ligand binds
binding: ionic, hydrophobic
what is myoglobin? heme? histidien?
myoglobin consists of 8 a-helices and 1 heme prosthetic group
is O-binding protein; O is the ligand
Heme: 4 N coordination stabilizes the Fe in the centre
This binds to Histidine: O interacts with Fe; His E7 comes clower to O to stabilize
ligand binding as described by…
Kd
PL <-> P + L Kd = PXL/PL
lower Kd, high affinity tight bonding
Mb + O2 <-> MbO2 as described by
Y02 (fractional sat of myoglobin)= pO2 (partial P) / K + partial P
when Kd = P02
when K = P50
half of the bonding iste is occupied
myoglobin’s partial P is half sat
p05 is 2.9 torr
after that, increase rapidly
Bohr effect:
carbonic acid dissociates into ___ acid and ___
__ binds to ___
in acidic enviro, promotes a bond btw __ & ___ (salt bride) and stable T state
since __ < ___, becomes ___: Hemo release o2 into circulatory system -> lungs
carbon dioxide diffuses in
-> meets H20 and carbonic anhydrase
-> creates carbonic acid
=> in CO2, ___ pH ___ affinity
histidine & B-subunit
pK 6 > pH / deprotonated
O2 binding to Hemo is ____
create
cooperati9ve
S shaped curve
from T to R state
low ot high affinty
deoxy to oxy
a conform change occur: bind at a- & B- glohin and is oxygenated
in T state, HisF8 is proportional to Heme; in R state, becomes clower and stabilize
role of bisphosphoglycerate BPG
stabilize T state; w/o it, Hemo bidns to O2 too tightly can’t realease it in tissue
in high altitudes, RBC creates more BPG
create a less steeep graph
how harmful can Hb variants be?
Hb variatns causing disease
Boston, Milwauke, and Iwate: promotes methomoglobin formation
Yakima: disrupt H bond that stabilize T state
doesnt bind to O2 well
mutation ___ in __ chains -> 2 fewer negative charges
REPLACE w/ ___ creates ___ interactions
Hb aggreates __< becomes ___
Sickle cell
Ê6V / B
valine hydrophobic
form / sickle-shaped
use of OHPro
stabilize 3x helix via H bonds and promtoes conform of 3 a-chains
allow thermal stability at 37c
describe collagefn 3x
made of 3 intertwined poly-Pro type II chains
every 3rd if Gly or kink
Gly’s side chain is amll enough tb the centre
poly-proline type II helix vs a-helix
more extended
no intra-chain __ bonds of ___ & __ IS WIDE ENOUGH
STABILIZED BY s___ ____ of Pro;s side chains
___ residues per rurn
H /amide / O
steric repulsion
3
describe collagen formation:
is synthesized as ——-
polypop catalyzed that 3 strands into __-____ ______
is dumped into extracellular by _______
collagen fibrils aggregate to form collage ___
pro-collagen polypep
pro-collagen molec
pro-peptidase
fibers
___’s chain will itneract with Lys’s NH3_
-> INVOLVED IN CROSS LINKING, CREATE COV BOND
-> stabilize collagen fibrils
allysine
