chapter 02 enzymes iii regulation i · mishkat ihsan key sat 10 july lecture 3: isoenzymes...
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Chapter 02
Enzymes
III
Regulation I
Mishkat Ihsan
Mishkat Ihsan
Key
Day Date Month Lecture # : tittle#
Key word material / explaination
Question answer
"
You can use
this section to test
yourself bycovering
the rightside p
and retain information
usingthis side ( left
side ) only"
# → number.
are you will findthe meaning of
each shortcut that is used above"
Mishkat Ihsan
Key
Sat 10 July lecture 3 : Mechanisms of Regulation
LD Expression of Isoenzymes .
↳ Regulation of Enzymatic Activity .inhibitors
↳ conformational changes of enzymes and EnzymaticRxns.
↳ Allostery .
↳ Modulators ( inhibitors / activators . . . )
↳ Reversible covalent modification .
4> Irreversible covalent modification .
↳ Regulation of envy me amount .
↳ Location (compartmentalization + completingof enzymes
↳ Non - specific Regulation .
Rxnls) → reaction is) .
Mishkat Ihsan
Key
Sat 10 July lecture 3 : Isoenzymes ( isozymes) .
What are isozymes ? they are enzymes that can act on the same substrates) producingthe same products) .
⇒ So, they catalyse the same rxn .
Isozymes are v. similarDifferences b/w ① They are produced by different genes← only varry slightly .
isozymes ?② They are present in different tissues . c- can be in the same tissue .
③ Regulated differently . Gene Gene Gene Gene
A B C D
how ?
④ They have different Catalytic Activity.how ?
Isozyme Isozyme Isozyme Isozyme
① ;) r /①r A ☐ c ☐
s s←
r
isozyme # I L isozyme#2 isozyme# 3
Catalyses A -30 catalyses 0-1 can catalyseMuscle stomach Embryo cancer cells
⑦ efficiently than 4efficiently than both rxns0 → A b-so efficiently .
0 activating ☐ inhibiting neither
Aerobic Us . AnaerobicMetabolism Glucose
NAD-1 ADP
← to rxns in Glycolysis .
Why change pyruvate to produce NA15→ to sustain gtycotitil result -DATP + NADH
to lactate? pathway (glycolysis) NADH < > ATP Re- carrier
while producing enough ATD V
PyruvateEnzyme if ✗ 02 if V02to keep the system goingLactate Enzyme
Dehydrogenase pyruvate
NADH dehydrogenase
Lactate TNAD' >
Acetyl C0A Aerobic MetabolismAnaerobic metabolism
C02-1HN^
CITRIC ACIDCYCLE
/ CREBS
ATP ← Oxidative NADH
phosphorylation←FADH <
>
ATP
rxn → reaction.
# → number.
In → high / increase.
b/w → between .
Mishkat Ihsan
Key
Sat 10 July lecture 3 : Lactate Dehydrogenases ( LDH )
It is not a single Enzyme it is in reality 5 different enzymes .
All LDH enzymes are tetrameric enzymes .
↳ composed of 4 polypeptides .
LDH - I
LDH enzyme can be made of :I or 2 protein subunits : ③ they all catalyse the same rxn :
Different combinations ofLDH -2
① H ( produced in high quantities in heart) .→ Hand it causes LDH -3
② M ( produced in high quantities in skeletal muscles + liver) . 5 LDH : LDH -4 oxidizedLDH -5
NAD"
NADH + H'
OHo
21-1+-125 Oo
4 Differences b/w ISOZYMES ? ↳ different primary structure due to CH} CH C Lactate -dehydrogenase CH} C C
o-
o-
4> different kinetic Lactate 21-1++25 Pyruvate
properties . NAD' NADH -11-1-1
↳ different isoelectric
point. reduced
④ different Regulation
D taffinity to lactateisozymes are highly homologues
u.g.m.w.m.n.ae#.....µ , ,, ,,,,,a,..
☐ isoemymeslfesen-in-ea.edu
① they are produced by LDHI myocardialNADT NA0H-1HT
net charge H4 Myocardiuminfraction
¥nD LDH > 1
different genes 14in heart) Lactate☐
☒ PyruvateI ' r n
oxidized
> they all <☐H2,
It} MI RBC
-
LDHB subunit③ they are
→
can catalyzecatalyze the 9At heart'
present in g reduction but pretense ②$A same r×n §.
oxidan.cn . Different
µp,
different ¥ LDH } § Hzmz Lungs - CatalyticS tissues
isozymes s ActivityE.Nucleus subunit S (Affinity)MLmuscle)
liver LDHY HIM } Kidney-
tonet charge- 6
NADH -11-1-1 NADT-(DH5
R×"LDH 7M5 Skeletal muscle Skeletal muscle ~D Lactate'
☐ Pyruvate① in muscles + +
+ liver ) liver liverdisease reduced
☐LDH 5 favors pyruvate reduction
rxn → reaction.
# → number.
4 affinity to pyruvate
4 → high / increase. ⑦
b/w → between .① affinity ( tkµ ) to S
→ low / decrease . → they prefer to catalyseS → Substrate S
.
Mishkat Ihsan
Key
4 LDH ILDH 5 ( heart TH)
( muscles + liver)Blood """
ereaq.gg,
5
3 NADT NADH + It'
NADH + It' NADT 7
7 Lactate☐
☒ Pyruvate6 oxidized
^"""" "° " ""
reduced Glucose "All It,
"
"All My" NAD-1 ADP
Why is the locationthat's why z
of LDH imp . ? ,EÉ tatiinity to lactate
Muscles can function anaerobically o
NAD" < > ATPLDHI favors lactate oxidation
-
Vbut the heart tissue Cann't .±
Pyruvate <Enzyme if ✗ Oz if ✓ 02
7
EnzymeLactateÉÉDehydrogenase
pyruvatethat's why
)L NADH dehydrogenase (LDH 5 favors pyruvate reduction Lactate TNAD" >
4 affinity to pyruvateAcetyl C0A Aerobic Metabolism 8
2 Anaerobic metabolism7 II C02-1HU producing a lot
"
anaerobic ATP in muscles finish producing some ^CITRIC ACID of energy
energy that CYCIE
quickly so another source forsustains / CREBS
ATP is needed Oxidativethe musclesATP ←
phosphorylation←^^""
FADHT10 TTTP
9r
rxn → reaction.
# → number.
In → high / increase.
b/w → between .
I → low / decrease .
Mishkat Ihsan
Key
Sat 10 July lecture 3 : Regulation of LDH
☐ I KM for pyruvate + is not inhibitedLDH 5 My & by pyruvate
( muscles + liver) 4 affinity for pyruvate4) always 4
active pyruvate reduction
even at 4 levels of pyruvatewhy ?
to ensure that pyruvate is always funneled to anaerobic metabolism.
→ ⑥ Km for lactate + 4 Km for pyruvateLDH 1 Iv( heart TH ) 4 affinity for lactate + is inhibited by 9 pyruvate .
4 Ilactate oxidation . if heart muscle produces 4 pyruvate
①Rxn Stops①
allowing lactate to be present inother tissues .
rxn → reaction.
In → high / increase.
b/w → between .
I → low / decrease