Mcim 326 L9 regulatory mechanisms (inc)
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- T=Absolute Temperature
The 5 Regulatory mechanisms (speac)
-which regulate enzyme activity and which regulate enzyme concentration
- Substrate level
- Covalent modification
- Protein interactions
How can substrate levels be used for regulation?
- -IN A METABOLIC PATHWAY CHANGES IN SUBSTRATE CONCENTRATION [A] AFFECT THE PATHWAY AND CAN BE VERY RAPID(MICROSECONDS).
1) SUBSTRATE CAN BE DIVERTED INTO ANOTHER PATHWAY A --> E
2)TRANSPORT OF A INTO OR OUT OF THE CELL CHANGES [A].
3)OTHER REACTIONS CAN PRODUCE SUBSTRATE A: F --> A G -->A
What is the underlying concept?
- [S] AFFECTS REACTION RATES
- as concentration increases so do reaction rates (V:velocity)
V VS. [S] graph is what shape?
What is KM
- -MICHAELIS MENTON CONSTANT
- -USUALLY A MEASURE OF TIGHTNESS OF BINDING OFS TO THE ENZYME.
KM (LOW) =
HIGH ACTIVITY AT LOW [S] AND VISA VERSA
When is Km = [S]?
Examples of allosteric regulation
how is KM effected?
- -first reaction in isoleucine pathway
- - allosterically inhibited by isoleucine which is and end product of the pathway
-Isoluecine increases Km
of enzyme for Threonine (the substrate)
Example of Allosteric Regulation
Aspartate Transcarbamoylase (ATCase)
- -FIRST REACTION IN THE PYRIMIDINE NUCLEIC ACIDPATHWAY
- -BOTH END PRODUCTS ARE INHIBITORS. WHY?-ATP ACTIVATES:WHY?
T (TAUT) STATE OF ENZYME
WITHOUT SUBSTRATES OR ACTIVATOR
R (RELAXED) STATE OF ENZYME
WITH SUBSTRATES AND/OR WITH ACTIVATOR – PROTEIN HAS CHANGED SHAPE. BINDS SUBSTRATE MORE EASILY
Example of Covalent Modification
-GLUTAMINE SYNTHETASE (GS) IS REGULATED BY COVALENT ATTACHMENT OF AMP(ADENYLYLATION) IN E. COLI.
GS-AMP IS ___ ACTIVE
WHAT DOES COVALENT MODIFICATION ALLOW?
LARGER, MOREPERMANENT REGULATORYEFFECTS TO OCCUR.
WHAT IS THE ENZYME WHICH ADENYLYLATES GS?
Example of regulation by Protein interactions
ADENYLYL TRANSFERASE (ATase)
what protein interacts?
THE ENZYME WHICH ADENYLYLATES GS, IS REGULATED BY BINDING OF A PROTEIN CALLED PII
PII is permanently bound and is regulated by covalent modification
PII IS COVALENTLY REGULATED BY ____
- (ATTACHMENT OF UMP).
PIIA CAUSES ATase TO :
- ADENYLYLATE GS
- -A FOR ADENYLYLATING
PIID-UMP CAUSES ATase TO
UMP is added to PII by:
Histidine Protein kinase is an example of what type of modification?
what system is it from?
- PTS transport system
ATCase CATALYTIC PROTEIN SUBUNITS(S)
regulated by what?
example of what type of regulation?
REGULATED BY REGULATORY SUBUNITS(R)
ATP, CTP, UTP -> bind to R subunit which regulates S subunit
Protein interactions can involve what three of the other mechanisms?
- Allosteric regulation
- covalent modification
- Enzyme levels
The 5 Regulatory mechanism differ in what 3 important ways?
How do the 3 correlate to each other?
As size and permanence increase speed drops
order the 5 Regulatory mechanism according to speed
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