Allosteric control

allosteric, reversible covalent, multiple, proteolytic, enzyme

what are the 5 ways to regulate enzyme activity?

• _____ control

• _________ _______modification

• _______ forms of enzymes

• _________ activation

• controlling the amount of ______ present

allosteric proteins

proteins that can adopt two or more different conformations

allosteric

Most rate-determining enzymes in metabolic pathways are ______

2, ligand, shift

Allosteric Proteins:

• have _____or more distinct binding sites (allosteric modulator)

• _______ binding at one of the sites causes a _____from one conformation to another

ACTase

What is an example of an allosteric enzyme?

transferase

ACTase is classified as a _____ ( one of the 6 types of enzymes)

sigmoidal

ATCase displays ______ kinetics

N-carbamoylaspartate

ATCase catalyzes the formation of ______from carbamoyl phosphate and aspartate.

CTP

N-carbamoylaspartate is used for the synthesis of ______

committed step

forming N-carbamoylaspartate is the ______ in a metabolic pathway

ATCase

______ catalyzes the committed step in the metabolic pathway for CTP biosynthesis.

dec

INC the concentration of CTP leads to a _____ in the activity of ATCase activity

neg

the activity of ATCase is _____regulated by CTP.

off

Thus, the end product (CTP) serves as a signal to switch _____ ATCase

committed

In feedback regulation, the step that is regulated is almost always the ______ step

T, R

What are the 2 conformational states of ATCase?

• ____ state and ____ state

T state

What is the ATCase conformational state?

• the active site of the enzyme is NOT in optimal shape;

• largely inactive

• LOW affinity

• stabilized by inhibitors (CTP)

no, inactive, low, inhibitors

T state

• Is active site of the enzyme in optimal shape?

• This state is largely _______

• ____ affinity

• Stabilized by _____

R state

What is the ATCase conformational state?

• the active site of the enzyme IS in optimal shape;

• largely active

• HIGH affinity

• stabilized by substrates

yes, active, high, substrates

R state

• Is active site of the enzyme in optimal shape?

• This state is largely _______

• ____ affinity

• Stabilized by _____

R

the bi-substrate PALA binds to the ____ state of ACTase

PALA

________ is used by biochemist to stabilize ATCase in its active state

sigmoidal

allosteric enzymes display _____ kinetics

R

INC substrate concentration for ACTase shifts more and more enzymes into ____ state

Homotropic

_______ effects:

• the effects of substrates on allosteric enzymes

Heterotrophic

_______ effects:

• the effects of non-substrates on allosteric enzymes

kinase

Phosphorylation is catalyzed by protein ______

phosphate

Dephosphorylation is catalyzed by protein ______

2 neg

Phosphorylation adds ____ ______ charges to the surface of the modified protein

chymotrypsin, trypsin, elastase

what are 3 Ser proteases?

ser

chymotrypsin, trypsin, elastase are ____ proteases

ser, cys, aspartyl, metalloproteases

what are the 4 major types of proteases?

• _____ proteases

• ______ proteases

• _______ proteases

• ________

asp - his - ser

SER proteases

• use SER as a nucleophile

• Typically contains a catalytic triad ______

cys-his

CYS proteases

• use CYS as a nucleophile

• Typically contains a catalytic dyad ______

asp, water

Aspartyl proteases:

• Using a pair of _____ residues to activate ____as a nucleophile

zinc, water

Metalloproteases:

• uses ____ ion to activate ____ as a nucleophile

bulky nonpolar

chymotrypsin prefers:

• _____ ______ side chains

lys, arg

trypsin prefers:

• ____ and ____ side chains

small nonpolar

Elastase prefers:

• _____ ______ side chains

peptide

Chymotrypsinogen is activated by specific cleavage of a single ____ bond

pancreas, zymogen, chymotrypsinogen

Chymotrypsin is synthesized in the _____as a ______( inactive substance) called ______

inactive

Chymotrypsinogen must be _____ until it gets to the digestive tract

trypsin

The first step in activating chymotrypsinogen is its digestion by _______, which then activates it

enteropeptidase

Trypsinogen is converted to active trypsin by __________.

• Trypsin then activates all of the pancreatic zymogens