Topic 4- enzymes regulation Flashcards by Isabel Morgan

Serpins

> Competitive irreversible inhibitors> protease

>AS > comformational change

How well did you know this?

Not at all

Perfectly

List 3 Serine proteases

> Trypsin
Chromotrypisin
Elastase

How well did you know this?

Not at all

Perfectly

What is Zymogen

> inactivated single polypeptide

How well did you know this?

Not at all

Perfectly

Describe activation of Chromotrypsin

> Zymogen

>Trypsin activates——> chymotrypsin (2 poly)——–> Alpha chymotrypsin (3 poly)

How well did you know this?

Not at all

Perfectly

Describe trypsin Activation

> Trypsinogen (zymogen)

>Enteropeptidase removes small peptide chains ——-> Trypsin

How well did you know this?

Not at all

Perfectly

What does Antithrombin III do?

> Controls tight binding of thrombin to serine

>swithches off blood clotting sydtem

How well did you know this?

Not at all

Perfectly

Give example of serpins

> Serine Proteases

How well did you know this?

Not at all

Perfectly

what is the blood clotting cascade

> enzyme activation events
Intrinsic/ extrinsic pathways
collects soluble proteins>Fibrin clot formed
amplifies initial sequence

How well did you know this?

Not at all

Perfectly

What initiates blood clotting cascade

> Blood Factors > serine protease

How well did you know this?

Not at all

Perfectly

What happens if there is a deficiency in blood factors ?

> Clotting/ bleeding disorders

How well did you know this?

Not at all

Perfectly

What factors are involved in enzyme control?

> Inhibition
Negative feedback
Phosphorylation
Proteolytic activation

How well did you know this?

Not at all

Perfectly

What is endogenous enzyme Inhibition?

> Serine protease inhibitors
A1-antitrypsin
Pancreatic Trypsin
Antitthrombin III

How well did you know this?

Not at all

Perfectly

A1-antitrypsin

> Prevents protease attacking tissue

How well did you know this?

Not at all

Perfectly

Pancreatic Trypsin

> Regualtes digestive enzyme activity

How well did you know this?

Not at all

Perfectly

What is negative feed back

> Controls balance
Stop signal when enough is made
Amplify signal> when more needs to be made
pathways > linked

How well did you know this?

Not at all

Perfectly

Phosphorylation

> Covalent modification
P from ATP transferred to residue via Protein kinase
P removed from residue via protein phosphatase
P indufe charges> change shape > affect activity

How well did you know this?

Not at all

Perfectly

Proteolyctic action

> Activate zymogen/ pro enzyme
irreversible clevage> amide
bonds

How well did you know this?

Not at all

Perfectly

examples of proteolyctic action (2)

> Pancrease

>Blood clotting sydtem

How well did you know this?

Not at all

Perfectly

What are enzymes?

Biological catalysts
specific
protein

How well did you know this?

Not at all

Perfectly

How do enzymes work?

inc. rate eq reached

lowering AE

How well did you know this?

Not at all

Perfectly

How do enzymes lower the AE

> Catalytic components
Bind and orientate
Binding and stabalises transitional states

How well did you know this?

Not at all

Perfectly

AS properties

> Specific 3D shape
small part of protein
Crucial amino acids

How well did you know this?

Not at all

Perfectly

What is Michaelis constant

> Affinity of enzyme for substrate

How well did you know this?

Not at all

Perfectly

Equation for Michaelis constant

Km = (K2 + K1)/ K3

How well did you know this?

Not at all

Perfectly

What is K1, K2 K3?

K1: Rate ES is formed | K2 + K3: Rate ES is dissociated

which is the rate determining constant

What is the velocity?

Reaction rate | change in product over time

What is IU?

International enzyme units

What does IU measure

Amount of enzyme that will catalyse 1 micromol of substrate / minute under optimal conditions

how many micromoles in a mol

10^6

What is the vMax?

Theoretical max reaction rate

What factors affect rate of reaction

>[Substrate] and [enzyme] >temperature >pH >Inhibitors

How does pH aftect rate

proteins protonates and deprotonates

What are the types of inhibitors

>Reversible - no/ reversible covalent bonds >Irreversible - covalent bonds >Competitive >Non competitive

Describe Competitive inhibitor

> binds to AS >Prevents ES >inc [S]> overcome

Describe Non competitive inhibitor

> Binds to allosteric site> alters shape >EI /EIS >[S] > NO affect

What happens to Km and Vmax with a competitve inhibitor

Vmax same | Km change

What happens to Km and Vmax with a non competitive inhibitor

Vmax change | Km same

competitive examples

``` REVERSIBLE Methotrexate Ibuprofen NON REVERSIBLE Aspirin ```

How do Aspirin and Ibuprofen work?

>Inhibit prostaglandis synthesis | >competitively inhibiting COX-1 COX-2

How does Methotrexate work

> Similar structure to Dihydrofolate> DNA + RNA >Bind to AS >inflammation (low) >cancer (high)

Example of non competitive inhibitor

>Alanine

How does alanine work?

> inhibits Pyruvate kinase >-ve feed back >Pyruvate kinase catalyses pyruvate phosphoenol pyruvate to pyruvate which is converted to to alanine

What do IC50 values measure?

The inhibitor conc that r`educes enzyme activity by 50%

What does a low IC50 mean

> better inhibitor> less moles needed to inhibit

What is an enzyme called with metal in active site?

>Metalloprotein

Roles of metalloproteins

>Redox and oxidation reactions Fe2+/Fe3+ | >Regulate enzyme activity

Name some major minerals in AS

>Mg2+ | >Ca2+

Name some trace elements

``` >Cu2+ >Zn2+ >Mn2+ >Mo2+ Fe 2+/3+ ```

What are Coenzymes?

>Small organic molecules | >Carriers

Examples of Coenzymes

>Coenzyme A> Acyl units >Biotin and Thiamine Pyrophosphate > C02 >NADH / FADH2> carry e-

What do NAD+ act as

Oxidation agent | accepts H+ and e-

How is NAD+ Formed

>Niacin sits on larger molecule becomes Nicotinamide

Pellagra

>Caused by niacin deficiency

What does G6DPH stand for?

>Glucose-6-phosphate dehydrogenase

What is G6DPH needed for?

NADPH production

Explain conversion of Glucose to Glycolysis in terms of an equation

Glucose---->Glucose 6-phosphate-------> 6-phosphoglucono-s-lactone -------->Glycolysis------->engergy or --------->Pentose phosphate pathway

What does the conversion of Glucose 6-phosphate to 6-phosphoglucono require? How does the negative feed back work?

>Conversion of NADP+ to NADPH >G6PDH >Inc. NADP > Inc in enzyme activity

What happens if G6PDH not present

>Primaque haemolytic anaemia and favism

What is Primaqye haemolytic anaemia

> RBC destroyed faster than made

What kind of inherited disease is defective G6PDH

>X recessive

What 2 products does the pentose pathway poroduce?

>Ribose 5- phosphate===> Nucelic Acids | >NADPH====> Reducing power for biosynthesis

How does Glutathione repair damaged membrane? What does it require ? what relies on this process for production of NADP+

>Oxidation and reduction .>Glutathione reductase, NADPH, Glutathione peroxidase >mitochondria

What happens if Glutathione is defective?

>Cannot reduce> Run out of glutathione

What happens if G6DPH is defiecient

>No NADPH production | >Cannot reduce> glutathione runs out

What are malaria patients treated with? what does it do? | Affect of deficient G6DPH

>Primaquine >Stimulates oxidative species> bad for parasites and mem lipids >defective G6DPH mean mem cannot be repaired> RBC deform

What has G6DPH deficiency lead to?

>Resistance to malaria

What pro drug is used in cancer treatmeant?

>6-mercaptopurine 6-MP

How is it activated describe 2 path ways

>3 enzymes metabolise> 6-methyl MP----->Blocks of DNA sythesis----->cell death >TPMT metabolises to 6-methyl MP> nothing happens

What is TPMT

Thiopurine methyl transferase

Describe how you can have deficient TPMT | and how this influences your dosage of 6-mercaptopurine 6-MP

>1 chromosome defected> half amount >both chromosome defected> O amount >Lower dose> Cell lysis pathway more prevalent

Topic 4- enzymes regulation Flashcards

(71 cards)