biochemistry -glycolysis

what does glycolosis result in

pyruvate formation

what are the 2 fates of pyruvate metabolisim

lactate and ACetyl CoA

what pathway results in lactate

anaerobic

what pathway results in ACa

aerobic

what converts pyruvate to lactate

lactate dehydrogenase

what does actate dehydrogenase require and where does it get it from

requires NADH

-supplied from glycolosis

what is the fate of glucose in yeast

pyruvate then either :

Ethanol of Acetyl coA

explain how ethanol is produces

pyruvate is converteed to acetaldehyde but pyruvate decarboxylase

aceta;dehyde is converted to ethanol via alcohol dehydrogenase

How many steps are in glycolysis?

10

what are the 2 phases of glycolosis

investment and pay off phase

step one in the investment phase

-what converted to what

-what enzyme used

-anything lost

glucose converted to Glucose-6-phosphate

enzyme is hexokinase

ATP converted toADP

step TWO in the investment phase

-what converted to what

-what enzyme used

-anything lost

glucose 6 phosphate is converted ti fructose -6- phosphate

enzyme :phosphoglucose isomerase

step three in the investment phase

-what converted to what

-what enzyme used

-anything lost

fructose-6-phosphate is converted to fructose1-6 biphosphate

enzyme used :phosphofructokinase

Atp is used in the reaction

step four in the investment phase

-what converted to what

-what enzyme used

-anything lost

fuctose1-6 biphosphate is converted to either dihydroxyacetone phosphate or Glyceraldehyde-3-phosphate

enzyme used :aldolase

note

dihydroxyacetone phosphate and Glyceraldehyde-3-phosphate can be interchanged via the enzyme triose phosphate isomerase

what do we have at the end of the investment phase

2x glyceraldehyde 3-phosphate molecules

step one in the pay-off phase

-what converted to what

-what enzyme used

-anything lost

g;yceraldegyde3-phospahte is converted to 1,3 bisphosphoglycerate

enzyme used :Glyceraldehyde 3 phosphate dehydrogenase

NAD+ reduced to NADH

phosphate is added

step two in the pay-off phase

-what converted to what

-what enzyme used

-anything lost

1,3 bisphosphoglycerate converted to 3-phosphoglycerate

enzyme used

phosphoglycerate kinase

ADP converted to ATP

step 3 in the pay-off phase

-what converted to what

-what enzyme used

-anything lost

3-phosphoglycerate CONVERTED TO 2-PHOSPHOGLYCERATE

enzyme used

-phosphoglycerate mutase

step 4 in the pay-off phase

-what converted to what

-what enzyme used

-anything lost

2-PHOSPHOGLYCERATE converted to phosphoenolpyruvate

enzyme used

enolase

step 5 in the pay-off phase

-what converted to what

-what enzyme used

-anything lost

phosphoenolpyruvate converted to pyruvate

enzyme used

pyruvate kinase

ATP generated

what is the first key enzyne in the control of glycolytic flux

hexokinase

what is the size and shape of hexokinase

100kdA HOMODIMER

how many isoforms of hexokinase and what is the main isoform

4 isofoms

hexokinase II is the main isoform

what are all hexokinases inhibited by

All of the isoforms apart from4 are inhibited by their products(glucose -6-phosphate) in a negative feedback inhibition

why does the hexokinase 4 not experience negative feedback

Isoform 4 does not experience the inhibition and is therefore important in the liver and the brain as you always need this reaction to occur

explain how a high fat diet in a mouse contributes to obesitey

Give mice high fat diet

Increased expresseion of the glucokinase

Transmits a signal via the vagus nerve

The brown fat switches of in the body and brown fat thermogensis is decreased

what promoted glusocse consumption in rates

an increase in arcuate glucokinase

explain the increase in arcuate glucokinase increase

-fasting causises the following

increased glucokinase

decrease in the potassium ATP channel

increase in the calcium ions

increase in Neuropeptide Y release

increase in glucose consumption

what is the second key enzyme in the control of the glycolytic flux

phosphofructokinase

what is the phosphofructokinase enzyme size and structure

360kDa tetramer

how many isoforms of the phosphofructokinase enzyme

3

what are the 3 isoforms of the phosphofructokinase (PFK)enzyme

muscle

liver

platelet

what does a mutation in PFK-M enzyme lead to

tauris diseases

-muscle weakness and myopathy

what inhibits phosphofructoinase

ligh levels of ATP allosterically inhibit the enzyme

how does ATP inhibit phosphofructokinase

ATP binds to a specific regulatory site that is distinct from the catalytic site. The binding of ATP lowers the enzyme's affinity for fructose 6-phosphate.

what activates phosphofructokinase

F-2 and 6BP

fructose 2, 6 biphosphate

what is the enzyme that generates an allosteric effect of phosphofructokinase

phosphofructokinase 2 and fructose biphosphatatse 2

what is the structure of the phosphofructokinase 2 / fructose biphosphatatse 2 enzyme

110-220 kDa

-homodimer of 2 enzymes

-a kinase at the N-terminus and a phosphatase domain at the c terminus

how many isoforms of the phosphofructokinase 2 / fructose biphosphatatse 2 enzyme (PFK

4

liver muscle and fetal-PFKB1

cardiac-PFKB2

placental inducable brain PFKB3

testse -PFKB4

what regulates the phosphofructokinase 2 / fructose biphosphatatse 2 enzyme

glucagon and insulin

are the phosphofructokinase 2 / fructose biphosphatatse 2 enzyme the same thing

No, PFK-2 and FBPase-2 are not the same, but they are two enzymatic activities of the same bifunctional protein, known as 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB).

what does phosphofructokinase 2 (PKK-2) do

Adds a phosphate to fructose-6-phosphate (F6P), converting it into fructose-2,6-bisphosphate (F2,6BP).

what si the result of fructose-2,6-bisphosphate (F2,6BP). formation

Effect: Increases F2,6BP, which activates PFK-1 and enhances glycolysis.

what doesFructose-2,6-bisphosphatase (FBPase-2) do

Removes a phosphate from F2,6BP, converting it back to F6P.

what is a result of the activity of Fructose-2,6-bisphosphatase (FBPase-2)

Decreases F2,6BP, reducing PFK-1 activity and favoring gluconeogenesis.

explain the regulation of PFK-2 and FBPase-2 whith glucagon

Glucagon binds to the glucagon receptor when blood glucose levels are low.

This activates adenylyl cyclase, which increases cyclic AMP (cAMP) levels.

cAMP activates protein kinase A (PKA), which phosphorylates the PFK-2/FBPase-2 enzyme, activating FBPase-2 and inactivating PFK-2.

FBPase-2 reduces fructose-2,6-bisphosphate (F2,6BP) levels by converting it back to fructose-6-phosphate (F6P).

Since F2,6BP is an activator of PFK-1 (a key enzyme in glycolysis), its reduction inhibits glycolysis and promotes gluconeogenesis instead.

explain the regulation of PFK-2 and FBPase-2 whithinsulin

Insulin binds to the insulin receptor when blood glucose levels are high.

This activates a protein phosphatase, which dephosphorylates the PFK-2/FBPase-2 enzyme, activating PFK-2 and inactivating FBPase-2.

PFK-2 increases fructose-2,6-bisphosphate (F2,6BP) levels, which strongly activates PFK-1, stimulating glycolysis.

What is the 3rd key enzyme in the control of the glycoltic flux

pyruvate kinase

what is the structre and size of pyruvate kinase

228kDa tetramer

how many isoforms of pyruvate kinase

4

liver

erythrocyte

muscle

fetal

what regualtes pyruvate kinase

glucagon and insulin

explain the regulation of pyruvate kinase by glucagon

Glucagon binds to the glucagon receptor (when blood glucose is low).

This activates adenylyl cyclase, which increases cyclic AMP (cAMP) levels.

cAMP activates protein kinase A (PKA), which phosphorylates pyruvate kinase, inhibiting it.

Inhibited pyruvate kinase means phosphoenolpyruvate (PEP) is not converted to pyruvate, reducing glycolysis.

Instead, PEP can be used for gluconeogenesis, producing glucose.

Glycolysis is turned OFF.

explain the regulation of pyruvate kinase by insulin

Insulin binds to the insulin receptor (when blood glucose is high).

This activates pyruvate kinase phosphatase, which removes the phosphate group from pyruvate kinase, activating it.

Active pyruvate kinase converts PEP to pyruvate, producing ATP and promoting glycolysis.

Fructose-1,6-bisphosphate (F-1,6-BP) acts as an activator, ensuring the reaction proceeds efficiently.

Glycolysis is turned ON.