Biochem Essay Exam 3- Phosphoglycerate kinase

What is the abbreviation for phosphoglycerate kinase?

PGK

What is PGK?

An enzyme found in glycolysis pathway

What does PGK do in glycolysis?

Catalyzes step 7

Where does glycolysis occur?

In the cystol

What does glycolysis do?

Convert glucose to energy

What is special about PGK and where it is in glycolysis?

It is the first ATP producing step

What is the reaction? 1,3-biphosphoglycerate + ADP—>

3-phosphoglycerate + ATP

What type of molecule is PGK?

A kinase

What does PGK do as a kinase?

Transfers a phosphate group

What are some roles of PGK?

• Phosphoryl transfer

• Transferase enzyme

• Substrate level phosphorylation

PGK transfers a ___ from a ____intermediate directly onto ADP to make ___.

Phosphate, sugar, ATP

What is the substrate?

1,3-biphosphoglycerate

What are the products?

3-phosphoglycerate and ATP

What is a common cofactor?

Mg+2

What does the cofactor do in the reaction?

The metal ion stabilizes ATp and phosphate groups

Are vitamin derived coenzymes required?

No

How does the catalysis mechanism work?

Through induced fit

Step 1 of catalysis mechanism

Both substrates bind

Step 2 of catalysis mechanism

PGK closes around them

Step 3 of catalysis mechanism

The phosphate group is transferred

Step 4 of catalysis mechanism

ATP and 3-phosphoglycerate are released

Is there a covalent enzyme intermediate?

No (2)

Is there a direct phosphate transfer?

Yes

Is this a reversible or irreversible reaction?

Reversible

Where is energy conserved from in the catalysis mechanism?

The high energy phosphate bond

Is PGK a major regulatory enzyme in glycolysis?

Nope!

What does activity depend on?

• Substrate availability

• Product concentration

• Cellular energy demand

What happens to PGK’s activity level when glycolysis speeds up?

It speeds up too

Can it also participate in glucogenesis?

Yes, since it’s reversible

Phosphoglycerate kinase deficiency is ____

Rare and inherited, likely through X-linked recessive genes

Symptoms of PGK deficiency?

• Anemia

• Muscle weakness

• Exercise intolerance

• Muscle cramps

• Neurological symptoms

Why does PGK deficency cause those symptoms?

Since RBCs rely entirely on glycolysis for ATP because they lack mitochondria. Without PGK, there is less ATP, making more fragile red blood cells, which can cause hemolysis.

Nutritional factors:

• General healthy diet (not malnourished)

• Adequate carbohydrate consumption (glucose)

• Magnesium rich roods since MG+2 is cofactor (Spinach, nuts, beans, whole grains)