Creatine Kinase

Question 1

What reaction does the enzyme creatine kinase catalyse?

Answer 1

Creatine phosphate -> creatine + ATP

Its reversible
Delta G = -31 KJ/mol (ATP) and -43.1KJ/mol (CP)

Question 2

What is creatine kinase?

Answer 2

Its present in all cells but is found din high concentration in muscle and brain cells

Question 3

What happens following the death of cells?

Answer 3

CK is released into circulation

Question 4

What forms does CK exist in?

Answer 4

Exists as three dimeric isoenzymes:
MM
MB
BB
MB is only found in myocardium

Question 5

How can you separate the three dimeric isoenzymes?

Answer 5

By electrophoresis

MM moves furthest towards negative electrode

Question 6

What causes leaky plasma membranes?

Answer 6

Atherosclerosis (blockage of coronary artery) leads to hypoxia
This leads to less ATP production meaning powered ionic pumps don’t work properly
This leads to a leaky membrane causing small cell content and water imbalance
The imbalance increases and the cell bursts
Enzymes like CK are released

Question 7

How to measure CK activity?

Answer 7

Couples assay- tae a sample, centrifuge to separate blood components- enzymes found in plasma

Question 8

What are the locations of CK release?

Answer 8

Brain only expresses B form- BB form only generated
MM only made in skeletal muscle cells
MB only made in myocardium (heart muscle)

Question 9

How can we diagnose myocardial damage?

Answer 9

CK activity
LDH activity
SGOT- serum glutamate oxaloacetate transaminase
Cardiac troponin