Week 2- Creatine Kinase Flashcards
What is creatine kinase?
An enzyme that converts creatine phosphate to creatine whilst phosphorylating a molecule of ADP to produce ATP
How many types of creatine kinase are there? Name them
2 types: M and B
How many isoenzymes of creatine kinase are there? Name them and state where each is found
There are 3:
MM- found in skeletal muscle and heart
MB- found in myocardium
BB- found in the brain
When is creatine kinase detected in the blood?
When cells die, as it is able to leak out of the membrane
How do myocardial cells become leaky?
Due to hypoxia (a lack of O2)
This is because a lack of oxygen prevents ion transporters pumping ions out of cells so the build up of ions swells the cell, weakening the membrane
How do we determine CK activity?
The ATP produced by creatine kinase activity converts glucose to glucose 6 phosphate and ADP, this reacts with NADH and glucose 6 phosphodehydrogenase to form NADPH. Measuring NADPH levels therefore correlates to CK activity and elevated levels can indicate myocardial infarction
How are isoenzymes separated via electrophoresis?
All 3 have different isoelectronic points (points where the charge equals 0), so when they undergo electrophoresis they move towards the negative end. MM moves the furthest/closest to the negative side as it has the lowest pH, then MB, then BB
How are heart attacks diagnosed?
An antibody that binds to CK BB is added to blood, therefore the activity corresponding to CK BB can be found and this can indicate CK MM and CK MB levels too. Elevated CK MB can correspond to diagnosis of myocardial infarction
NOTE: cardiac cells are regular so will release the same amount of CK MB each, therefore the level of CK MB is a very good indicator to the extent of the infarction
What are some good characteristics of biomarkers?
They stay detectable for a specific amount of time, they are easily and quickly released and detected
