creatine kinase and MIN

Question 1

reaction involving creatine kinase

Answer 1

creatine phosphate – creatine + ATP

catalysed by creatine kinase using ADP and H+

Question 2

where is creatine kinase

Answer 2

all cells
high in muscles and brain
following death of muscle/brain = CK in circulation

Question 3

isoenzymes of CK

Answer 3

3 in man
2 monomers coded for by different genes
2 subunits M and B
MM MB BB
MB only in myocardium 
in myocardium MB = 15%, MM rest 
isoenzymes separated bt electrophoresis on cellulose acetate strips 
MM move fastest to -ve

Question 4

what happens to cellular contents when cells die

Answer 4

they leave the cell and appear in serum

levels of CK and lactate dehydrogenase in serum can be used as markers for MI

Question 5

what is creatine phosphate

Answer 5

energy store

Question 6

how can you detect CK

Answer 6

coupled assay
creatine phosphate + ADP - creatine + ATP (in presence CK)
D-glucose + ATP - ADP + G6P (hexokinase)
G6P +NADP+ - 6-PG + NADPH + H+ (G6P dehydrogenase)
NADPH detected by UV abs

Question 7

CK monomers

Answer 7

same molecular weight 
different pl 
diff size 
diff 3d shape - more or less soluble 
R gps around edge diff 
associate with each other in cytoplasm

Question 8

using the dimers to detect MI

Answer 8

cardiac only muscle that produces B and M
only place with BM
levels of BM are directly proportional to amount of cell death
each myocyte same vol and so release quantum of CK into ECF and serum

Question 9

how do you experimentally differentiate the isoforms

Answer 9

electrophoresis or column chromatography - slow and rely on expert
spectrophotometry - results vary depending on analytical technique, age, sex, race and gender
immunological - specific Ab that detects BM
test not used alone
show time course and severity rather than that it actually happened

Question 10

time course of CK

Answer 10

short serum half life
should be tested in 24hrs
detect in 3-4hrs
higher for 3-4days

Question 11

other markers for diagnosis of MI

Answer 11

serum glutamate oxaloacetate
lactate dehydrogenase - not cardiac specific
cardiac troponin
myoglobin

Question 12

cardiac troponin

Answer 12

calcium switch in muscle 
cardiac troponin I and troponin T are tissue specific 
specific marker for MI 
appear after 3-4hrs 
stay for 10 days - long half life

Question 13

why would CK be in the blood

Answer 13

tissue damage
dystrophy
MI
small amount normally from skeletal muscle

Question 14

myocardial membrane fluidity

Answer 14

temperature - working faster

Question 15

MI

Answer 15

coronary artery blocked by cholesterol/plaques eg Ca/age degeneration - atherosclerosis
no O2 = no ATP
substances cant be kept inside cell - no AT
creatine kinase leave down conc grad - passive

Question 16

purpose of CK

Answer 16

transportation of phosphate
phosphorylate creatine = phosphocreatine
use ATP

Question 17

re-infarction

Answer 17

thrombin long half life so cant detect re-infarction

creatine can

Question 18

myoglobin

Answer 18

present after 1/2 hour

not cardiac specific

Question 19

how do you detect re-infarction

Answer 19

symptoms
ECG
echocardiogram
radiography

Question 20

atherosclerosis

Answer 20

unhealthy cholesterol 
high Bp
smoking 
diabetes
obesity 
lack of physical activity 
FH