Enzymes are usually found intracellulary , where they catalyze the biochemical reactions. But in some situation we usually find enzymes in the plasma , and depending on their presence we can diagnose some diseases.
G6PD. American Africans face haemolysis when given primaquine because they had x-linked G6PD deficiency. More severe G6PD deficiency grease middle East 20% and highest 60% in Kurdistan.
Red cell acid phosphate. B type is most frequent 60 to 80%. C type list the point. Europeans have 4 and 9% c-type while a type is 35 to 8%.
6pgd. C-type 3% in Europe but bhutaan 20% and South Africa 15%
ADA. 2 type 5% in Europe. 10% in Greece. 0 to 3 percent in Africa, Japan and eskimos.
PGM. Pgm1 76% England. High levels in Africa and American natives. Rare frequency of 6 and 7 type 1% in China.
I will give some examples:
Liver enzymes test: is a laboratory test , which reflects the damage of liver tissue ,due to a trauma , or following viral infection and cause the presence of liver enzymes in the peripheral blood.
Cardiac enzymes test: we diagnose cardiac damage in myocardial infarction for example by seeking enzymes , such as creatine phosphokinase ( CPK) in the peripheral blood.
So enzymes could be found in blood in low energy situation , stress , chronic disease and others .
Depending on changes in some enzymes level we can diagnose some genetic diseases too.
Even our life style could be detected by enzymes` level in blood , for example eating fast food increases digestion and causes increase in the presence of some digestive enzymes in blood. Other example is the stressful life as we mentioned.
As a conclusion: We may find enzymes in blood , not only inside the cells.