The study by Arthur Karmen, Felix Wróblewski, and John S. Ladue investigated transaminase activity in human blood. Transaminases catalyze the reversible transfer of amino groups between amino acids and alpha-keto acids. Two main transaminases were studied: glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase. These enzymes were found in human serum and blood cells, with activity varying in diseased states. The method involved measuring glutamate production through paper chromatography. Serum and blood samples were incubated with substrates, and glutamate levels were determined. The results showed that transaminase activity in serum was directly proportional to incubation time and serum volume. The activity was stable under various storage conditions, except for boiling, which destroyed it. In normal humans, glutamic-oxalacetic transaminase activity ranged from 0.41 to 1.36 micromoles per ml per hour, while glutamic-pyruvic transaminase activity ranged from 0.21 to 1.01 micromoles per ml per hour. In whole blood hemolysates, glutamic-oxalacetic transaminase activity was ten times higher than in serum, and its activity was approximately 2.7 times that of glutamic-pyruvic transaminase. Transaminase activity was found to increase in certain disease states, such as lymphomatous disease, rhabdomyosarcoma, acute leukemia, acute hepatitis, and arteriosclerotic heart disease. In patients with acute myocardial infarction, transaminase activity increased, suggesting that cardiac muscle damage may release the enzyme into the bloodstream. The study demonstrated that transaminase activity in human serum and blood cells is enzymatic and has similar properties to those in animal tissues. The results suggest that transaminase activity in serum may originate from blood cells or other sources. The study also showed that transaminase activity is stable under various conditions, making it a useful marker for disease. The findings support the use of transaminase activity as a diagnostic tool in clinical settings.The study by Arthur Karmen, Felix Wróblewski, and John S. Ladue investigated transaminase activity in human blood. Transaminases catalyze the reversible transfer of amino groups between amino acids and alpha-keto acids. Two main transaminases were studied: glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase. These enzymes were found in human serum and blood cells, with activity varying in diseased states. The method involved measuring glutamate production through paper chromatography. Serum and blood samples were incubated with substrates, and glutamate levels were determined. The results showed that transaminase activity in serum was directly proportional to incubation time and serum volume. The activity was stable under various storage conditions, except for boiling, which destroyed it. In normal humans, glutamic-oxalacetic transaminase activity ranged from 0.41 to 1.36 micromoles per ml per hour, while glutamic-pyruvic transaminase activity ranged from 0.21 to 1.01 micromoles per ml per hour. In whole blood hemolysates, glutamic-oxalacetic transaminase activity was ten times higher than in serum, and its activity was approximately 2.7 times that of glutamic-pyruvic transaminase. Transaminase activity was found to increase in certain disease states, such as lymphomatous disease, rhabdomyosarcoma, acute leukemia, acute hepatitis, and arteriosclerotic heart disease. In patients with acute myocardial infarction, transaminase activity increased, suggesting that cardiac muscle damage may release the enzyme into the bloodstream. The study demonstrated that transaminase activity in human serum and blood cells is enzymatic and has similar properties to those in animal tissues. The results suggest that transaminase activity in serum may originate from blood cells or other sources. The study also showed that transaminase activity is stable under various conditions, making it a useful marker for disease. The findings support the use of transaminase activity as a diagnostic tool in clinical settings.