New system of continuous monitoring of enzyme activities and determination of some substrates.

The proposed system of continuous monitoring of enzyme activities is based primarily on the electrochemical behaviour of thiol compounds, and the experimental equipment is extremely simple. The determination of cholinesterase (EC 3.1.1.8) activity is described. The normal values obtained for men (73.9, s +/- 10.3 microkat/l) and for women (71.1, s +/- 10.2 microkat/l), lie within the usual range of analogous photometric methods. Systems for determination of the activities of alkaline phosphatase (EC 3.1.3.1) and adenosylhomocysteinase (EC 3.3.1.1) are described. The activity of aspartate aminotransferase (EC 2.6.1.1) is determined by a combination of enzyme reactions, in which CoA is released from acetyl-CoA. Analogous procedures are discussed for determinations of alanine aminotransferase (EC 2.6.1.2), lactate dehydrogenase (EC 1.1.1.27), lipase (EC 3.1.1.2), and phospholipase A2 (EC 3.1.1.4) activities, and for determination of substrates, e.g., acetate and carnitine. Possible determinations of an additional 199 enzyme activities and of some of substrates are suggested. By determining electrochemically active groups other than thiols this method becomes almost universally applicable.