Microcomputer interface for computer-controlled enzyme kinetic studies with the monolayer technique.
A microcomputer interface for computer-assisted monolayer experiments was developed, tested, and used for analysis of the enzymatic hydrolysis by pancreatic phospholipases A2 (EC 3.1.1.4) of 1,2-didodecanoyl-sn-glycero-3-sulfate monitored under constant surface pressure. The interface described multiplexes two different analog signals onto one set of 12 data input lines to the computer. One signal is obtained from an electromicrobalance which measures surface pressure of a monomolecular substrate layer in a two-compartment trough. The second signal comes from a 10-turns precision potentiometer which measures the position of a surface barrier. Both signals together determine a velocity value which is output via four data lines to a DC motor that drives the barrier. Software developed specifically to drive the interface, to store data, and to keep pressure constant is described.