Susan Elaine Cain, Age 61182 W Marchmont Ln, Reno, NV 89511

4778755, Oct 18, 1988

Aug 8, 1983

6/520921

Yuh-Geng Tsay - San Jose CA
Susan M. Cain - Palo Alto CA

Minnesota Mining and Manufacturing Company - St. Paul MN

C12Q 154
C12Q 134
C12Q 142
C12Q 132
C12Q 100
C12N 999
G01N 33535

435 14

In the determination of the quantity of enzyme present as a result of an immunoassay procedure, the enzyme containing component is combined with a substrate which in the presence of the enzyme yields a photometrically detectable enzymatic reaction product and a non-interfering, enzymatically inhibiting second product. The enzymatic reaction is inhibited by the addition of an inhibiting quantity of the same compound as the second product after the enzymatic reaction has continued for a time sufficient to produce photometrically detectable first products in concentrations which are a function of the quantity of enzyme present. The enzyme reaction is inhibited before the enzymatic reacton has proceeded to the point where the quantity of photometrically detectable first compound is primarily a function of the amount of substrate. This method yields a more stable test medium than methods using other enzyme inhibitors.