If {HEAD ~ the quantitatively determinable substance} contained in {TAIL ~ the cells} of the reagent is enzyme , this reagent further contains a substrate which specifically interacts with the enzyme  
If { HEAD ~ the quantitatively determinable substance } contained in { TAIL ~ the cells } of the reagent is enzyme , this reagent further contains a substrate which specifically interacts with the enzyme
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH