What is a non-substrate?

Answer 1

a substrate that is not porous. IE has no pores. But more importantly it is impervious to water or air. In a material this would mean that an adhesive would need to either melt/weld or create a bond between it and the substrate. A water based glue for example would want to penetrate the surface of a substrate to create a surface it can bond to. A non-porous substrate would not allow this and so the bond, if an, would be weak.

Answer 2

A non-substrate is a molecule that acts as an inhibitor or activator of an enzyme but is not the molecule upon which the enzyme acts. Non-substrates can bind to the enzyme at a different site from the active site, altering enzyme activity. Examples include allosteric regulators and competitive inhibitors.