Q. For the enzymatic reaction what is the effect of a substance with the same spatial conformation like an enzymatic substrate? How is this kind of substance known?

Substances that to "simulate" substrates can bind to the activation center of enzymes thus blocking the true substrates to paralyzing the enzymatic reaction and bind to these enzymes. Such "fake substrates" are termed as enzyme inhibitors.

The binding of enzyme inhibitors to enzymes can be irreversible or reversible.

Many medical drugs, for example, some antibiotics, antineoplastics, antivirals, antihypertensives and even sildenafil (trade name Viagra), are enzyme inhibitors that block enzyme activity.