Describe the induced fit hypothesis for mode enzyme action. Pepsinogen, a proteinase enzyme of stomach is an exoenzyme or an endoenzyme?How sulfa drugs helpin inhibition of bacterial growth?

Induced fit hypothesis for mode enzyme action is a modification of the lock and key model on enzyme action.

According to this, enzymes are flexible structures and the active site is continuously reshaped by enzyme- substrate  interactions. This means that enzymes does not simply bind to a rigid active site and the amino acid side-chains of the active site mold into the precise positions to enable the enzyme to perform its function. 

In some cases the substrate molecule changes shape of the active site of enzyme slightly as it attaches to it. The active site continues to change until the substrate is completely bound. 

Pepsinogen is an inactive enzyme but can be considered exoenzyme as it acts outside the cell that produces it. All digestive enzymes are exoenzymes.

Sulfa drugs inhibit the folic acid synthesis in the bacterial cell and thus kill them.