This laboratory exercise uses a problem-based approach to exposestudents to some basic concepts relating to proteins and enzymes. One of the mainapplications of enzymes at the industrial level is their use in the detergent market. Thestudents examine a detergent sample to ascertain whether proteolytic enzymes are acomponent and, if so,which colored detergent granules contain them.A4-hour standardexercise is described that can be easily modified to study a number of conditions thataffect enzymatic activity. The students also become familiar with polyacrylamide gelelectrophoresis as it is used to visualize the products of enzyme activity.