Enzymes, enzymatic kinetics, and
enzyme inhibition are
topics covered
in undergraduate biochemistry textbooks, having perceptible relevance
to everyday life. The experimental use of enzymes involved in basic
physiologic processes may be of utmost pedagogic interest because
they bring evidence on how a significant number of drugs are used
to control illnesses. Salivary and pancreatic α-amylases are
essential digestive enzymes responsible for the partial hydrolysis
of starch, the primary source of calories in human diet. As the structures
of α-amylase from human pancreas and porcine pancreas are highly
similar, the latter is an enzyme that can be easily used in laboratory
classes at an accessible price. The activity of this enzyme can also
be easily and affordably evaluated by resorting to the substrate 2-chloro-4-nitrophenyl-α-d-maltotrioside (CNPG3). Here, we propose an active-learning
environment activity where students use a physiologically relevant
enzyme (α-amylase) to develop an experimental protocol, explore
their own experimental results, and discriminate between different
kinetic models. For this purpose, students are invited to select the
best experimental protocol (optimizing the activity conditions/concentration
of the enzyme and substrate, pH and temperature parameters), to discriminate
different enzymatic models and determine the kinetic parameters through
both linear transformations of the Michaelis–Menten equations
(Lineweaver–Burk double-reciprocal transformation) and nonlinear
regression using the Solver tool of Microsoft Office Excel.