Final answer:
Substituting tyrosine for cysteine in the active site of an enzyme can have various effects, potentially altering enzyme-substrate interactions and enzyme activity.
Step-by-step explanation:
If tyrosine is substituted for cysteine in the active site, it can have various effects on the enzyme's function. Tyrosine is a different amino acid than cysteine, and its side chain is larger and more polar. This substitution can alter the structure and chemical properties of the active site, potentially affecting enzyme-substrate interactions and the catalytic activity of the enzyme. Depending on the specific enzyme and reaction involved, this substitution could lead to decreased enzyme activity, loss of specificity for the original substrate, or possibly even complete loss of enzyme function.