An allosteric enzyme is an enzyme that cannot be inactivated can recognize different stereoisomers of the same substrate can in either an active or an inactive conformation

To analyze the characteristics of an allosteric enzyme, let's break down the provided statements: 1. **Cannot be inactivated**: This statement is not true. Allosteric enzymes can be inactivated, but they do so through different mechanisms compared to non-allosteric enzymes. 2. **Can recognize different stereoisomers of the same substrate**: This statement is also not a defining characteristic of allosteric enzymes. While some enzymes can recognize different stereoisomers, this is not specific to allosteric enzymes. 3. **Can be in either an active or an inactive conformation**: This statement is true. Allosteric enzymes can exist in multiple conformations, typically an active form that binds substrates and an inactive form that does not. Based on this analysis, the correct characteristic of an allosteric enzyme is that it **can be in either an active or an inactive conformation**.