Which of the following is NOT a characteristic of enzymes involved in metabolic pathways?

Enzymes are catalysts that facilitate biochemical reactions in metabolic pathways without being consumed in the process. This means that, after they have catalyzed a reaction, they are available to catalyze subsequent reactions. This is a fundamental characteristic of enzymes, as their role is to lower the activation energy of reactions and increase reaction rates while remaining unchanged themselves.

All the other characteristics listed are indeed true for many enzymes. For instance, many enzymes are influenced by allosteric factors which can enhance or inhibit their activity based on the binding of molecules at sites other than their active sites. Additionally, enzymatic regulation often involves phosphorylation, altering the enzyme's activity, and many enzymes require cofactors such as metal ions or vitamins to function effectively in biochemical reactions. However, the characteristic that enzymes are consumed in the reaction contradicts their fundamental catalytic role, thus making it the correct choice for what does not describe the behavior of enzymes in metabolic pathways.