peroxidase

This term is a technical biochemical designation used almost exclusively in scientific, medical, and academic registers. It describes a specific class of enzymes, and its usage is typically restricted to laboratory reports, peer-reviewed journals, and textbooks on biochemistry or plant physiology.

Because it refers to a specific chemical entity, it is treated as an uncountable noun when referring to the substance or the general enzymatic activity. While it can be pluralized in specific contexts to refer to different types of peroxidases (e.g., comparing various peroxidase isoforms), in most general scientific descriptions of the enzyme's function, it remains uncountable.