All enzymes are :

Enzymes are biological catalysts that significantly increase the rate of chemical reactions within living organisms [t1, t2]. Chemically, all enzymes are proteins [t5]. They are composed of amino acid chains folded into unique three-dimensional structures, which create specific active sites for substrate binding [t5, t7]. While some enzymes require non-protein components called cofactors or coenzymes (such as vitamins or metal ions) to function, the primary catalytic structure remains proteinaceous [t1, t8]. Cellular DNA serves as the information source for synthesizing these proteins [c4]. Unlike carbohydrates, which primarily serve as energy sources, or lipids, which function as fuel storage and structural components of membranes, enzymes perform dynamic catalytic roles [t5, t10]. Although a small class of RNA molecules called ribozymes also possesses catalytic activity, in the context of general biological classification, enzymes are defined by their protein nature [t6].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 8: Heredity > 8.2.3 How do these Traits get Expressed? > p. 131
2. [2] https://www.sciencedirect.com/topics/immunology-and-microbiology/metabolism