Answer:
their shape, which relates to the lock-and-key model
Explanation:
Enzymes are biological catalysts that are proteinous in nature. Their proteinous nature implies that they are made of amino acids, which forms a three-dimensional shape that accounts for their functionality and specificity. This means that enzymes are substrate-specific because of their 3D shape.
The three-dimensional shape of an enzyme determines the kind of substrate it will bind to. Enzymes, generally, catalyze reactions by binding to a substrate at their active site. This binding follows a lock and key pattern or model. In a nutshell, the primary source of specificity of enzymes is attributed to their SHAPE, which relates to the lock-and-key model.
