Enzymes (or enzymes) are proteins that act like biological catalysts (biocatalysts). Catalysts speed up chemical reactions. Substrates are molecules on which enzymes can act. The enzyme then converts these substrates into other molecules called products. Enzyme catalysis is required for almost all metabolic processes within the cell to occur at sufficient rates to sustain life. 8.1 Metabolic pathways are dependent on enzymes to catalyze individual processes. Enzymology is the study of enzymes. The pseudoenzyme analysis field recognizes that some enzymes lost their ability to catalyze biological reactions during evolution. This is often evident in their amino acid sequences or unusual ‘pseudocatalytical’ properties.