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Chemistry · Ch 10 — Surface Chemistry

Enzyme Catalysis

10.3

Enzyme Catalysis

Enzymes are complex protein molecules built around elaborate, precisely-folded three-dimensional structures, and it is this structure — not their chemical formula alone — that lets them catalyse the specific biochemical reactions occurring inside living organisms. Enzymes are frequently found in a colloidal state within the cell, and they are extremely specific in their catalytic action: each enzyme, synthesised within a particular living cell, is generally capable of catalysing only one particular reaction (or a very narrow family of closely related reactions). …

Table tbl-10.2Common examples of enzyme catalysis
EnzymeReaction catalysed
PepsinHydrolyses the peptide glycyl-L-glutamyl-L-tyrosine
DiastaseHydrolyses starch into maltose: 2(C6H10O5)n+nH2O→nC12H22O112(\text{C}_6\text{H}_{10}\text{O}_5)_n + n\text{H}_2\text{O} \rightarrow n\text{C}_{12}\text{H}_{22}\text{O}_{11}
Zymase (in yeast)Converts glucose into ethanol: C6H12O6→2C2H5OH+2CO2\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_2\text{H}_5\text{OH} + 2\text{CO}_2
Mycoderma acetiOxidises alcohol into acetic acid: C2H5OH+O2→CH3COOH+H2O\text{C}_2\text{H}_5\text{OH} + \text{O}_2 \rightarrow \text{CH}_3\text{COOH} + \text{H}_2\text{O}
Urease (present in soya beans)Hydrolyses urea: NH2-CO-NH2+H2O→2NH3+CO2\text{NH}_2\text{-CO-NH}_2 + \text{H}_2\text{O} \rightarrow 2\text{NH}_3 + \text{CO}_2