Variables
Description
What is this formula?
Fractional enzyme saturation describes the fraction of enzyme active sites occupied by substrate molecules.
The value ranges from 0 to 1:
θ = 0 means no active sites are occupied.
θ = 1 means all active sites are occupied.
At S = Km, the enzyme is 50% saturated.
When to use it
Use this formula when studying enzyme-substrate binding, enzyme kinetics, substrate affinity, and catalytic behavior.
Example
An enzyme has:
Km = 2 mmol/L
S = 6 mmol/L
Formula:
θ = S/(Km + S)
Substitution:
θ = 6/(2 + 6)
θ = 0.75
Result:
75% of enzyme active sites are occupied by substrate.
Applications
- Enzyme kinetics
- Biochemistry
- Molecular biology
- Biotechnology
- Drug development
- Metabolic pathway analysis
- Enzyme characterization
Note
This equation assumes Michaelis–Menten behavior and independent binding of substrate molecules. It does not describe cooperative enzymes, allosteric effects, or complex multi-site interactions. For cooperative systems, the Hill equation is often more appropriate.