Calculate the average rate based on product concentration change over time.
2. Michaelis-Menten Velocity
Predict the reaction rate (v) using enzyme kinetic parameters.
Understanding Enzyme Reaction Rates
The rate of an enzyme reaction (or velocity, v) measures how quickly an enzyme converts substrates into products. In biochemistry, this is typically expressed as the change in concentration over a specific time period.
How to Calculate the Rate
The simplest way to determine the reaction rate is to measure the appearance of a product or the disappearance of a substrate over time:
Rate = Δ[Product] / ΔTime
The Michaelis-Menten Equation
For more complex kinetic analysis, scientists use the Michaelis-Menten equation, which describes how the reaction rate varies with substrate concentration:
v = (Vmax * [S]) / (Km + [S])
Vmax: The maximum rate achieved by the system at saturating substrate concentrations.
Km (Michaelis Constant): The substrate concentration at which the reaction rate is half of Vmax. It indicates the affinity of the enzyme for its substrate.
[S]: The concentration of the substrate.
Example Calculation
If an enzyme has a Vmax of 100 μmol/min and a Km of 5 mM, what is the rate when the substrate concentration [S] is 10 mM?
Using the formula: v = (100 * 10) / (5 + 10) = 1000 / 15 = 66.67 μmol/min.
function calculateBasicRate() {
var p = parseFloat(document.getElementById('deltaP').value);
var t = parseFloat(document.getElementById('deltaTime').value);
var resDiv = document.getElementById('basicResult');
if (isNaN(p) || isNaN(t) || t <= 0) {
resDiv.style.display = "block";
resDiv.style.color = "#c0392b";
resDiv.innerHTML = "Error: Please enter valid numbers. Time must be greater than zero.";
return;
}
var rate = p / t;
resDiv.style.display = "block";
resDiv.style.color = "#2c3e50";
resDiv.innerHTML = "Reaction Rate: " + rate.toFixed(4) + " units/secFormula used: Δ[P] / Δt";
}
function calculateMMRate() {
var vmax = parseFloat(document.getElementById('vmax').value);
var km = parseFloat(document.getElementById('km').value);
var s = parseFloat(document.getElementById('substrateS').value);
var resDiv = document.getElementById('mmResult');
if (isNaN(vmax) || isNaN(km) || isNaN(s) || (km + s) === 0) {
resDiv.style.display = "block";
resDiv.style.color = "#c0392b";
resDiv.innerHTML = "Error: Please enter valid positive values for Vmax, Km, and [S].";
return;
}
var velocity = (vmax * s) / (km + s);
resDiv.style.display = "block";
resDiv.style.color = "#2c3e50";
resDiv.innerHTML = "Predicted Velocity (v): " + velocity.toFixed(4) + " units/timeFormula: (Vmax * [S]) / (Km + [S])";
}