body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.calculator-container {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 25px;
margin-bottom: 40px;
box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.calc-header {
text-align: center;
margin-bottom: 25px;
}
.calc-header h3 {
margin: 0;
color: #2c3e50;
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
color: #495057;
}
.input-group input, .input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.row {
display: flex;
gap: 15px;
flex-wrap: wrap;
}
.col {
flex: 1;
min-width: 200px;
}
.btn-calc {
background-color: #28a745;
color: white;
border: none;
padding: 12px 20px;
width: 100%;
border-radius: 4px;
font-size: 16px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.2s;
margin-top: 10px;
}
.btn-calc:hover {
background-color: #218838;
}
.result-box {
background-color: #e8f5e9;
border: 1px solid #c3e6cb;
color: #155724;
padding: 20px;
border-radius: 4px;
margin-top: 20px;
text-align: center;
display: none;
}
.result-value {
font-size: 2em;
font-weight: bold;
display: block;
margin: 10px 0;
}
.mode-toggle {
margin-bottom: 20px;
text-align: center;
}
.mode-btn {
padding: 8px 16px;
background: #e2e6ea;
border: none;
cursor: pointer;
margin: 0 5px;
border-radius: 20px;
font-weight: 600;
font-size: 0.9em;
}
.mode-btn.active {
background: #28a745;
color: white;
}
.hidden {
display: none;
}
.article-content h2 {
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
margin-top: 30px;
}
.article-content ul {
background: #fff;
padding: 20px 40px;
border-left: 4px solid #28a745;
background-color: #f9f9f9;
}
.formula-box {
background: #f1f3f5;
padding: 15px;
border-radius: 4px;
font-family: monospace;
text-align: center;
margin: 20px 0;
font-size: 1.1em;
}
var currentMode = 'experimental';
function switchMode(mode) {
currentMode = mode;
var expSection = document.getElementById('sectionExperimental');
var mmSection = document.getElementById('sectionMM');
var btnExp = document.getElementById('btnModeExp');
var btnMM = document.getElementById('btnModeMM');
var resultBox = document.getElementById('resultBox');
resultBox.style.display = 'none';
if (mode === 'experimental') {
expSection.style.display = 'block';
mmSection.style.display = 'none';
btnExp.className = 'mode-btn active';
btnMM.className = 'mode-btn';
} else {
expSection.style.display = 'none';
mmSection.style.display = 'block';
btnExp.className = 'mode-btn';
btnMM.className = 'mode-btn active';
}
}
function calculateEnzymeRate() {
var resultBox = document.getElementById('resultBox');
var resultValue = document.getElementById('resultValue');
var resultUnit = document.getElementById('resultUnit');
var resultExplain = document.getElementById('resultExplain');
if (currentMode === 'experimental') {
var c1 = parseFloat(document.getElementById('conc1').value);
var c2 = parseFloat(document.getElementById('conc2').value);
var t1 = parseFloat(document.getElementById('time1').value);
var t2 = parseFloat(document.getElementById('time2').value);
var cUnit = document.getElementById('concUnit').value;
var tUnit = document.getElementById('timeUnit').value;
if (isNaN(c1) || isNaN(c2) || isNaN(t1) || isNaN(t2)) {
alert("Please enter valid numbers for all fields.");
return;
}
if (t2 === t1) {
alert("Time difference cannot be zero.");
return;
}
// Rate = (Change in Concentration) / (Change in Time)
var deltaC = c2 – c1;
var deltaT = t2 – t1;
var rate = deltaC / deltaT;
// Handle negative rate (substrate consumption)
var isNegative = rate < 0;
var absRate = Math.abs(rate);
resultValue.innerHTML = absRate.toFixed(4);
resultUnit.innerHTML = cUnit + "/" + tUnit;
if (isNegative) {
resultExplain.innerHTML = "Note: The negative slope (" + rate.toFixed(4) + ") indicates substrate consumption or disappearance.";
} else {
resultExplain.innerHTML = "Positive slope indicates product formation.";
}
} else {
// Michaelis-Menten Calculation
var vmax = parseFloat(document.getElementById('vmax').value);
var km = parseFloat(document.getElementById('km').value);
var s = parseFloat(document.getElementById('subsConc').value);
var unit = document.getElementById('mmUnit').value;
if (isNaN(vmax) || isNaN(km) || isNaN(s)) {
alert("Please enter valid numbers for Vmax, Km, and [S].");
return;
}
if ((km + s) === 0) {
alert("Denominator (Km + [S]) cannot be zero.");
return;
}
// V = (Vmax * [S]) / (Km + [S])
var velocity = (vmax * s) / (km + s);
resultValue.innerHTML = velocity.toFixed(4);
resultUnit.innerHTML = unit;
// Calculate saturation percentage
var saturation = (velocity / vmax) * 100;
resultExplain.innerHTML = "The enzyme is operating at
of its maximum velocity.";
}
resultBox.style.display = 'block';
}
How to Calculate Rate of Enzyme Reaction
Understanding how to calculate the rate of an enzyme reaction is fundamental in biochemistry and pharmacology. Reaction rate, often referred to as velocity ($V$), measures how fast an enzyme converts a substrate into a product. This metric is crucial for determining enzyme efficiency, investigating inhibition mechanisms, and optimizing industrial enzymatic processes.
There are two primary ways to calculate this rate: experimentally using data points (determining the slope) or theoretically using the Michaelis-Menten equation.
Method 1: Using Experimental Data (The Slope Method)
In a laboratory setting, reaction rates are typically calculated by measuring the change in concentration of a product or substrate over a specific time interval. This is often done using spectrophotometry to measure absorbance (OD).
Rate = Δ[Concentration] / ΔTime = ([C]₂ – [C]₁) / (t₂ – t₁)
Where:
- [C]₂: Final concentration of product (or remaining substrate).
- [C]₁: Initial concentration.
- t₂: Final time point.
- t₁: Initial time point.
Step-by-Step Example
Imagine you are measuring the production of a colored product.
At 0 minutes (t₁), the concentration is 0 µM (c₁).
At 5 minutes (t₂), the concentration is 25 µM (c₂).
The calculation would be:
Rate = (25 – 0) / (5 – 0) = 25 / 5 = 5 µM/min.
Note on Initial Velocity ($V_0$): Enzyme rates are not constant; they slow down as substrate is depleted. Therefore, it is best to calculate the rate during the linear phase (the very beginning of the reaction) to get the Initial Velocity ($V_0$).
Method 2: The Michaelis-Menten Equation
If you already know the kinetic parameters of the enzyme, you can calculate the expected rate at any given substrate concentration using the Michaelis-Menten equation. This model describes the rate of enzymatic reactions by relating reaction rate $V$ to $[S]$, the concentration of a substrate.
V = (Vₘₐₓ × [S]) / (Kₘ + [S])
- Vₘₐₓ (Maximum Velocity): The maximum rate achievable by the system at saturating substrate concentrations.
- Kₘ (Michaelis Constant): The substrate concentration at which the reaction rate is half of $V_{max}$. It is a measure of the enzyme's affinity for the substrate (lower $K_m$ = higher affinity).
- [S]: The current substrate concentration.
Factors Affecting Enzyme Reaction Rates
When calculating and analyzing rates, keep these variables in mind:
- Temperature: Rates generally increase with temperature until the enzyme denatures.
- pH: Enzymes have an optimal pH range; deviating from this reduces activity.
- Substrate Concentration: Adding more substrate increases the rate until the enzyme becomes saturated ($V_{max}$).
- Enzyme Concentration: The rate is directly proportional to the amount of enzyme present, assuming substrate is in excess.
Common Units of Measurement
Ensure your units are consistent before calculating:
- Concentration: Molar (M), Millimolar (mM), Micromolar (µM).
- Time: Seconds (s), Minutes (min).
- Activity: International Units (U) or Katals (kat). 1 U = 1 µmol/min.