Kd Calculator

How to Use the Kd (Dissociation Constant) Calculator

Understanding the dissociation constant (Kd) is crucial in biochemistry and molecular biology as it provides insight into the affinity between a ligand and a protein. This step-by-step guide will help you accurately use the Kd Calculator to determine important values related to protein-ligand interactions.

Step 1: Input Total Protein Concentration

Begin by entering the total protein concentration in the designated field labeled Total Protein Concentration [P]t (M). You should input the concentration as a numerical value in molarity (M). Remember, this value is required and should be greater than or equal to zero. Use the placeholder as guidance.

• Validation: The protein concentration must be a non-negative number, and you can adjust it with a precision of 1e-12.

Step 2: Input Total Ligand Concentration

Next, locate the field labeled Total Ligand Concentration [L]t (M) and enter the corresponding ligand concentration in molarity. Similar to the protein concentration, this value is also essential and must be greater than or equal to zero.

• Validation: The ligand concentration must be a non-negative number with the ability to adjust by 1e-12 increments.

Step 3: Input Bound Fraction

Find the field labeled Bound Fraction and input the fraction of the ligand-protein complex that is bound. This value should be between 0 and 1, inclusive, representing the proportion of the total complex that is in the bound state.

• Validation: Ensure the bound fraction is a number between 0 and 1 and can be adjusted with a step size of 0.01.

Step 4: Review the Results

After filling all the input fields, the calculator will automatically compute and display the following results:

• Kd Value: This represents the dissociation constant, calculated using the formula ((1 – boundFraction) * proteinConcentration * (1 – boundFraction) * ligandConcentration) / boundFraction. The result will be presented with up to 12 decimal places and expressed in molarity (M).
• Bound Complex Concentration: Calculates the concentration of the bound complex using the formula boundFraction * min(proteinConcentration, ligandConcentration), formatted to 12 decimal places.
• Free Protein Concentration: This shows the amount of unbound protein remaining, found by proteinConcentration – (boundFraction * min(proteinConcentration, ligandConcentration)), with values seen up to 12 decimal places.
• Free Ligand Concentration: Represents residual free ligand in solution, calculated as ligandConcentration – (boundFraction * min(proteinConcentration, ligandConcentration)), displayed with 12 decimal places of precision.

Utilize these values to understand the binding dynamics in your experiments or analyses better. Adjust your input parameters if needed to explore different scenarios.