How to Calculate PA2 Value

••• Comstock/Comstock/Getty Images

In the field of biochemistry, a pA2 value determines the important relationship between two drugs "competing" for effect on the same receptor. The "agonist" drug tries to affect the receptor. The "antagonist" drug attempts to block the agonist from working. The two drugs are "competitive" if increasing or reducing one drug decreases or increases the effect of the other, respectively. The pA2 value indicates the concentration of antagonist when double the agonist is required to have the same effect on the receptor as when no antagonist is present.

    Calculate the base-10 logarithm of Kd. When we say log ("base 10") of x equals y, we mean that 10^y equals x. For example, log of 100 equals 2, log of 1,000 equals 3, and so forth. If Kd is 5, then use your calculator to see that log 5 approximately equals 0.7.

    Multiply the result by negative one. Using our previous example, the product of 0.7 and -1 equals -0.7.

    Check the result, which is the pA2 value.

    Tips

    • The "p" in pA2 indicates its logarithmic scale, just like "pH." The "A" is for "antagonist." Lastly, the "2" is for dose ratio of increased agonist to original agonist concentration to counteract the antagonist.

Related Articles

How to Calculate Significance
How to Calculate Cost Increase by a Percent
How to Use the Pearson Correlation Coefficient
How to Convert Ng/Ml to IU
How to Find Y Value for the Slope of a Line
How is Calculus Used in Economics?
How to Enter a Subscript on the TI-83
What Is a Non Linear Relationship?
How to Find Partial Pressures
The Purpose of Statistical Analysis: Mean & Standard...
Beat Frequencies: Definition, Formula & Applications...
How to Calculate the Wronskian
How to Calculate dB Loss
How to Multiply Vectors
What Are the Functions of TSH?
How to Interpret a Beta Coefficient
How to Find the X Intercept of a Function
How to Calculate a P-Value
How to Calculate the T Test Value
Why Should You Only Test for One Variable at a Time...

Dont Go!

We Have More Great Sciencing Articles!