CHEN 3701 Lecture Notes - Lecture 20: Prostate-Specific Antigen, Prostate Cancer, Adsorption
20 Oct 2015
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Problem 1: some patients with prostate cancer have elevated levels of a protein called prostate specific antigen (psa) in the blood. A concentration above 2 ng/ml often leads to further evaluation although many factors, including psa dynamics, must be considered. You aim to develop a diagnostic test to quantify psa concentration from blood samples. You have a ligand that binds to psa with 0. 5 nm affinity. The association rate constant of the ligand for psa is 3*105 m-1s-1. You are characterizing a pilot version of your blood test using a patient"s blood sample. You adsorb 10 femtomoles of a ligand inside a test tube. 500 l of blood is added to the tube, and a long wait allows association and dissociation of the psa-ligand complex to near equilibrium. You rinse the tube to remove unbound psa while psa-ligand complex remains adsorbed. -> solving for [p]0 only unkonwn is [p]0. Plug in and solve --> [p]0 = 0. 047 nm.
