diff --git a/studies/competition co-IP/protocols/coIP.txt b/studies/competition co-IP/protocols/coIP.txt
index a94dd4858b4b612f6a388bb05866a084c96cd728..20c992bc0cc53b224dba13eef130d5ca2ebe3db0 100644
--- a/studies/competition co-IP/protocols/coIP.txt	
+++ b/studies/competition co-IP/protocols/coIP.txt	
@@ -27,7 +27,7 @@ Cell harvest:
 18.	Ensure that your lysate is homogenous
 19.	Determine the protein concentration with Bradford from the total aliquot (dilute 10, 5, 2.5, 1.25, 0.625 µl lysate into 10 µl HKM-Lysis buffer; and add 800 µl 1xBradford reagent; incubate 5 min at RT and measure at 595nm; make a fresh Bradford series with BSA (8,4,2,1,0.5 µg).
 20.	Prepare 3x6 tubes for the different reactions, with 1200 µl lysate each or less if some is lost somewhere
-21.	Calculate how much of your 15N bait protein you need to add (0.25:1, 0.5:1, 1:1, 2.5:1, 5:1, 10:1 15N:14N)
+21.	Calculate how much of your 15N bait protein you need to add, assuming CPN20 accounts for 0.17% of the total protein and CPN60A for 0.1% of the total protein  (0.25:1, 0.5:1, 1:1, 2.5:1, 5:1, 10:1 15N:14N)
 22.	After the addition of the 15N protein take a 25 µl aliquot (freeze in -80°C)
 IP
 23.	To each reaction add 100µl slurry, let the beads bind the epitopes for 1h at 4°C