Former Chromogenix substrate S-2586 now has as an identical replacement product, DiaPharma CS – PSA (KLK3), product number DPG586-25.

DiaPharma CS – PSA (KLK3) is a chromogenic peptide substrate for chymotrypsin and prostate specific antigen (PSA). DiaPharma CS – PSA (KLK3) may be used for assaying (1) purified preparations of chymotrypsin, (2) chymotrypsin-like activity in biological samples, and (3) anti-chymotrypsin in blood plasma. A chymotrypsin activity research method using substrate MeO-Suc-Arg-Pro-Tyr-pNA is available.

Research also suggests that the MeO-Suc-Arg-Pro-Tyr-pNA chromogenic substrate can be used in researching enzymatic prostate-specific antigen (PSA) activity. PSA is a chymotrypsin-like serine protease belonging to the human kallikrein family, specifically known as kallikrein-related peptidase 3 (KLK3). Although antigen is used in the name and PSA is best known in researching prostate cancer, PSA is an active enzyme that is produced at high levels in prostate cancer, but the role of its serine protease activity in prostate cancer remains a mystery.

Each vial contains chromogenic substrate MeO-Suc-Arg-Pro-Tyr-pNA • HCl 25 mg and mannitol 40 mg added as a bulking agent.

MeO-Suc-Arg-Pro-Tyr-pNA • HCl

MW: 668.29 (without HCl salt)

MeO-Suc-Arg-Pro-Tyr-pNA + E
MeO-Suc-Arg-Pro-Tyr-OH + pNA + E

E = Enzyme

S-2586 was originally used to study chymotrypsin activity:

The chymotrypsin activity is determined by its amidolytic effect on the substrate MeO-Suc-Arg-Pro-Tyr-pNA (S-2586). The rate at which p-nitroaniline (pNA) is released is measured photometrically at 405 nm. This can be followed on a recorder (initial rate method) or read after stopping the reaction with acetic acid (acid stopped method). The correlation between the change in absorbance per minute (DA/min) or absorbance (A) and the chymotrypsin activity is linear in the 0.05-1.0 µkat/l or 3-60 U/l range. The amidolytic activity of different chymotrypsin preparations does not necessarily parallel the protease activity.

Prostate-specific antigen is a “chymotrypsin-like” serine protease:

PSA is best known as a prostate cancer biomarker. It is a serine protease that belongs to the human kallikrein family and possess a specificity similar to chymotrypsin. Therefore, many studies have shown that this chromogenic substrate can be used for studying PSA enzyme activity. PSA may be an attractive target in prostate cancer, and therefore PSA inhibitors may represent a promising class of research compounds. The inhibition of of proteolytic activity of PSA by inhibitors can be measured using MeO-Suc-Arg-Pro-Tyr-pNA substrates.