Format

Send to

Choose Destination
See comment in PubMed Commons below
Anal Biochem. 2002 Apr 1;303(1):49-56.

Continuous spectrometric assays for glutaminyl cyclase activity.

Author information

1
Laboratory of Biochemistry, probiodrug AG, Weinbergweg 22, 06120 Halle/Saale, Germany.

Abstract

The enzymatic conversion of one chromogenic substrate, l-glutamine-p-nitroanilide, and two fluorogenic substrates, l-glutaminyl-2-naphthylamide and l-glutaminyl-4-methylcoumarinylamide, into their respective pyroglutamic acid derivatives by glutaminyl cyclase (QC) was estimated by introducing a new coupled assay using pyroglutamyl aminopeptidase as the auxiliary enzyme. For the purified papaya QC, the kinetic parameters were found to be in the range of those previously reported for other glutaminyl peptides, such as Gln-Gln, Gln-Ala, or Gln-tert-butyl ester. The assay can be performed in the presence of ammonia up to a concentration of 50 mM. Increasing ionic strength, e.g., potassium chloride up to 300 mM, resulted in an increase in enzymatic activity of about 20%. This is the first report of a fast, continuous, and reliable determination of QC activity, even in the presence of ammonium ions, during the course of protein purification and enzymatic analysis.

PMID:
11906150
DOI:
10.1006/abio.2001.5560
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center