UNIT 10.5 Measurement of cGMP and Soluble Guanylyl Cyclase Activity

  1. Eric Southam

Published Online: 1 MAY 2001

DOI: 10.1002/0471140856.tx1005s04

Current Protocols in Toxicology

Current Protocols in Toxicology

How to Cite

Southam, E. 2001. Measurement of cGMP and Soluble Guanylyl Cyclase Activity. Current Protocols in Toxicology. 00:10.5:10.5.1–10.5.8.

Author Information

  1. Glaxo Wellcome Medicines Research Center, Stevenage, United Kingdom

Publication History

  1. Published Online: 1 MAY 2001
  2. Published Print: MAY 1999


Soluble guanylyl cyclase is responsible for synthesis of guanosine 3'5'-cyclic monophosphate. The enzyme is activated by NO, so measurement of tissue levels of cGMP and the activity of guanylyl cyclase is important in studies of NO-cGMP signal transduction. The method of choice for measuring tissue levels of cGMP is a radioimmunoassay, but it can also be measured using a scintillation proximity assay. Guanylyl cyclase activity is determined by measuring the conversion of GTP to cGMP using a radioimmunoassay or by following the conversion of [32P]GTP to [32P]cGMP, with separation of the product by precipitation and chromatography on an alumina column.