Native human nitric oxide sensitive guanylyl cyclase: purification and characterization

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Previous purification of native human soluble guanylyl cyclase (sGC) used placenta, yielding an enzyme with low NO-activation and a hexa-coordinate heme group.
• This placental enzyme's properties contrasted with subsequently studied recombinant human sGC enzymes.
• A native, functional, nitric oxide (NO)-sensitive human sGC had not been successfully purified from alternative sources.

Purpose of the Study:

• To purify and characterize native human sGC from a different source (platelets) to investigate discrepancies observed with the placental enzyme.
• To determine if the differences between native placental sGC and recombinant sGC are a general phenomenon.
• To obtain an enzyme preparation relevant for developing novel antiplatelet and antianginal drugs.

Main Methods:

• Purification of native human soluble guanylyl cyclase (sGC) from human platelets.
• Characterization of the purified enzyme's properties, including NO sensitivity and heme group coordination state.

Main Results:

• Successful purification and characterization of native human alpha(1)/beta(1) soluble guanylyl cyclase (sGC) from platelets.
• The platelet enzyme is a highly NO-sensitive, heterodimeric enzyme.
• In contrast to the placental enzyme, the native platelet sGC contains a ferrous, penta-coordinate heme group, consistent with recombinant enzyme findings.

Conclusions:

• This study reports the first successful purification and characterization of the native human alpha(1)/beta(1) isoform of soluble guanylyl cyclase (sGC).
• The native platelet sGC exhibits properties aligning with recombinant enzymes, suggesting placental enzyme findings may be specific.
• The purified native platelet sGC is a relevant target for cardiovascular drug development, particularly for antiplatelet and antianginal therapies.