Abstract: We isolated and purified high-purity and high-activity soluble Guanylate cyclase(sGC) from bovine lung. The electronic absorption and resonance Raman spectra of the ferrous and ferric forms of sGC were recorded. In the ferrous state of sGC, the electronic absorption spectra showed a sharp peak at 431 nm and a single broad peak in the α/β region at 559 nm. The resonance Raman spectra of sGC(ferrous) showed a stronger band at 1357 cm^-1 and a single peak at 1473 cm^-1 . For the ferric form of sGC, the Soret band was at 390 nm and resonance Raman peak was at 1375 cm^-1 . These spectra show that the heme-iron of the ferrous and ferric sGC are all 5-coordination and high spin.

Key words: Guanylate cyclase, Electronic absorption spectra, Resonance Raman spectra