Interaction of Soluble Guanylate Cyclase with YC-1: Kinetic and Resonance Raman Studies
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- 作者：John W. Denninger ; Johannes P. M. Schelvis ; Philip E. Brandish ; Yunde Zhao ; Gerald T. Babcock ; and Michael A. Marletta
- 刊名：Biochemistry
- 出版年：2000
- 出版时间：April 11, 2000
- 年：2000
- 卷：39
- 期：14
- 页码：4191 - 4198
- 全文大小：90K
- 年卷期：v.39,no.14(April 11, 2000)
- ISSN：1520-4995
文摘
The enzyme-soluble guanylate cyclase (sGC), which converts GTP to cGMP, is a receptor forthe signaling agent nitric oxide (NO). YC-1, a synthetic benzylindazole derivative, has been shown toactivate sGC in an NO-independent fashion. In the presence of carbon monoxide (CO), which by itselfactivates sGC approximately 5-fold, YC-1 activates sGC to a level comparable to stimulation by NOalone. We have used kinetic analyses and resonance Raman spectroscopy (RR) to investigate the interactionof YC-1 and CO with guanylate cyclase. In the presence of CO and 200 
es/entities/mgr.gif">M YC-1, the Vmax/Km GTPincreases 226-fold. While YC-1 does not perturb the RR spectrum of the ferrous form of baculovirus/Sf9cell expressed sGC, it induces a shift in the Fe-CO stretching frequency for the CO-bound form from474 to 492 cm-1. Similarly, YC-1 has no effect on the RR spectrum of ferrous es/gifchars/beta2.gif" BORDER=0 ALIGN="middle">11-385, the isolated sGCheme-binding domain, but shifts the es/gifchars/nu.gif" BORDER=0 >(Fe-CO) of CO-es/gifchars/beta2.gif" BORDER=0 ALIGN="middle">11-385 from 478 to 491 cm-1, indicating thatYC-1 binds in heme-binding region of sGC. In addition, the CO-bound forms of sGC and es/gifchars/beta2.gif" BORDER=0 ALIGN="middle">11-385 in thepresence of YC-1 lie on the es/gifchars/nu.gif" BORDER=0 >(Fe-CO) vs es/gifchars/nu.gif" BORDER=0 >(C-O) correlation curve for proximal ligands with imidazolecharacter, which suggests that histidine remains the heme proximal ligand in the presence of YC-1.Interestingly, YC-1 does not shift es/gifchars/nu.gif" BORDER=0 >(Fe-CO) for the CO-bound form of H105G(Im), the imidazole-rescuedheme ligand mutant of es/gifchars/beta2.gif" BORDER=0 ALIGN="middle">11-385. The data are consistent with binding of CO and YC-1 to the sGC heme-binding domain leading to conformational changes that give rise to an increase in catalytic turnover anda change in the electrostatic environment of the heme pocket.