RESUMEN
Although the gasotransmitter hydrogen sulfide (H2S) is well known for its vasodilatory effects, H2S also exhibits vasoconstricting properties. Herein, it is demonstrated that administration of H2S as intravenous sodium sulfide (Na2S) increased blood pressure in sheep and rats, and this effect persisted after H2S has disappeared from the blood. Inhibition of the L-type calcium channel (LTCC) diminished the hypertensive effects. Incubation of Na2S with whole blood, red blood cells, methemoglobin, or oxyhemoglobin produced a hypertensive product of H2S, which is not hydrogen thioperoxide, metHb-SH- complexes, per-/poly- sulfides, or thiolsulfate, but rather a labile intermediate. One-electron oxidation of H2S by oxyhemoglobin generated its redox cousin, sulfhydryl radical (HSâ¢). Consistent with the role of HS⢠as the hypertensive intermediate, scavenging HS⢠inhibited Na2S-induced vasoconstriction and activation of LTCCs. In conclusion, H2S causes vasoconstriction that is dependent on the activation of LTCCs and generation of HS⢠by oxyhemoglobin.
Asunto(s)
Presión Sanguínea , Canales de Calcio Tipo L , Sulfuro de Hidrógeno , Oxihemoglobinas , Animales , Sulfuro de Hidrógeno/metabolismo , Sulfuro de Hidrógeno/farmacología , Oxihemoglobinas/metabolismo , Oxihemoglobinas/farmacología , Ratas , Canales de Calcio Tipo L/metabolismo , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Ovinos , Masculino , Hipertensión/metabolismo , Modelos Animales de Enfermedad , Sulfuros/farmacología , Sulfuros/metabolismoRESUMEN
Here, we present the second generation of our bicyclic peptide library (NTB), featuring a stereodiversified structure and a simplified construction strategy. We utilized a tandem ring-opening metathesis and ring-closing metathesis reaction (ROM-RCM) to cyclize the linear peptide library in a single step, representing the first reported instance of this reaction being applied to the preparation of macrocyclic peptides. Moreover, the resulting bicyclic peptide can be easily linearized for MS/MS sequencing with a one-step deallylation process. We employed this library to screen against the E363-R378 epitope of MYC and identified several MYC-targeting bicyclic peptides. Subsequent in vitro cell studies demonstrated that one candidate, NT-B2R, effectively suppressed MYC transcription activities and cell proliferation.