A positive myocardial inotropic effect achieved using HNO/NO(-) , compared with NO⋅, triggered attempts to explore novel nitroxyl donors for use in clinical applications in vascular and myocardial pharmacology. To develop M-NO complexes for nitroxyl chemistry and biology, modulation of direct nitroxyl-transfer reactivity of dinitrosyl iron complexes (DNICs) is investigated in this study using a Fe(III) -porphyrin complex and proteins as a specific probe. Stable dinuclear {Fe(NO)2 }(9) DNIC [Fe(μ-(Me) Pyr)(NO)2 ]2 was discovered as a potent nitroxyl donor for nitroxylation of Fe(III) -heme centers through an associative mechanism. Beyond the efficient nitroxyl transfer, transformation of DNICs into a chemical biology probe for nitroxyl and for pharmaceutical applications demands further efforts using in vitro/in vivo studies.

Rabbit is a unique species to study human embryology; however, there are limited reports on the key transcription factors and epigenetic events of rabbit embryos. This study examined the Oct-4 and acetylated H4K5 (H4K5ac) patterns in rabbit embryos using immunochemistry staining. The average intensity of the Oct-4 signal in the nuclei of the whole embryo spiked upon fertilization, then decreased until the 8-cell stage and increased afterwards until the compact morula (CM) stage. It decreased thereafter from the CM stage to the early blastocyst (EB) stage, with a minimum at the expanded blastocyst (EXPB) stage and came back to a level similar to that of the CM-stage embryos in the hatching blastocysts (HB). The Oct-4 signal was observed in both the inner cell mass (ICM) and the trophectoderm (TE) cells of blastocysts. The average H4K5ac signal intensity of the whole embryo increased upon fertilization, started to decrease at the 4-cell stage, reached a minimum at the 8-cell stage, increased again at the EXPB stage and peaked at the HB stage. While TE cells maintained similar levels of H4K5ac throughout the blastocyst stages, ICM cells of HB showed higher levels of H4K5ac than those of EB and EXPB.

Mononuclear, distorted trigonal bipyramidal [PPN][Ni(III)(R)(P(C(6)H(3)-3-SiMe(3)-2-S)(3))] (R = Me (1); R = Et (2)) were prepared by reaction of [PPN][Ni(III)Cl(P(C(6)H(3)-3-SiMe(3)-2-S)(3))] and CH(3)MgCl/C(2)H(5)MgCl, individually. EPR, SQUID studies as well as DFT computations reveal that the Ni(III) in 1 has a low-spin d(7) electronic configuration in a distorted trigonal bipyramidal ligand field. The Ni-C bond lengths of 1.994(3) A in 1 and 2.015(3) A in 2 are comparable to that in the Ni(III)-methyl state of MCR (approximately 2.04 A) (Sarangi, R.; Dey, M.; Ragsdale, S. W. Biochemistry 2009, 48, 3146). Under a CO atmosphere, CO triggers homolytic cleavage of the Ni(III)-CH(3) bond in 1 to produce Ni(II)-thiolate carbonyl [PPN][Ni(II)(CO)(P(C(6)H(3)-3-SiMe(3)-2-S)(3))] (3). Additionally, protonation of 1 with phenylthiol generates Ni(III)-thiolate [PPN][Ni(III)(SPh)(P(C(6)H(3)-3-SiMe(3)-2-S)(3))] (4).