Synthesis and characterization of a model complex for flavodiiron NO reductases that stabilizes a diiron mononitrosyl complex

Hai T. Dong; Yu Zong; Abigail J. Bracken; Michael O. Lengel; Jeff W. Kampf; Debangsu Sil; Carsten Krebs; Nicolai Lehnert

doi:10.1016/j.jinorgbio.2022.111723

Synthesis and characterization of a model complex for flavodiiron NO reductases that stabilizes a diiron mononitrosyl complex

Hai T. Dong, Yu Zong, Abigail J. Bracken, Michael O. Lengel, Jeff W. Kampf, Debangsu Sil, Carsten Krebs, Nicolai Lehnert

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Abstract

Flavodiiron NO reductases (FNORs) are important enzymes in microbial pathogenesis, as they equip microbes with resistance to the human immune defense agent nitric oxide (NO). DFT calculations predict that a network of second coordination sphere (SCS) hydrogen bonds is critical for the key N[sbnd]N coupling step in the NO reduction reaction catalyzed by FNORs. In this study, we report the synthesis of a model complex of FNORs with pendant hydrogen bond donors. For this purpose, the ligand H[BPMP] (= 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol) was modified with two amide groups in the SCS. Reaction of the precursor complex [Fe₂(BPMP(NHCO^tBu)₂)(OAc)](OTf)₂ (1) (OTf⁻ = triflate anion) with NO in the presence of base led to the surprising isolation of a diiron mononitrosyl complex, [Fe₂(BPMP(NHCO^tBu)(NCO^tBu))(OAc)(NO)](OTf) (2) and a triiron decomposition product, [Fe₃(BPMP(NHCO^tBu)₂₎(OAc)₂(μ-O)₂(ONO)](OTf) (3), which were both structurally characterized. Complex 2 models the corresponding mononitrosyl adduct in FNORs. This result points towards a strategy that can be used to stabilize mononitrosyl diiron complexes, using the SCS.

Original language	English (US)
Article number	111723
Journal	Journal of Inorganic Biochemistry
Volume	229
DOIs	https://doi.org/10.1016/j.jinorgbio.2022.111723
State	Published - Apr 2022

All Science Journal Classification (ASJC) codes

Biochemistry
Inorganic Chemistry

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10.1016/j.jinorgbio.2022.111723

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@article{a8f174dff5cb41f5a3fb800defa05c25,

title = "Synthesis and characterization of a model complex for flavodiiron NO reductases that stabilizes a diiron mononitrosyl complex",

abstract = "Flavodiiron NO reductases (FNORs) are important enzymes in microbial pathogenesis, as they equip microbes with resistance to the human immune defense agent nitric oxide (NO). DFT calculations predict that a network of second coordination sphere (SCS) hydrogen bonds is critical for the key N[sbnd]N coupling step in the NO reduction reaction catalyzed by FNORs. In this study, we report the synthesis of a model complex of FNORs with pendant hydrogen bond donors. For this purpose, the ligand H[BPMP] (= 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol) was modified with two amide groups in the SCS. Reaction of the precursor complex [Fe2(BPMP(NHCOtBu)2)(OAc)](OTf)2 (1) (OTf− = triflate anion) with NO in the presence of base led to the surprising isolation of a diiron mononitrosyl complex, [Fe2(BPMP(NHCOtBu)(NCOtBu))(OAc)(NO)](OTf) (2) and a triiron decomposition product, [Fe3(BPMP(NHCOtBu)2)(OAc)2(μ-O)2(ONO)](OTf) (3), which were both structurally characterized. Complex 2 models the corresponding mononitrosyl adduct in FNORs. This result points towards a strategy that can be used to stabilize mononitrosyl diiron complexes, using the SCS.",

author = "Dong, {Hai T.} and Yu Zong and Bracken, {Abigail J.} and Lengel, {Michael O.} and Kampf, {Jeff W.} and Debangsu Sil and Carsten Krebs and Nicolai Lehnert",

note = "Publisher Copyright: {\textcopyright} 2022 Elsevier Inc.",

year = "2022",

month = apr,

doi = "10.1016/j.jinorgbio.2022.111723",

language = "English (US)",

volume = "229",

journal = "Journal of Inorganic Biochemistry",

issn = "0162-0134",

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TY - JOUR

T1 - Synthesis and characterization of a model complex for flavodiiron NO reductases that stabilizes a diiron mononitrosyl complex

AU - Dong, Hai T.

AU - Zong, Yu

AU - Bracken, Abigail J.

AU - Lengel, Michael O.

AU - Kampf, Jeff W.

AU - Sil, Debangsu

AU - Krebs, Carsten

AU - Lehnert, Nicolai

PY - 2022/4

Y1 - 2022/4

N2 - Flavodiiron NO reductases (FNORs) are important enzymes in microbial pathogenesis, as they equip microbes with resistance to the human immune defense agent nitric oxide (NO). DFT calculations predict that a network of second coordination sphere (SCS) hydrogen bonds is critical for the key N[sbnd]N coupling step in the NO reduction reaction catalyzed by FNORs. In this study, we report the synthesis of a model complex of FNORs with pendant hydrogen bond donors. For this purpose, the ligand H[BPMP] (= 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol) was modified with two amide groups in the SCS. Reaction of the precursor complex [Fe2(BPMP(NHCOtBu)2)(OAc)](OTf)2 (1) (OTf− = triflate anion) with NO in the presence of base led to the surprising isolation of a diiron mononitrosyl complex, [Fe2(BPMP(NHCOtBu)(NCOtBu))(OAc)(NO)](OTf) (2) and a triiron decomposition product, [Fe3(BPMP(NHCOtBu)2)(OAc)2(μ-O)2(ONO)](OTf) (3), which were both structurally characterized. Complex 2 models the corresponding mononitrosyl adduct in FNORs. This result points towards a strategy that can be used to stabilize mononitrosyl diiron complexes, using the SCS.

AB - Flavodiiron NO reductases (FNORs) are important enzymes in microbial pathogenesis, as they equip microbes with resistance to the human immune defense agent nitric oxide (NO). DFT calculations predict that a network of second coordination sphere (SCS) hydrogen bonds is critical for the key N[sbnd]N coupling step in the NO reduction reaction catalyzed by FNORs. In this study, we report the synthesis of a model complex of FNORs with pendant hydrogen bond donors. For this purpose, the ligand H[BPMP] (= 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol) was modified with two amide groups in the SCS. Reaction of the precursor complex [Fe2(BPMP(NHCOtBu)2)(OAc)](OTf)2 (1) (OTf− = triflate anion) with NO in the presence of base led to the surprising isolation of a diiron mononitrosyl complex, [Fe2(BPMP(NHCOtBu)(NCOtBu))(OAc)(NO)](OTf) (2) and a triiron decomposition product, [Fe3(BPMP(NHCOtBu)2)(OAc)2(μ-O)2(ONO)](OTf) (3), which were both structurally characterized. Complex 2 models the corresponding mononitrosyl adduct in FNORs. This result points towards a strategy that can be used to stabilize mononitrosyl diiron complexes, using the SCS.

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U2 - 10.1016/j.jinorgbio.2022.111723

DO - 10.1016/j.jinorgbio.2022.111723

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AN - SCOPUS:85123110975

SN - 0162-0134

VL - 229

JO - Journal of Inorganic Biochemistry

JF - Journal of Inorganic Biochemistry

M1 - 111723

ER -

Synthesis and characterization of a model complex for flavodiiron NO reductases that stabilizes a diiron mononitrosyl complex

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