Enzymatic and Non-Enzymatic Response during Nitrosative Stress in Escherichia coli
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25 jun 2022
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Publicado en línea: 25 jun 2022
Páginas: 81 - 93
Recibido: 01 nov 2021
Aceptado: 01 abr 2022
DOI: https://doi.org/10.2478/am-2022-0008
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© 2022 Rohan Nath et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Fig. 1
![Mechanism of action of flavohemoglobin under aerobic and anaerobic condition in presence of nitrating agentUnder aerobic condition Fe(II) present in Hmp remains associated with O2 to form Fe(II) O2 complex. Under nitrosative stress in presence of NO, it forms nitrosyldioxyl complex (Fe[II]OONO) and this complex ultimately breaks down to nitrate (NO3−) and heme group returns back to its original state [Fe(III)]. Under anaerobic condition, NO• reacts with Fe(II) and Fe(III)NO− is formed. Fe(III)NO− is again broken down to NO− and then it is converted to N2O via dimeric species.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647092df71e4585e08aa03af/j_am-2022-0008_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250910%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250910T214438Z&X-Amz-Expires=3600&X-Amz-Signature=e367de6f892c12d5cb95996f0f566678cffcfcda7730107d7225822be513e67e&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 2

Fig. 3
![Mechanism of action of flavorubredoxinNO• can be reduced to N2O by two mechanisms involving the [Fe2+-O-Fe2+]. (A) via formation of NO2−, (B) Formation of N2O from NO• via formation of [Fe3+-O-Fe3+-NO2−] as intermediate.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647092df71e4585e08aa03af/j_am-2022-0008_fig_003.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250910%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250910T214438Z&X-Amz-Expires=3600&X-Amz-Signature=ff73f31c71f9ef79f4cc3f6c4d570050f57b3f504737c605d9a4e2cf48d24035&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 4
![Mechanism of action of catalaseCatalase has the Fe(III) center which helps in quenching of nitric oxide and peroxynitrite. When catalase encounters NO•, Compound I ([Cat-Fe(IV) = O]+·) is formed due to oxidation by NO•. When such Compound I again reacts with another NO•, nitrite (NO2−) is formed as end product. On the other hand, when catalase encounters peroxynitrite ((ONOOH), Compound II ([Cat-Fe(IV) = O+·NO2]) is formed which breaks down to nitrite (NO3−).](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647092df71e4585e08aa03af/j_am-2022-0008_fig_004.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250910%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250910T214438Z&X-Amz-Expires=3600&X-Amz-Signature=f04adb8e98d8d4e2b2a61e9fee082cdcb73eaa2a70cd7ce1313becb8545010f4&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 5

Fig. 6

Fig. 7
![Predicted mechanism of action of hybrid cluster proteinThis predicted figure shows the mode of action of Hcp via two different mechanisms. In one pathway, the [4Fe2+-2S-2O] containing Hcp can react with NO and Fe2+ is oxidized to Fe3+with the formation of NO2−. NO2− can again react with another NO2− and N2O is formed as the end product. In another mechanism, [2Fe2+−2S] containing Hcp can react with NO and NH2OH (hydroxylamine) is formed which may get converted to ammonia (NH3). In this reaction also Fe2+ is oxidized to Fe3+ but it can again come back to its normal state.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647092df71e4585e08aa03af/j_am-2022-0008_fig_007.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20250910%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20250910T214438Z&X-Amz-Expires=3600&X-Amz-Signature=67d1c29a4390d901ae646dc39c301259c91fcd68fca2d0166f35677156b7717c&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Fig. 8
