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Literature summary for 1.7.2.1 extracted from

  • Hedison, T.M.; Shenoy, R.T.; Iorgu, A.I.; Heyes, D.J.; Fisher, K.; Wright, G.S.A.; Hay, S.; Eady, R.R.; Antonyuk, S.V.; Hasnain, S.S.; Scrutton, N.S.
    Unexpected roles of a tether harboring a tyrosine gatekeeper residue in modular nitrite reductase catalysis (2019), ACS Catal., 9, 6087-6099 .
    View publication on PubMedView publication on EuropePMC
Search for more literature for 1.7.2.1

Protein Variants

Protein Variants Comment Organism
Y323A about 90% of wild-type activity. Tether residue Tyr 323 is a gatekeeper for nitrite binding. The water molecules occupying free space above type 2 copper are connected by strong hydrogen bonds, while the channel space, opposite to the NiR-core, is open and contains full occupancy waters Ralstonia pickettii
Y323E about 90% of wild-type activity. Tether residue Tyr 323 is a gatekeeper for nitrite binding. The water molecules occupying free space above type 2 copper are connected by strong hydrogen bonds, while the channel space, opposite to the NiR-core, is open and contains full occupancy waters Ralstonia pickettii
Y323F about 90% of wild-type activity. Tether residue Tyr 323 is a gatekeeper for nitrite binding. Mutant has a single water, W1, bound to the type 2 copper site Ralstonia pickettii

Inhibitors

Inhibitors Comment Organism Structure
nitrite
-
 Ralstonia pickettii

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.0016
-
 nitrite wild-type, pH 6.5, 25°C Ralstonia pickettii
0.29
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii
0.41
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii

Metals/Ions

Metals/Ions Comment Organism Structure
copper tethering does not enhance the rate of electron delivery from its pendant cytochrome c to the catalytic copper-containing core. Tethering communicates the redox state of the heme to the distant type 2 copper center that helps initiate substrate binding for catalysis. It also tunes copper reduction potentials, suppresses reductive enzyme inactivation, enhances enzyme affinity for substrate, and promotes inter-copper electron transfer Ralstonia pickettii

Organism

Organism UniProt Comment Textmining
Ralstonia pickettii B2UHR8
-
-
Ralstonia pickettii 12J B2UHR8
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
nitrite + reduced phenazine methosulfate
-
 Ralstonia pickettii NO + oxidized phenazine methosulfate
-
 ?
nitrite + reduced phenazine methosulfate
-
 Ralstonia pickettii 12J NO + oxidized phenazine methosulfate
-
 ?

Synonyms

Synonyms Comment Organism
NiR
-
 Ralstonia pickettii
Rpic_4015
-
 Ralstonia pickettii

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
1.1
-
 nitrite wild-type, pH 6.5, 25°C Ralstonia pickettii
2.3
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii
2.6
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
130
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii
160
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii

General Information

General Information Comment Organism
metabolism tethering does not enhance the rate of electron delivery from its pendant cytochrome c to the catalytic copper-containing core. Tethering communicates the redox state of the heme to the distant type 2 copper center that helps initiate substrate binding for catalysis. It also tunes copper reduction potentials, suppresses reductive enzyme inactivation, enhances enzyme affinity for substrate, and promotes inter-copper electron transfer. Nitrite binding and enzyme turnover is controlled by heme reduction and prevents NiR inactivation Ralstonia pickettii

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
5.6
-
 nitrite core protein, pH 6.5, 25°C Ralstonia pickettii
8.8
-
 nitrite core protein carrying mutation Y327F, pH 6.5, 25°C Ralstonia pickettii
690
-
 nitrite wild-type, pH 6.5, 25°C Ralstonia pickettii