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Literature summary for 1.8.1.2 extracted from

  • Askenasy, I.; Murray, D.T.; Andrews, R.M.; Uversky, V.N.; He, H.; Stroupe, M.E.
    Structure-function relationships in the oligomeric NADPH-dependent assimilatory sulfite reductase (2018), Biochemistry, 57, 3764-3772 .
    View publication on PubMed
Search for more literature for 1.8.1.2

Cloned(Commentary)

Cloned (Comment) Organism
expressed in LMG194 Escherichia coli cells Escherichia coli

Protein Variants

Protein Variants Comment Organism
F496D variants of the flavin binding reductase (SiRFP) shows reduced activity compared to that of the wild-type enzyme Escherichia coli
V500D variant of the flavin binding reductase (SiRFP) binds NADP+ with an affinity similar to that of wild-type enzyme. The variant is reduced by about 60% in its ability to transfer electrons to the iron-containing oxidase (SiRHP). Escherichia coli
Y101A variants of the flavin binding reductase (SiRFP) shows reduced activity compared to that of the wild-type enzyme Escherichia coli

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
sulfite + 3 NADPH + 3 H+ Escherichia coli essential enzyme in the global sulfur cycle hydrogen sulfide + 3 NADP+ + 3 H2O
-
 ?

Organism

Organism UniProt Comment Textmining
Escherichia coli
-
-
-

Purification (Commentary)

Purification (Comment) Organism
-
 Escherichia coli

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
sulfite + 3 NADPH + 3 H+
-
 Escherichia coli hydrogen sulfide + 3 NADP+ + 3 H2O
-
 ?
sulfite + 3 NADPH + 3 H+ essential enzyme in the global sulfur cycle Escherichia coli hydrogen sulfide + 3 NADP+ + 3 H2O
-
 ?

Subunits

Subunits Comment Organism
dodecamer NADPH-dependent assimilatory sulfite reductase (SiR) is composed of two subunits. One is a multidomain flavin binding reductase (SiRFP) and the other an iron-containing oxidase (SiRHP). Tight binding between SiRFP and SiRHP is incompatible with the electron transfer-competent interface, suggesting that the dodecameric holoenzyme consists of four SiRFP/SiRHP heterodimers and four free SiRFP molecules. Six electrons come two at a time from three NADPH cofactors to complete catalysis, which means that SiRHP must interact with SiRFP three times for every SO3(2-) that binds Escherichia coli

Synonyms

Synonyms Comment Organism
NADPH-dependent assimilatory sulfite reductase
-
 Escherichia coli
SIR
-
 Escherichia coli

General Information

General Information Comment Organism
physiological function essential enzyme in the global sulfur cycle Escherichia coli