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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Enzyme: D-galacturonate reductase

Species: Euglena gracilis Z

Summary:
The apparent molecular mass of the enzyme was determined to be 38 kDa by SDS-PAGE and 39 kDa by gel filtration chromatography, indicating that it is a monomer in its native state [Ishikawa06].

The substrate specificity and the animo-terminal sequence of the enzyme were shown to be distinct from the D-galacturonate reductases from strawberry and mold [Ishikawa06].

Molecular Weight of Polypeptide: 38.0 kD (experimental) [Ishikawa06 ]

Gene-Reaction Schematic: ?

Credits:
Created 08-Jan-2010 by Fulcher CA , SRI International


Enzymatic reaction of: D-galacturonate reductase

Synonyms: D-galacturonic acid reductase

EC Number: 1.1.1.365

aldehydo-D-galacturonate + NADPH + H+ <=> aldehydo-L-galactonate + NADP+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

The reaction is irreversible in the direction shown. [Ishikawa06]

Alternative Substrates for aldehydo-D-galacturonate: α-D-xylopyranose [Ishikawa06 ] , D-glucuronate [Ishikawa06 ] , β-L-galactose [Ishikawa06 ] , D-galactose [Ishikawa06 ] , D-glucose [Ishikawa06 ] , L-arabinose [Ishikawa06 ] , DL-glyceraldehyde [Ishikawa06 ]

In Pathways: L-ascorbate biosynthesis V

Summary:
The reaction product aldehydo-L-galactonate was identified by HPLC. The enzyme could use both NADPH and NADH in a ratio of 10 to 1.8, respectively indicating a preference for NADPH. The enzyme showed a broad substrate specificity, but highest catalytic efficiency for D-galacturonate and D-glucuronate. Neither menadione nor 4-nitrobenzaldehyde could serve as substrates. In vitro the enzyme could not use aldehydo-L-galactonate and NADP+ as substrate in the reverse direction. The enzyme appeared to be activated in the presence of hydrogen peroxide, a compound involved in redox homeostasis in the cell [Ishikawa06].

Kinetic Parameters:

Substrate
Km (μM)
Citations
NADPH
62.5
[Ishikawa06]

pH(opt): 7.2 [Ishikawa06]


References

Ishikawa06: Ishikawa T, Masumoto I, Iwasa N, Nishikawa H, Sawa Y, Shibata H, Nakamura A, Yabuta Y, Shigeoka S (2006). "Functional characterization of D-galacturonic acid reductase, a key enzyme of the ascorbate biosynthesis pathway, from Euglena gracilis." Biosci Biotechnol Biochem 70(11);2720-6. PMID: 17090924

Richard09: Richard P, Hilditch S (2009). "D-galacturonic acid catabolism in microorganisms and its biotechnological relevance." Appl Microbiol Biotechnol 82(4);597-604. PMID: 19159926


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Thu Nov 27, 2014, biocyc13.