Metabolic Modeling Tutorial
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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: galactosyltransferase / raffinose synthase

Gene: RFS Accession Number: G-9595 (MetaCyc)

Synonyms: galactinol:sucrose 6-galactosyltransferase

Species: Pisum sativum

Summary:
A raffinose synthase (RFS) was partially purified from maturing seeds of pea (Pisum sativum) [Peterbauer02]; the gene encoding this protein was cloned and the protein expressed in a baculovirus expression system. The enzyme was tested both in its non-purified form (from the crude extract of baculovirus-infected insect cells) and in its partially-purified form: the same activity was demonstrated in both systems. The enzyme catalyzes the formation of raffinose from sucrose and galactinol. In addition to galactinol, the enzyme was able to use galactosylononitol; and sucrose could be replaced by D-ononitol or D-pinitol. In the latter case, the authors of the study did not specify whether the product of the reaction was galactopinitol A, galactopinitol B or a mixture of both [Peterbauer02]. Raffinose itself could not be used as an acceptor.

Molecular Weight of Polypeptide: 88.7 kD (from nucleotide sequence)

Unification Links: Entrez:CAD20127 , Protein Model Portal:Q8VWN6 , UniProt:Q8VWN6

Relationship Links: CAZy:IN-FAMILY:GH36 , InterPro:IN-FAMILY:IPR008811 , InterPro:IN-FAMILY:IPR013785 , InterPro:IN-FAMILY:IPR017853 , Pfam:IN-FAMILY:PF05691

Gene-Reaction Schematic: ?


Enzymatic reaction of: galactosyltransferase

EC Number: 2.4.1.-

D-ononitol + galactinol <=> D-galactosylononitol + myo-inositol

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.


Enzymatic reaction of: raffinose synthase

EC Number: 2.4.1.82

galactinol + sucrose <=> myo-inositol + raffinose

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

Alternative Substrates for sucrose: D-pinitol [Peterbauer02 ]

In Pathways: stachyose biosynthesis

Summary:
When expressed in the insect cell-baculovirus system, crude extracts containing the recombinant protein displayed raffinose synthase activity at 0.82 pkat.mg-1 soluble protein [Peterbauer02]. The specific activity of the partially purified enzyme from maturing seeds was 75.4 pkat.mg-1 protein.

Inhibitors (Competitive): 1,5-dideoxy-1,5-imino-D-galactitol [Peterbauer02] , myo-inositol [Peterbauer02]

Inhibitors (Other): Ni2+ [Peterbauer02]

Primary Physiological Regulators of Enzyme Activity: myo-inositol

Kinetic Parameters:

Substrate
Km (μM)
Citations
galactinol
7300.0
[Peterbauer02]
sucrose
22900.0
[Peterbauer02]

pH(opt): 7.0 [Peterbauer02]


References

Peterbauer02: Peterbauer T, Mach L, Mucha J, Richter A (2002). "Functional expression of a cDNA encoding pea (Pisum sativum L.) raffinose synthase, partial purification of the enzyme from maturing seeds, and steady-state kinetic analysis of raffinose synthesis." Planta 215(5);839-46. PMID: 12244450


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 Dec 18, 2014, biocyc12.