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Literature summary for 2.4.1.21 extracted from
- Comparative invitro analyses of recombinant maize starch synthases SSI, SSIIa, and SSIII reveal direct regulatory interactions and thermosensitivity (2016), Arch. Biochem. Biophys., 596, 63-72.
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| Glucan | stimulates the isoform SSIIa and SSIII reaction rates | Zea mays |  |
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| expressed in Escherichia coli Rosetta2 (DE3) pLysS cells | Zea mays |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 0.33 | - |
ADP-alpha-D-glucose | free isoform SSIII, at pH 8.0 and 30°C | Zea mays | |
| 0.39 | - |
ADP-alpha-D-glucose | free isoform SSI, at pH 8.0 and 30°C | Zea mays | |
| 0.84 | - |
ADP-alpha-D-glucose | free isoform SSIIa, at pH 8.0 and 30°C | Zea mays | |
Molecular Weight [Da]
| Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|
| 70000 | - |
x * 70000, isoform SSI, calculated from amino acid sequence | Zea mays |
| 77000 | - |
x * 77000, isoform SSIIa, calculated from amino acid sequence | Zea mays |
| 180000 | - |
x * 180000, isoform SSIII, calculated from amino acid sequence | Zea mays |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Zea mays | - |
- |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| Ni-NTA agarose column chromatography, and gel filtration | Zea mays |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 6.16 | - |
free isoform SSI, at pH 8.0 and 30°C | Zea mays |
| 6.33 | - |
free isoform SSIII, at pH 8.0 and 30°C | Zea mays |
| 9.75 | - |
free isoform SSIIa, at pH 8.0 and 30°C | Zea mays |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ADP-alpha-D-glucose + glycogen | - |
Zea mays | ADP + ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| ? | x * 180000, isoform SSIII, calculated from amino acid sequence | Zea mays |
| ? | x * 70000, isoform SSI, calculated from amino acid sequence | Zea mays |
| ? | x * 77000, isoform SSIIa, calculated from amino acid sequence | Zea mays |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| SSI | isoform | Zea mays |
| SSIIa | isoform | Zea mays |
| SSIII | isoform | Zea mays |
| starch synthase | - |
Zea mays |
Temperature Stability [°C]
| Temperature Stability Minimum [°C] | Temperature Stability Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 37 | 50 | pre-incubation at up to 45°C has no effect on the activity of isoform SSI. Isoform SSIIa is stimulated by preincubation at 37-45°C, while isoform SSIII activity is reduced by ca. 50% after brief incubation at 45°C. Isoform SSIII is stable during preincubation at 37°C. At 50°C all enzymes completely lose activity within 40 min | Zea mays |
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