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Literature summary extracted from
- Crystal structure of the Chlamydomonas starch debranching enzyme isoamylase ISA1 reveals insights into the mechanism of branch trimming and complex assembly (2014), J. Biol. Chem., 289, 22991-23003.
Cloned(Commentary)
| EC Number | Cloned (Comment) | Organism |
|---|---|---|
| 3.2.1.68 | the STA7 locus encodes ISA1, recombinant expression of His-tagged subunit ISA1 in Escherichia coli strain BL21(DE3) | Chlamydomonas reinhardtii |
| 3.2.1.68 | the STA8 locus encodes ISA2, recombinant expression of HA-tagged ISA2 in strain BafV13 and BafO6 | Chlamydomonas reinhardtii |
Crystallization (Commentary)
| EC Number | Crystallization (Comment) | Organism |
|---|---|---|
| 3.2.1.68 | purified subunit ISA1 alone and in complex with maltoheptaose, X-ray diffraction structure determination at 2.3 A and 2.4 A, respectively | Chlamydomonas reinhardtii |
| 3.2.1.68 | purified subunit ISA1 alone and in complex with maltoheptaose, X-ray diffrcation structure determination at 2.3 A and 2.4 A, respectively. The subunit structure includes highly conserved catalytic (beta/alpha)8 A-domain (aa 184-750), N-terminal beta-sandwich domain (aa 76-183), and C-terminal beta-sandwich domain (aa 751-875) | Chlamydomonas reinhardtii |
Protein Variants
| EC Number | Protein Variants | Comment | Organism |
|---|---|---|---|
| 3.2.1.68 | additional information | functional complementation of sta8 mutant strains BafV13 and BafO6 with ISA2 or ISA2-HA, overview | Chlamydomonas reinhardtii |
Molecular Weight [Da]
| EC Number | Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|---|
| 3.2.1.68 | 93000 | - |
2 * 93000, subunit ISA1, crystal structure analysis and SDS-PAGE | Chlamydomonas reinhardtii |
| 3.2.1.68 | 180000 | - |
subunit ISA1, crystal structure analysis and SDS-PAGE | Chlamydomonas reinhardtii |
Organism
| EC Number | Organism | UniProt | Comment | Textmining |
|---|---|---|---|---|
| 3.2.1.68 | Chlamydomonas reinhardtii | A8IQR3 | - |
- |
| 3.2.1.68 | Chlamydomonas reinhardtii | Q7X8Q2 | - |
- |
| 3.2.1.68 | Chlamydomonas reinhardtii 330 | A8IQR3 | - |
- |
| 3.2.1.68 | Chlamydomonas reinhardtii 330 | Q7X8Q2 | - |
- |
Purification (Commentary)
| EC Number | Purification (Comment) | Organism |
|---|---|---|
| 3.2.1.68 | recombinant His-tagged subunit ISA1 from Escherichia coli strain BL21(DE3) by nickel affinity chromatography | Chlamydomonas reinhardtii |
Substrates and Products (Substrate)
| EC Number | Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|---|
| 3.2.1.68 | amylopectin + H2O | - |
Chlamydomonas reinhardtii | ? | - |
? |  |
| 3.2.1.68 | amylopectin + H2O | - |
Chlamydomonas reinhardtii 330 | ? | - |
? | |
| 3.2.1.68 | beta-limit dextrin + H2O | - |
Chlamydomonas reinhardtii | ? | - |
? | |
| 3.2.1.68 | beta-limit dextrin + H2O | - |
Chlamydomonas reinhardtii 330 | ? | - |
? | |
| 3.2.1.68 | glycogen + H2O | - |
Chlamydomonas reinhardtii | ? | - |
? | |
| 3.2.1.68 | glycogen + H2O | - |
Chlamydomonas reinhardtii 330 | ? | - |
? | |
| 3.2.1.68 | additional information | pullulan is a poor substrate | Chlamydomonas reinhardtii | ? | - |
? | |
| 3.2.1.68 | additional information | pullulan is a poor substrate | Chlamydomonas reinhardtii 330 | ? | - |
? | |
| 3.2.1.68 | starch + H2O | specific hydrolysis of alpha-1,6-glucosidic linkages | Chlamydomonas reinhardtii | ? | detection of aminobenzamide-labeled maltooligosaccharide products, overview | ? | |
| 3.2.1.68 | starch + H2O | specific hydrolysis of alpha-1,6-glucosidic linkages | Chlamydomonas reinhardtii 330 | ? | detection of aminobenzamide-labeled maltooligosaccharide products, overview | ? | |
Subunits
| EC Number | Subunits | Comment | Organism |
|---|---|---|---|
| 3.2.1.68 | homodimer | 2 * 93000, subunit ISA1, crystal structure analysis and SDS-PAGE | Chlamydomonas reinhardtii |
Synonyms
| EC Number | Synonyms | Comment | Organism |
|---|---|---|---|
| 3.2.1.68 | CrISA1 | - |
Chlamydomonas reinhardtii |
| 3.2.1.68 | ISA1 | - |
Chlamydomonas reinhardtii |
| 3.2.1.68 | ISA2 | - |
Chlamydomonas reinhardtii |
| 3.2.1.68 | isoamylase 1 | - |
Chlamydomonas reinhardtii |
| 3.2.1.68 | isoamylase 2 | - |
Chlamydomonas reinhardtii |
| 3.2.1.68 | starch debranching enzyme | - |
Chlamydomonas reinhardtii |
pH Optimum
| EC Number | pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|---|
| 3.2.1.68 | 7 | - |
assay at | Chlamydomonas reinhardtii |
General Information
| EC Number | General Information | Comment | Organism |
|---|---|---|---|
| 3.2.1.68 | evolution | subunit ISA1 is a family 13 glycoside hydrolase, which has activity for hydrolyzing alpha-1,6-glucosidic linkages corresponding to branch points of growing amylopectin molecules | Chlamydomonas reinhardtii |
| 3.2.1.68 | evolution | subunit ISA2 is a family 13 glycoside hydrolase, but its putative catalytic residues are altered, rendering it enzymatically inactive. Despite its inactivity, ISA2 is evolutionarily conserved in plants, and has been suggested to play a role as a regulatory subunit for ISA1 | Chlamydomonas reinhardtii |
| 3.2.1.68 | malfunction | mutants of the STA8 locus accumulate both phytoglycogen and a reduced amount of high amylose starch | Chlamydomonas reinhardtii |
| 3.2.1.68 | malfunction | mutation of the STA7 locus leads to a very severe reduction of starch content and its replacement by a water-soluble polysaccharide phytoglycogen | Chlamydomonas reinhardtii |
| 3.2.1.68 | additional information | subunit ISA2 interacts physically with ISA1, presence of both homomeric ISA1 and heteromeric ISA1-ISA2 complexes in vivo | Chlamydomonas reinhardtii |
| 3.2.1.68 | additional information | subunit ISA2 interacts physically with ISA1, presence of both homomeric ISA1 and heteromeric ISA1-ISA2 complexes in vivo. Subunit ISA1 enzyme is also partially functional without subunit ISA2 | Chlamydomonas reinhardtii |
| 3.2.1.68 | physiological function | starch debranching enzymes isoamylase 1 and 2, ISA1 and ISA2, are known to exist in a large complex and are involved in the biosynthesis and crystallization of starch. The function of the complex is to remove misplaced branches of growing amylopectin molecules, which would otherwise prevent the association and crystallization of adjacent linear chains | Chlamydomonas reinhardtii |
| 3.2.1.68 | physiological function | starch debranching enzymes isoamylase 1 and 2, ISA1 and ISA2, are known to exist in a large complex and are involved in the biosynthesis and crystallization of starch. The function of the complex is to remove misplaced branches of growing amylopectin molecules, which would otherwise prevent the association and crystallization of adjacent linear chains. ISA2 plays a role as a regulatory subunit for ISA1 | Chlamydomonas reinhardtii |
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