Abstract
Two types of alpha-glucan phosphorylase [EC 2.4.1.1] from spinach leaves have been separately purified to near homogeneity. Type I enzyme shows a subunit molecular weight of 92,000 and Km values for amylopectin, glycogen and amylose much smaller than that for maltopentose. Cyclodextrin is a normal competitive inhibitor with respect to maltopentose, while it is a multi-site competitive type inhibitor with respect to amylopectin, glycogen or amylose. Type II enzyme shows a subunit molecular weight of 108,000, and utilizes amylopectin, amylose and maltopentose well, but glycogen very poorly. On affinity electrophoresis, Type II enzyme shows no affinity for glycogen and the dissociation constant for amylopectin is more than a thousand-fold greater than that of Type I enzyme. Type II enzyme has similar characteristics (subunit size, glucan specificity, and mode of cyclodextrin inhibition) to potato phosphorylase, for which cyclodextrin is a normal competitive inhibitor with respect to either maltopentose or amylopectin. Enzyme-glucan binding models have been proposed to explain these different kinetic properties. In spinach Type I phosphorylase, multiple glucan binding sites are located on the same face of the enzyme molecule to enable a single large substrate to be bound by riding on all the site; in spinach Type II and potato phosphorylases, two glucan binding sites are three-dimensionally arranged in a manner that excludes the possibility of the binding of amylopectin by riding on the two sites.
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Claims 15
Claim · model-written summary
Spinach Type I phosphorylase has a subunit molecular weight of 92,000.
- Taxon
- spinach
Spinacia oleraceae0 - Gene
- Type I enzymee1
- Outcome
- subunit molecular weighte1
- Value
- 92,000e1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e1“Type I enzyme shows a subunit molecular weight of 92,000”
Claim · model-written summary
For spinach Type I phosphorylase, Km values for amylopectin, glycogen and amylose are much smaller than the Km for maltopentose.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type I enzymee1
- Compound
- amylopectin, glycogen and amylosee2
- Outcome
- Km values for amylopectin, glycogen and amylosee2
- Direction
- much smallere2
- Comparator
- maltopentosee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e1“Type I enzyme shows a subunit molecular weight of 92,000”
e2“Km values for amylopectin, glycogen and amylose much smaller than that for maltopentose”
Claim · model-written summary
Cyclodextrin is a normal competitive inhibitor of spinach phosphorylase with respect to maltopentose.
- Taxon
- spinachSpinacia oleraceae0
- Compound
- Cyclodextrine3
- Outcome
- normal competitive inhibitore3
- Comparator
- maltopentosee3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e3“Cyclodextrin is a normal competitive inhibitor with respect to maltopentose, while it is a multi-site competitive type inhibitor with respect to amylopectin, glycogen or amylose”
Claim · model-written summary
Cyclodextrin is a multi-site competitive type inhibitor of spinach phosphorylase with respect to amylopectin, glycogen or amylose.
- Taxon
- spinachSpinacia oleraceae0
- Compound
- Cyclodextrine3
- Outcome
- multi-site competitive type inhibitore3
- Comparator
- amylopectin, glycogen or amylosee3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e3“Cyclodextrin is a normal competitive inhibitor with respect to maltopentose, while it is a multi-site competitive type inhibitor with respect to amylopectin, glycogen or amylose”
Claim · model-written summary
Spinach Type II phosphorylase has a subunit molecular weight of 108,000.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type II enzymee5
- Outcome
- subunit molecular weighte5
- Value
- 108,000e5
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e5“Type II enzyme shows a subunit molecular weight of 108,000”
Claim · model-written summary
Spinach Type II phosphorylase utilizes amylopectin, amylose and maltopentose well.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type II enzymee6
- Outcome
- utilizes amylopectin, amylose and maltopentosee6
- Direction
- welle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e6“Type II enzyme shows a subunit molecular weight of 108,000, and utilizes amylopectin, amylose and maltopentose well”
Claim · model-written summary
Spinach Type II phosphorylase utilizes glycogen very poorly.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type II enzymee6
- Outcome
- glycogene7
- Direction
- very poorlye7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e6“Type II enzyme shows a subunit molecular weight of 108,000, and utilizes amylopectin, amylose and maltopentose well”
e7“utilizes amylopectin, amylose and maltopentose well, but glycogen very poorly”
Claim · model-written summary
Spinach Type II phosphorylase shows no affinity for glycogen on affinity electrophoresis.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type II enzymee1
- Compound
- glycogene1
- Outcome
- affinity for glycogene1
- Qualifier
- On affinity electrophoresise1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e1“On affinity electrophoresis, Type II enzyme shows no affinity for glycogen”
Claim · model-written summary
For spinach Type II phosphorylase, the dissociation constant for amylopectin is more than a thousand-fold greater than that of Type I.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type II enzymee1
- Compound
- amylopectine1
- Outcome
- dissociation constant for amylopectine1
- Direction
- greatere1
- Value
- more than a thousand-folde1
- Comparator
- Type I enzymee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e1“Type II enzyme shows no affinity for glycogen and the dissociation constant for amylopectin is more than a thousand-fold greater than that of Type I enzyme”
Claim · model-written summary
Spinach Type II phosphorylase has subunit size, glucan specificity and mode of cyclodextrin inhibition similar to potato phosphorylase.
- Taxon
- spinachSpinacia oleraceae0
- Gene
- Type II enzymee1
- Outcome
- subunit size, glucan specificity, and mode of cyclodextrin inhibitione1
- Direction
- similare1
- Comparator
- potato phosphorylasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e1“Type II enzyme has similar characteristics (subunit size, glucan specificity, and mode of cyclodextrin inhibition) to potato phosphorylase”
Claim · model-written summary
In potato phosphorylase, cyclodextrin is a normal competitive inhibitor with respect to maltopentose or amylopectin.
- Taxon
- potato
Solanum tuberosume1 - Compound
- cyclodextrine2
- Outcome
- normal competitive inhibitore2
- Comparator
- maltopentose or amylopectine2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Type II enzyme has similar characteristics (subunit size, glucan specificity, and mode of cyclodextrin inhibition) to potato phosphorylase”
e2“for which cyclodextrin is a normal competitive inhibitor with respect to either maltopentose or amylopectin”
Claim · model-written summary
Enzyme-glucan binding models have been proposed to explain the different kinetic properties of the spinach phosphorylase types.
- Taxon
- spinachSpinacia oleraceae0
- Outcome
- different kinetic propertiese1
- Qualifier
- Enzyme-glucan binding modelse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“from spinach leaves”
e1“Enzyme-glucan binding models have been proposed to explain these different kinetic properties”
Claim · model-written summary
In spinach Type I phosphorylase, multiple glucan binding sites on the same face of the enzyme let one large substrate bind by riding on all the sites.
- Taxon
- spinachSpinacia oleraceae1
- Gene
- Type I phosphorylasee1
- Outcome
- a single large substrate to be bounde1
- Qualifier
- multiple glucan binding sites are located on the same face of the enzyme moleculee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“In spinach Type I phosphorylase, multiple glucan binding sites are located on the same face of the enzyme molecule to enable a single large substrate to be bound by riding on all the site”
Claim · model-written summary
In spinach Type II phosphorylase, two glucan binding sites are arranged so that amylopectin cannot bind by riding on both sites.
- Taxon
- spinachSpinacia oleraceae1
- Outcome
- the binding of amylopectin by riding on the two sitese1
- Qualifier
- two glucan binding sites are three-dimensionally arranged in a manner that excludes the possibilitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“in spinach Type II and potato phosphorylases, two glucan binding sites are three-dimensionally arranged in a manner that excludes the possibility of the binding of amylopectin by riding on the two sites”
Claim · model-written summary
In potato phosphorylase, two glucan binding sites are arranged so that amylopectin cannot bind by riding on both sites.
- Taxon
- potatoSolanum tuberosume1
- Outcome
- the binding of amylopectin by riding on the two sitese1
- Qualifier
- two glucan binding sites are three-dimensionally arranged in a manner that excludes the possibilitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“in spinach Type II and potato phosphorylases, two glucan binding sites are three-dimensionally arranged in a manner that excludes the possibility of the binding of amylopectin by riding on the two sites”