Literature summary for 2.4.1.18 extracted from

Hamada, S.; Ito, H.; Ueno, H.; Takeda, Y.; Matsui, H.
The N-terminal region of the starch-branching enzyme from Phaseolus vulgaris L. is essential for optimal catalysis and structural stability (2007), Phytochemistry, 68, 1367-1375.

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Activating Compound

Activating Compound	Comment	Organism	Structure
citrate	in the presence of 0.1 M citrate, the activity of the active enzyme increases	Phaseolus vulgaris

Cloned(Commentary)

Cloned (Comment)	Organism
expressed in Escherichia coli BL21 (DE3)	Phaseolus vulgaris

Protein Variants

Protein Variants	Comment	Organism
D15A	D15A-PvSBE2 enzyme shows 13.1% of the specific activity of the wild type enzyme. The large decrease in the specific activities of the mutant is predominatly attributed to the reduced Vmax value.	Phaseolus vulgaris
D15E	D15E-PvSBE2 enzyme shows 31.3% of the specific activity of the wild type enzyme. The large decrease in the specific activities of the mutant is predominatly attributed to the reduced Vmax value.	Phaseolus vulgaris
H24A	H24A-PvSBE2 enzyme shows 38.3% of the specific activity of the wild type enzyme. The large decrease in the specific activities of the mutant is predominatly attributed to the reduced Vmax value.	Phaseolus vulgaris
additional information	chimeric enzymes of PvSBE2: only one chimeric recombinant protein ((I Na/2Nb)-II) has enzyme activity. It shows 6.1% of the specific activity of the wild type enzyme.	Phaseolus vulgaris
additional information	N-termial truncated enzyme of PvSBE2. Delta46-PvSBE2 has no branching enzyme activity.	Phaseolus vulgaris
R28A	R28A-PvSBE2 enzyme shows 10.7% of the specific activity of the wild type enzyme. The large decrease in the specific activities of the mutant is predominatly attributed to the reduced Vmax value.	Phaseolus vulgaris
R28K	R28K-PvSBE2 enzyme shows 93.5% of the specific activity of the wild type enzyme.	Phaseolus vulgaris

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
additional information	-	additional information	Km value of the chimeric enzyme (1Na/2Nb)-II is 0.63 mg/ml. The Km value of D15A-PvSBE2 is 1.3 mg/ml, 1.52 mg/ml for D15E-PvSBE2, 1.57 mg/ml for R28A-PvSBE2, 1.55 mg/ml for R28K-PvSBE2 and 1.59 mg/ml for H24A-PvSBE2.	Phaseolus vulgaris

Organism

Organism	UniProt	Comment	Textmining
Phaseolus vulgaris	-	-	-

Purification (Commentary)

Purification (Comment)	Organism
chimeric and N-terminal truncated enzymes: DEAE-Sepharose Cl6B column, Bio-Gel P-200 and Gigapite column all at 4°C and pH 7.5. Site-directed mutant enzymes: chelating Sepharose FF column and DEAE-Sepharose CL-6B column, all at 4°C.	Phaseolus vulgaris

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg]	Specific Activity Maximum [µmol/min/mg]	Comment	Organism
additional information	-	the chimeric (1Na/2Nb)II enzyme has a specific activity of 13 U/mg in the presence of 0.1 M citrate or 6.1 U/mg in the absence of citrate. The iodine-staining assay is performed by monitoring the decrease in absorbance at 660 nm for amylose, one unit of enzyme activity is defined as the amount of enzyme yielding a decrease in A660 of 0.1 per minute at 30°C.	Phaseolus vulgaris

Synonyms

Synonyms	Comment	Organism
SBE	starch-branching enzyme	Phaseolus vulgaris

Temperature Stability [°C]

Temperature Stability Minimum [°C]	Temperature Stability Maximum [°C]	Comment	Organism
additional information	-	when the enzymes are maintained for 15 min at various temperatures ranging from 30°C to 60°C, more than 80% of the original activity was retained up to 47.5°C for PvSBE2, up to 40°C for D15A- and D15E-PvSBE2, up to 42.5°C for R28A- and H24A-PvSBE2, and up to 45°C for R28K-PvSBE2.	Phaseolus vulgaris

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Release 2023.1 (January 2023)