A novel acid phosphatase from Aspergillus niger KU-8 that specifically hydrolyzes C-6 phosphate groups of phosphoryl oligosaccharides.
We had analyzed the detailed structures of the phosphoryl oligosaccharide-1 (PO-1) fraction that was the main component of phosphoryl oligosaccharides (POs) prepared from a potato starch hydrolysate. PO-1 fraction was made up of 3-phosphoryl oligosaccharides and 6-phosphoryl oligosaccharides. Aspergillus niger strain KU-8 produced two types of intracellular acid phosphatase (EC 3.1.3.2, ACPase); ACPase I and II. ACPase II preferentially dephosphorylated 6-phosphoryl oligosaccharides rather than 3-phosphoryl oligosaccharides. The molecular weight of the enzyme was estimated as 66 kDa by SDS-polyacrylamide gel electrophoresis and about 260 kDa by gel filtration, implying the active form to be a tetramer. The optimum pH and temperature of the enzyme were 2.0-2.5 and 60 degrees C, respectively. ACPase II was stable below 50 degrees C for 30 min and pH 2.0-10.0 for 60 min. In spite of the strict specificity toward 6-phosphoryl oligosaccharides in the PO-1 fraction, ACPase II was able to hydrolyze Fru-1,6-di-P, ATP, pyrophosphate, and polyphosphate as well as pNPP and Glc-6-P, a broad substrate specificity.
To-o
K
K
Biochemical Research Laboratory, Ezaki Glico Co., Ltd., Osaka, Japan.
Kamasaka
H
H
Kusaka
K
K
Kuriki
T
T
Kometani
T
T
Okada
S
S
D000135:Acid Phosphatase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D001234:Aspergillus niger / Q000201:enzymology*; D002474:Cell-Free System; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D005656:Fungal Proteins / Q000032:analysis / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D013213:Starch / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
D003470:Culture Media; D005656:Fungal Proteins; D009844:Oligosaccharides; D010710:Phosphates; D013213:Starch; D000135:Acid Phosphatase