Hydrolytic activity of alpha-galactosidases against deoxy derivatives of p-nitrophenyl alpha-D-galactopyranoside.
The four possible monodeoxy derivatives of p-nitrophenyl (PNP) alpha-D-galactopyranoside were synthesized, and hydrolytic activities of the alpha-galactosidase of green coffee bean, Mortierella vinacea and Aspergillus niger against them were elucidated. The 2- and 6-deoxy substrates were hydrolyzed by the enzymes from green coffee bean and M. vinacea, while they scarcely acted on the 3- and 4-deoxy compounds. On the other hand, A. niger alpha-galactosidase hydrolyzed only the 2-deoxy compound in these deoxy substrates, and the activity was very high. These results indicate that the presence of two hydroxyl groups (OH-3 and -4) is essential for the compounds to act as substrates for the enzymes of green coffee bean and M. vinacea, while the three hydroxyl groups (OH-3, -4, and -6) are necessary for the activity of the A. niger enzyme. The kinetic parameters (K(m) and Vmax) of the enzymes for the hydrolysis of PNP alpha-D-galactopyranoside and its deoxy derivatives were obtained from kinetic studies.
Hakamata
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Laboratory of Bio-organic Chemistry, College of Bioresource Sciences, Nihon University, Tokyo, Japan.
Nishio
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T
Oku
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D001234:Aspergillus niger / Q000201:enzymology; D002384:Catalysis; D003069:Coffee / Q000201:enzymology; D005656:Fungal Proteins / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009598:Nitrophenylgalactosides / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D013379:Substrate Specificity; D000519:alpha-Galactosidase / Q000378:metabolism*
D003069:Coffee; D005656:Fungal Proteins; D010940:Plant Proteins; D009598:Nitrophenylgalactosides; C059200:4-nitrophenylgalactoside; D000519:alpha-Galactosidase