Binding parameters and thermodynamics of the interaction of imino sugars with a recombinant human acid alpha-glucosidase (alglucosidase alfa): insight into the complex formation mechanism.
BACKGROUND
Recently, enzyme enhancement therapy (EET) for Pompe disease involving imino sugars, which act as potential inhibitors of acid alpha-glucosidases in vitro, to improve the stability and/or transportation of mutant acid alpha-glucosidases in cells was studied and attracted interest. However, the mechanism underlying the molecular interaction between the imino sugars and the enzyme has not been clarified yet.


METHODS
We examined the inhibitory and binding effects of four imino sugars on a recombinant human acid alpha-glucosidase, alglucosidase alfa, by means of inhibition assaying and isothermal titration calorimetry (ITC). Furthermore, we built structural models of complexes of the catalytic domain of the enzyme with the imino sugars bound to its active site by homology modeling, and examined the molecular interaction between them.


RESULTS
All of the imino sugars examined exhibited a competitive inhibitory action against the enzyme, 1-deoxynojirimycin (DNJ) exhibiting the strongest action among them. ITC revealed that one compound molecule binds to one enzyme molecule and that DNJ most strongly binds to the enzyme among them. Structural analysis revealed that the active site of the enzyme is almost completely occupied by DNJ.


CONCLUSIONS
These biochemical and structural analyses increased our understanding of the molecular interaction between a human acid alpha-glucosidase and imino sugars.
Yoshimizu
Michiru
M
Department of Clinical Genetics, The Tokyo Metropolitan Institute of Medical Science, Tokyo Metropolitan Organization for Medical Research, Tokyo, Japan.
Tajima
Youichi
Y
Matsuzawa
Fumiko
F
Aikawa
Sei-Ichi
S
Iwamoto
Kunihiko
K
Kobayashi
Toshihide
T
Edmunds
Tim
T
Fujishima
Kaori
K
Tsuji
Daisuke
D
Itoh
Kohji
K
Ikekita
Masahiko
M
Kawashima
Ikuo
I
Sugawara
Kanako
K
Ohyanagi
Naho
N
Suzuki
Toshihiro
T
Togawa
Tadayasu
T
Ohno
Kazuki
K
Sakuraba
Hitoshi
H
D017485:1-Deoxynojirimycin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D020134:Catalytic Domain; D004347:Drug Interactions; D006009:Glycogen Storage Disease Type II / Q000201:enzymology*; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D050111:Imino Sugars / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D008958:Models, Molecular; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D013816:Thermodynamics; D000520:alpha-Glucosidases / Q000378:metabolism*
D065089:Glycoside Hydrolase Inhibitors; D050111:Imino Sugars; D011994:Recombinant Proteins; D017485:1-Deoxynojirimycin; D000520:alpha-Glucosidases