TY - JOUR
T1 - The role of metal on imide hydrolysis
T2 - Metal content and pH profiles of metal ion-replaced mammalian imidase
AU - Huang, Cheng Yang
AU - Yang, Yuh-Shyong
PY - 2002/10/4
Y1 - 2002/10/4
N2 - Imidase catalyzes the hydrolysis of a variety of imides. The removal of metal from imidase eliminates its activity but does not affect its tetrameric and secondary structure. The reactivation of the apoenzyme with transition metal ions Co2+, Zn2+, Mn2+, and Cd2+ shows that imidase activity is linearly dependent on the amount of metal ions added. Ni2+ and Cu2+ are also inserted, one per enzyme subunit, into the apoimidase, but do not restore imidase activity. Enzyme activity with different metal replaced imidase varies significantly. However, the changes of the metal contents do not appear to affect the pKas obtained from the bell-shaped pH profiles of metal reconstituted imidase. The metal-hydroxide mechanism for imidase action is not supported based on the novel findings from this study. It is proposed that metal ion in mammalian imidase functions as a Lewis acid, which stabilizes the developing negative charge of imide substrate in transition state.
AB - Imidase catalyzes the hydrolysis of a variety of imides. The removal of metal from imidase eliminates its activity but does not affect its tetrameric and secondary structure. The reactivation of the apoenzyme with transition metal ions Co2+, Zn2+, Mn2+, and Cd2+ shows that imidase activity is linearly dependent on the amount of metal ions added. Ni2+ and Cu2+ are also inserted, one per enzyme subunit, into the apoimidase, but do not restore imidase activity. Enzyme activity with different metal replaced imidase varies significantly. However, the changes of the metal contents do not appear to affect the pKas obtained from the bell-shaped pH profiles of metal reconstituted imidase. The metal-hydroxide mechanism for imidase action is not supported based on the novel findings from this study. It is proposed that metal ion in mammalian imidase functions as a Lewis acid, which stabilizes the developing negative charge of imide substrate in transition state.
KW - Imidase
KW - Metal replacement
KW - Transition metal
KW - pH profile
UR - http://www.scopus.com/inward/record.url?scp=0036034451&partnerID=8YFLogxK
U2 - 10.1016/S0006-291X(02)02330-6
DO - 10.1016/S0006-291X(02)02330-6
M3 - Article
C2 - 12359259
AN - SCOPUS:0036034451
SN - 0006-291X
VL - 297
SP - 1027
EP - 1032
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 4
ER -