Flexibility of the coordination geometry around the cupric ions in Cu(II)-rat dipeptidyl peptidase III is important for the expression of enzyme activity.
Dipeptidyl peptidase III (DPP III), the zinc peptidase, has a unique helix portion in the metal-binding motif (HELLGH). The enzyme activity of the cupric derivative of rat DPP III (Cu(II)-rat DPP III) for Lys-Ala-β-NA is about 30% of that of the wild-type enzyme. On the other hand, the enzyme activity of Cu(II)-rat del-DPP III, in which Leu453 is deleted from the metal-binding motif, possesses only 1-2% of the enzyme activity of rat del-DPP III. The EPR spectra of Cu(II)-rat DPP III in the presence of various concentrations of the substrate, Lys-Ala-β-NA, changed dramatically, showing formation of the enzyme-metal-substrate complex. The EPR spectra of Cu(II)-rat del-DPP III did not change in the presence of excess Lys-Ala-β-NA. The deletion of Leu453 from the HELLGH motif of rat DPP III leads to a complete loss of flexibility in the ligand geometry around the cupric ions. Under the formation of the enzyme-metal-substrate complex, Glu451 of Cu(II)-rat DPP III is sufficiently able to approach the water molecule via a very different orientation from that of the resting state; however, Glu451 of Cu(II)-rat del-DPP III is not able to access the water molecule.
Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Gakuen-cho, Fukuyama 729-0292, Japan. hirose@fubac.fukuyama-u.ac.jp
Junzo
J
Hirose
Toshiyuki
T
Hata
Chie
C
Kawaoka
Tomohiro
T
Ikeura
Suguru
S
Kitahara
Kozue
K
Horii
Hisao
H
Tomida
Hiroyuki
H
Iwamoto
Yukio
Y
Ono
Kayoko M
KM
Fukasawa
D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D003300:Copper; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D051381:Rats; D017384:Sequence Deletion
C013112:4-methoxy-2-naphthylamine; D003300:Copper; D015081:2-Naphthylamine; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C100152:dipeptidyl peptidase III