TY - JOUR
T1 - Kinetic evaluation of β-neoendorphin hydrolysis by the somatic and testicular isozymes of human angiotensin-converting enzyme
AU - Hayakari, Makoto
AU - Satoh, Kimihiko
AU - Ookawa, Keizou
AU - Kano, Hiroko
AU - Murakami, Satoshi
AU - Ikeda, Noriaki
AU - Tsuchida, Shigeki
N1 - Funding Information:
We are grateful to Mr. Kaoru Kojima and Dr. Ikunoshin Kato, Research Institute for Glycotechnology, Hirosaki 036, Japan, for the measurement of tandem mass–mass spectra of peptides. This work was supported in part by a grant from the Karoji Memorial Fund for Medical Research at Hirosaki University School of Medicine.
PY - 1997/4/25
Y1 - 1997/4/25
N2 - Angiotensin-converting enzyme (ACE) has both somatic and testicular isozymes, the former possessing two catalytically active domains, amino-terminal and carboxyl-terminal, while the latter has only the carboxyl-terminal one. We compared hydrolysis processes of the nonapeptide β-neoendorphin by the two isozymes of human ACE. Both isozymes hydrolyzed the peptide to Tyr1-Gly2-Gly3 by the sequential removal of carboxyl-terminal dipeptides in three consecutive steps. The rate constant values for the second step, conversion of β-neoendorphin1-7 to Leu-enkephalin, by the somatic isozyme in the presence of 10 or 200 mM NaCl were 4-fold higher than those for the first step, conversion of β-neoendorphin1-9 to β-neoendorphin1-7. The k(cat) values of the somatic isozyme for β-neoendorphin1-7 were 2-fold higher than those for β-neoendorphin1-9, indicating that β-neoendorphin1-7 is more rapidly hydrolyzed than β-neoendorphin1-9. The rate constant value for the second step at 10 mM NaCl was 5-fold higher than that for the testicular isozyme. Similar extent of difference was also observed in k(cat) values for β-neoendorphin1-7 between the two isozymes. These results suggest that the amino-terminal domain of the somatic isozyme mainly contributes to the conversion of β-neoendorphin1-7 to Leu-enkephalin at a low NaCl concentration. Optimal chloride concentrations for the individual steps of β-neoendorphin1-9 hydrolysis differed between the two isozymes.
AB - Angiotensin-converting enzyme (ACE) has both somatic and testicular isozymes, the former possessing two catalytically active domains, amino-terminal and carboxyl-terminal, while the latter has only the carboxyl-terminal one. We compared hydrolysis processes of the nonapeptide β-neoendorphin by the two isozymes of human ACE. Both isozymes hydrolyzed the peptide to Tyr1-Gly2-Gly3 by the sequential removal of carboxyl-terminal dipeptides in three consecutive steps. The rate constant values for the second step, conversion of β-neoendorphin1-7 to Leu-enkephalin, by the somatic isozyme in the presence of 10 or 200 mM NaCl were 4-fold higher than those for the first step, conversion of β-neoendorphin1-9 to β-neoendorphin1-7. The k(cat) values of the somatic isozyme for β-neoendorphin1-7 were 2-fold higher than those for β-neoendorphin1-9, indicating that β-neoendorphin1-7 is more rapidly hydrolyzed than β-neoendorphin1-9. The rate constant value for the second step at 10 mM NaCl was 5-fold higher than that for the testicular isozyme. Similar extent of difference was also observed in k(cat) values for β-neoendorphin1-7 between the two isozymes. These results suggest that the amino-terminal domain of the somatic isozyme mainly contributes to the conversion of β-neoendorphin1-7 to Leu-enkephalin at a low NaCl concentration. Optimal chloride concentrations for the individual steps of β-neoendorphin1-9 hydrolysis differed between the two isozymes.
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U2 - 10.1016/S0167-4838(96)00205-1
DO - 10.1016/S0167-4838(96)00205-1
M3 - Article
C2 - 9165097
AN - SCOPUS:0030948520
SN - 0167-4838
VL - 1339
SP - 31
EP - 38
JO - Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
JF - Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
IS - 1
ER -