TY - JOUR
T1 - Peptidyl-glycine α-amidating monooxygenase is present in islet secretory granules of the anglerfish, Lophius americanus
AU - Mackin, Robert B.
AU - Flacker, Jonathan M.
AU - Mackin, Julie A.
AU - Noe, Bryan D.
N1 - Funding Information:
i This research was supported by National Institutes of Health Grant AM-26378 and National Science Foundation Grant DCB-8700843. * Portions of this work were presented in abstract form at the 68th Annual Meeting of The Endocrine Society, Anaheim, CA, June, 1986. 3 To whom correspondence should be addressed. 4 Abbreviations used: PAM, peptidyl-glycine a-amidating monooxygenase; aPY, anglerfish peptide Y; aGLP-II, anglerfish glucagon-like peptide II; Tes, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid; ass-28, anglerlish somatostatin-28.
PY - 1987/8
Y1 - 1987/8
N2 - Anglerfish islet secretory granules have been examined for the presence of an enzyme which could perform C-terminal amidation of glucagon-like peptide II and possibly anglerfish peptide Y. Using [125I]d-Tyr-Val-Gly as substrate, a peptidyl-glycine α-amidating monooxygenase (PAM) was detected in islet secretory granule lysates. The enzyme is active between pH 6.0 and 8.5 and exhibits maximal activity near pH 7.0. The islet PAM requires Cu2+, ascorbate, and molecular oxygen for activity. Other divalent metal ions and redox cofactors were tested and found to be inactive in the assay. Even though added Cu2+ and ascorbate are required for detecting islet PAM activity, when these factors were incubated with substrate in the absence of secretory granule lysate, no activity was observed. It was also found that the addition of higher than optimal concentrations of either Cu2+ or ascorbate inhibited amidating activity. The results demonstrate that a PAM is present in secretory granules of anglerfish islet tissue. The characteristics of the islet PAM are similar to those of PAMs identified and characterized in other tissues which produce bioactive C-terminally amidated peptides.
AB - Anglerfish islet secretory granules have been examined for the presence of an enzyme which could perform C-terminal amidation of glucagon-like peptide II and possibly anglerfish peptide Y. Using [125I]d-Tyr-Val-Gly as substrate, a peptidyl-glycine α-amidating monooxygenase (PAM) was detected in islet secretory granule lysates. The enzyme is active between pH 6.0 and 8.5 and exhibits maximal activity near pH 7.0. The islet PAM requires Cu2+, ascorbate, and molecular oxygen for activity. Other divalent metal ions and redox cofactors were tested and found to be inactive in the assay. Even though added Cu2+ and ascorbate are required for detecting islet PAM activity, when these factors were incubated with substrate in the absence of secretory granule lysate, no activity was observed. It was also found that the addition of higher than optimal concentrations of either Cu2+ or ascorbate inhibited amidating activity. The results demonstrate that a PAM is present in secretory granules of anglerfish islet tissue. The characteristics of the islet PAM are similar to those of PAMs identified and characterized in other tissues which produce bioactive C-terminally amidated peptides.
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U2 - 10.1016/0016-6480(87)90156-0
DO - 10.1016/0016-6480(87)90156-0
M3 - Article
C2 - 3305155
AN - SCOPUS:0023388709
SN - 0016-6480
VL - 67
SP - 263
EP - 269
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
IS - 2
ER -