Miller Laura Aaron, Baumgart Laura E, Chew Geoffrey H, deLong Mitchell A, Galloway Lamar C, Jung Kyung Woon, Merkler Kathleen A, Nagle Advait S, Poore Derek D, Yoon Cheol Hwan, Merkler David J
Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
Arch Biochem Biophys. 2003 Apr 1;412(1):3-12. doi: 10.1016/s0003-9861(02)00730-0.
The C-terminal alpha-amide moiety of most peptide hormones arises by the posttranslational cleavage of a glycine-extended precursor in a reaction catalyzed by bifunctional peptidylglycine alpha-amidating monooxygenase (PAM). Glutathione and the S-alkylated glutathiones have a C-terminal glycine and are, thus, potential substrates for PAM. The addition of PAM to glutathione, a series of S-alkylated glutathiones, and leukotriene C(4) results in the consumption of O(2) and the production of the corresponding amidated peptide and glyoxylate. This reaction proceeds in two steps with the intermediate formation of a C-terminal alpha-hydroxyglycine-extended peptide. Amidated glutathione (gammaGlu-Cys-amide) is a relatively poor substrate for glutathione S-transferase with a V/K value that is 1.3% of that for glutathione. Peptide substrates containing a penultimate hydrophobic or sulfur-containing amino acid exhibit the highest (V/K)(app) values for PAM-catalyzed amidation. The S-alkylated glutathiones incorporate both features in the penultimate position with S-decylglutathione having the highest (V/K)(app) of the substrates described in this report.
