title: Substrate and inhibitor specificity of glutamine cyclotransferase (QC).
abstract: This paper reports a systematic study of the substrate and inhibitor specificity of papaya latex glutamine cyclotransferase (QC). The results showed that the second amino acid residue in N-terminal glutaminyl peptides significantly accelerated papaya latex QC-catalyzed reactions while the third residue provided no further rate enhancement. Substrate binding was shown to be the main specificity-determining step. Fifteen proline derivatives and dipeptides containing an N-terminal proline were tested and found to inhibit papaya latex QC. This supports our previous molecular modeling study of the QC catalytic pathway which suggested a structure of the reaction intermediates similar to that of L-proline.
authors.affiliation: Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg 39406-5043, USA.
authors.forename: M Y
authors.initials: MY
authors.lastname: Gololobov
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: R C
authors.initials: RC
authors.lastname: Bateman
mesh_terms: D000217:Acyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D019881:Aminoacyltransferases; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D010902:Pituitary Gland / Q000201:enzymology; D010944:Plants / Q000201:enzymology; D011392:Proline / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity
chemical_list: D011392:Proline; D000217:Acyltransferases; D019881:Aminoacyltransferases; C059280:glutaminyl-peptide cyclotransferase