My. Gololobov et al., SUBSTRATE AND INHIBITOR SPECIFICITY OF GLUTAMINE CYCLOTRANSFERASE (QC), Biological chemistry Hoppe-Seyler, 377(6), 1996, pp. 395-398
This paper reports a systematic study of the substrate and inhibitor s
pecificity of papaya latex glutamine cyclotransferase (QC). The result
s showed that the second amino acid residue in N-terminal glutaminyl p
eptides significantly accelerated papaya latex QC-catalyzed reactions
while the third residue provided no further rate enhancement. Substrat
e binding was shown to be the main specificity-determining step. Fifte
en proline derivatives and dipeptides containing an N-terminal proline
were tested and found to inhibit papaya latex QC. This supports our p
revious molecular modeling study of the QC catalytic pathway which sug
gested a structure of the reaction intermediates similar to that of L-
proline.