Testicular Angiotensin-converting enzyme with different glycan modification: characterization on glycosylphosphatidylinositol-anchored protein releasing and dipeptidase activities

J Biochem. 2009 Jan;145(1):115-21. doi: 10.1093/jb/mvn148. Epub 2008 Nov 4.


We have previously found that the angiotensin-converting enzyme (ACE) carries GPI-anchored protein releasing activity (GPIase) as well as dipeptidase activity. Testicular ACE (tACE), the male germinal specific isozyme, plays a crucial role in male fertilization. The amino-terminal region of this isozyme is different from that of somatic isozyme (sACE) and contains potential O-linked glycosylation sites. By multiple mutagenesis after an in silico prediction, amino acid residues acquiring O-glycans were assigned. Both GPIase and dipeptidase activities were compared between O-glycan null mutant and wild-type molecules, but no differences were found. Furthermore, the wild-type tACE was produced in two different cells (COS7 and CHO) and its activities compared. The GPIase activity, but not dipeptidase, was apparently higher for CHO-derived molecule than COS7. Sensitivity to neuraminidase and O-glycosidase digestions and the profile of glycosylation were quite different between these two molecules. Moreover, serial digestions with neuraminidase and O-glycosidase have no influence on GPIase activity of both molecules, suggesting that the sialylation and the presence of O-glycan has no influence on tACE enzyme activities, while the set of glycans modulate GPIase activity.

MeSH terms

  • Animals
  • CHO Cells
  • COS Cells
  • Chlorocebus aethiops
  • Cricetinae
  • Cricetulus
  • Dipeptidases / metabolism*
  • Glycosylphosphatidylinositols / metabolism*
  • Male
  • Mice
  • Models, Genetic
  • Mutation
  • Peptidyl-Dipeptidase A / chemistry*
  • Peptidyl-Dipeptidase A / genetics
  • Peptidyl-Dipeptidase A / metabolism
  • Recombinant Proteins
  • Testis / enzymology*
  • Testis / metabolism
  • Transfection


  • Glycosylphosphatidylinositols
  • Recombinant Proteins
  • Dipeptidases
  • dipeptidase
  • Peptidyl-Dipeptidase A