Specificity of GlcNAc-PI de-N-acetylase of GPI biosynthesis and synthesis of parasite-specific suicide substrate inhibitors.
The substrate specificities of Trypanosoma brucei and human (HeLa) GlcNAc-PI de-N-acetylases were determined using 24 substrate analogues. The results show the following. (i) The de-N-acetylases show little specificity for the lipid moiety of GlcNAc-PI. (ii) The 3'-OH group of the GlcNAc residue is essential for substrate recognition whereas the 6'-OH group is dispensable and the 4'-OH, while not required for recognition, cannot be epimerized or substituted. (iii) The parasite enzyme can act on analogues containing betaGlcNAc or aromatic N-acyl groups, whereas the human enzyme cannot. (iv) Three GlcNR-PI analogues are de-N-acetylase inhibitors, one of which is a suicide inhibitor. (v) The suicide inhibitor most likely forms a carbamate or thiocarbamate ester to an active site hydroxy-amino acid or Cys or residue such that inhibition is reversed by certain nucleophiles. These and previous results were used to design two potent (IC50 = 8 nM) parasite-specific suicide substrate inhibitors. These are potential lead compounds for the development of anti-protozoan parasite drugs.
Smith
T K
TK
Division of Biological Chemistry & Molecular Microbiology, The School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
Crossman
A
A
Borissow
C N
CN
Paterson
M J
MJ
Dix
A
A
Brimacombe
J S
JS
Ferguson
M A
MA
D000085:Acetates / Q000378:metabolism; D000107:Acetylation; D000117:Acetylglucosamine / Q000031:analogs & derivatives / Q000737:chemistry; D000581:Amidohydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008968:Molecular Conformation; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
D000085:Acetates; D004791:Enzyme Inhibitors; D017261:Glycosylphosphatidylinositols; D000581:Amidohydrolases; C087696:N-acetylglucosaminyl-phosphatidylinositol de-N-acetylase; D000117:Acetylglucosamine