Synthesis and evaluation of potential inhibitors of chondroitin AC lyase from Flavobacterium heparinum.
Chondroitin AC lyase from Flavobacterium heparinum degrades chondroitin sulfate glycosaminoglycans via an elimination mechanism, resulting in disaccharides or oligosaccharides with Delta4,5-unsaturated uronic acid residues at their nonreducing end. The syntheses and testing of two potential inhibitors of this lyase are described. Methyl O-(2-acetamido-2-deoxy-beta-D-galactopyranosyl)-(1-->4)-alpha-L-threo-hex-4-enopyranoside, 1, has the trigonal geometry at C5 of the uronic acid moiety expected at the transition state, yet retains the "leaving group" sugar moiety. Surprisingly, compound 1 showed no inhibition of the enzyme. The novel 5-nitro sugar, phenyl (5S)-5-nitro-beta-D-xylopyranoside, 2, is a monosaccharide nitro analogue of the natural substrate, with C5 being a carbon acid of pK(a) 8.8. The rate of reprotonation of the anion generated at this center is sufficiently low that the anion of 2 can be used directly in initial steady-state velocity measurements without significant interference from the conjugate carbon acid. The anion of compound 2 was found to be a competitive inhibitor with a K(i) value of 5 mM, whereas the conjugate acid had a K(i) value of 35 mM.
Rye
Carl S
CS
Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada, V6T 1Z1.
Withers
Stephen G
SG
D002384:Catalysis; D002808:Chondroitin Lyases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D002809:Chondroitin Sulfates / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D005417:Flavobacterium / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011134:Polysaccharides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism; D013997:Time Factors; D014574:Uronic Acids / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism
D004187:Disaccharides; D011134:Polysaccharides; D014574:Uronic Acids; C038142:chondroitin sulfate glycosaminoglycan; C469654:methyl O-(2-acetamido-2-deoxy-beta-D-galactopyranosyl)-(1-4)-alpha-L-threo-hex- 4-enopyranoside; D002809:Chondroitin Sulfates; D002808:Chondroitin Lyases