MS/MS fragmentation-guided search of TMG-chitooligomycins and their structure-activity relationship in specific β-N-acetylglucosaminidase inhibition

Org Biomol Chem. 2011 Apr 21;9(8):2943-51. doi: 10.1039/c0ob01090a. Epub 2011 Mar 4.

Abstract

The reducing tetrasaccharide TMG-chitotriomycin (1) is an inhibitor of β-N-acetylglucosaminidase (GlcNAcase), produced by the actinomycete Streptomyces anulatus NBRC13369. The inhibitor shows a unique inhibitory spectrum, that is, selectivity toward enzymes from chitin-containing organisms such as insects and fungi. Nevertheless, its structure-selectivity relationship remains to be clarified. In this study, we conducted a structure-guided search of analogues of 1 in order to obtain diverse N,N,N-trimethylglucosaminium (TMG)-containing chitooligosaccharides. In this approach, the specific fragmentation profile of 1 on ESI-MS/MS analysis was used for the selective detection of desired compounds. As a result, two new analogues, named TMG-chitomonomycin (3) and TMG-chitobiomycin (2), were obtained from a culture filtrate of 1-producing Streptomyces. Their enzyme-inhibiting activity revealed that the potency and selectivity depended on the degree of polymerization of the reducing end GlcNAc units. Furthermore, a computational modeling study inspired the inhibitory mechanism of TMG-related compounds as a mimic of the substrate in the Michaelis complex of the GH20 enzyme. This study is an example of the successful application of a MS/MS experiment for structure-guided isolation of natural products.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylglucosaminidase / antagonists & inhibitors*
  • Acetylglucosaminidase / chemistry
  • Aspergillus oryzae / drug effects
  • Aspergillus oryzae / enzymology
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / pharmacology
  • Glucosamine / analogs & derivatives*
  • Glucosamine / chemistry
  • Models, Molecular
  • Molecular Structure
  • Oligomycins / chemistry*
  • Protein Structure, Tertiary
  • Spectrometry, Mass, Electrospray Ionization
  • Streptomyces coelicolor / drug effects
  • Streptomyces coelicolor / enzymology
  • Structure-Activity Relationship
  • Tandem Mass Spectrometry

Substances

  • Enzyme Inhibitors
  • N,N,N-trimethylglucosaminium
  • Oligomycins
  • Acetylglucosaminidase
  • Glucosamine