Dataset Information

Stereospecific Synthesis of the Saccharosamine-Rhamnose-Fucose Fragment Present in Saccharomicin B.

ABSTRACT: A synthetic route has been developed for constructing the d-saccharosamine-l-rhamnose-d-fucose (Sac-Rha-Fuc) trisaccharide fragment present in the antibacterial natural product saccharomicin B. The Sac monosaccharide was synthesized through a modified nine step procedure starting from d-rhamnal in 23% overall yield. 1- O-TBS Sac donors were used to construct the ?-linked Sac-Rha disaccharide. This disaccharide was coupled to a Fuc acceptor under BSP/Tf2O conditions to afford a trisaccharide properly functionalized for elaboration to saccharomicin B.

SUBMITTER: Bylsma M

PROVIDER: S-EPMC6094934 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Stereospecific Synthesis of the Saccharosamine-Rhamnose-Fucose Fragment Present in Saccharomicin B.

Bylsma Marissa M Bennett Clay S CS

Organic letters 20180717 15

A synthetic route has been developed for constructing the d-saccharosamine-l-rhamnose-d-fucose (Sac-Rha-Fuc) trisaccharide fragment present in the antibacterial natural product saccharomicin B. The Sac monosaccharide was synthesized through a modified nine step procedure starting from d-rhamnal in 23% overall yield. 1- O-TBS Sac donors were used to construct the β-linked Sac-Rha disaccharide. This disaccharide was coupled to a Fuc acceptor under BSP/Tf<sub>2</sub>O conditions to afford a trisacc ...[more]

PMID: 30015496

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Project description:1. An alkaline pH change occurred when L-rhamnose, L-mannose or L-lyxose was added to L-rhamnose-grown energy-depleted suspensions of strains of Escherichia coli. This is diagnostic of sugar-H+ symport activity. 2. L-Rhamnose, L-mannose and L-lyxose were inducers of the sugar-H+ symport and of L-[14C]rhamnose transport activity. L-Rhamnose also induced the biochemically and genetically distinct L-fucose-H+ symport activity in strains competent for L-rhamnose metabolism. 3. Steady-state kinetic measurements showed that L-mannose and L-lyxose were competitive inhibitors (alternative substrates) for the L-rhamnose transport system, and that L-galactose and D-arabinose were competitive inhibitors (alternative substrates) for the L-fucose transport system. Additional measurements with other sugars of related structure defined the different substrate specificities of the two transport systems. 4. The relative rates of H+ symport and of sugar metabolism, and the relative values of their kinetic parameters, suggested that the physiological role of the transport activity was primarily for utilization of L-rhamnose, not for L-mannose or L-lyxose. 5. L-Rhamnose transport into subcellular vesicles of E. coli was dependent on respiration, was optimal at pH 7, and was inhibited by protonophores and ionophores. It was insensitive to N-ethylmaleimide or cytochalasin B. 6. L-Rhamnose, L-mannose and L-lyxose each elicited an alkaline pH change when added to energy-depleted suspensions of L-rhamnose-grown Salmonella typhimurium LT2, Klebsiella pneumoniae, Klebsiella aerogenes, Erwinia carotovora carotovora and Erwinia carotovora atroseptica. The relative rates of subsequent acidification varied, depending on both the organism and the sugar. L-Fucose promoted an alkaline pH change in all the L-rhamnose-induced organisms except the Erwinia species. No L-rhamnose-H+ symport occurred in any organism grown on L-fucose. 7. All these results showed that L-rhamnose transport into the micro-organisms occurred by a system different from that for L-fucose transport. Both systems are energized by the trans-membrane electrochemical gradient of protons. 8. Neither steady-state kinetic measurements nor binding-protein assays revealed the existence of a second L-rhamnose transport system in E. coli.

Dataset Information

Stereospecific Synthesis of the Saccharosamine-Rhamnose-Fucose Fragment Present in Saccharomicin B.

Publications

Stereospecific Synthesis of the Saccharosamine-Rhamnose-Fucose Fragment Present in Saccharomicin B.

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