The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform
Hitoshi Tamiaki - One of the best experts on this subject based on the ideXlab platform.
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bcic catalyzed c132 Demethoxycarbonylation of metal pheophorbide a alkyl esters
ChemBioChem, 2020Co-Authors: Mitsuaki Hirose, Misato Teramura, Jiro Harada, Hitoshi TamiakiAbstract:Bacteriochlorophyll c molecules self-aggregate to form large oligomers in the core part of chlorosomes, which are the main light-harvesting antenna systems of green photosynthetic bacteria. In the biosynthetic pathway of bacteriochlorophyll c, a BciC enzyme catalyzes the removal of the C132 -methoxycarbonyl group of chlorophyllide a, which possesses a free propionate residue at the C17-position and a magnesium ion as the central metal. The in vitro C132 -Demethoxycarbonylations of chlorophyll a derivatives with various alkyl propionate residues and central metals were examined by using the BciC enzyme derived from one green sulfur bacteria species, Chlorobaculum tepidum. The BciC enzymatic reactions of zinc pheophorbide a alkyl esters were gradually suppressed with an increase of the alkyl chain length in the C17-propionate residue (from methyl to pentyl esters) and finally the hexyl ester became inactive for the BciC reaction. Although not only the zinc but also nickel and copper complexes were demethoxycarbonylated by the BciC enzyme, the reactions were largely dependent on the coordination ability of the central metals: Zn>Ni>Cu. The above substrate specificity indicates that the BciC enzyme would not bind directly to the carboxy group of chlorophyllide a, but would bind to its central magnesium to form the stereospecific complex of BciC with chlorophyllide a, giving pyrochlorophyllide a, which lacks the (132 R)-methoxycarbonyl group.
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In vitro Demethoxycarbonylation of various chlorophyll analogs by a BciC enzyme
Photosynthesis Research, 2019Co-Authors: Misato Teramura, Jiro Harada, Hitoshi TamiakiAbstract:Unique light-harvesting antennas in the green sulfur bacterium Chlorobaculum tepidum , called chlorosomes, consist of self-aggregates of bacteriochlorophyll (BChl) c . In the biosynthesis of BChl c , BciC demethoxycarbonylase removes the C13^2-methoxycarbonyl group to facilitate the self-aggregation of BChl c . We previously reported the in vitro BciC-enzymatic reactions and discussed the function of this enzyme in the biosynthesis of BChl c . This study aims to examine the substrate specificity of BciC in detail using several semi-synthetic (bacterio)chlorophyll derivatives. The results indicate that the substrate specificity of BciC is measurably affected by structural changes on the A/B rings including the bacteriochlorin π-systems. Moreover, BciC showed its activity on a Zn-chelated chlorophyll derivative. On the contrary, BciC recognized structural modifications on the D/E rings, including porphyrin pigments, which resulted in the significant decrease in the enzymatic activity. The utilization of BciC provides mild conditions that may be useful for the in vitro preparation of various chemically (un)stable chlorophyllous pigments.
Kiyoharu Nishide - One of the best experts on this subject based on the ideXlab platform.
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lipase catalyzed asymmetric Demethoxycarbonylation formal syntheses of carbacyclin ajmalicine and tetrahydroalstonine
Tetrahedron-asymmetry, 1998Co-Authors: Manabu Node, T Inoue, Mamoru Araki, Daisaku Nakamura, Kiyoharu NishideAbstract:Abstract Both enantiomers of C 2 -symmetric dimethyl 3,7-dihydroxybicyclo[3.3.0]-octa-2,6-diene-2,6-dicarboxylate 3 were prepared in enantiomerically pure form from symmetric tetraester 1 by the lipase-catalyzed Demethoxycarbonylation, respectively. Double asymmetric differentiation with lipase in the above Demethoxycarbonylation was observed. Their applications to formal total syntheses of (+)-carbacyclin and (−)-ajmalicine including (−)-tetrahydroalstonine are also described.
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an asymmetric synthesis of c2 symmetric dimethyl 3 7 dioxo cis bicyclo 3 3 0 octane 2 6 dicarboxylate by lipase catalyzed Demethoxycarbonylation
Tetrahedron Letters, 1995Co-Authors: Manabu Node, T Inoue, Mamoru Araki, Daisaku Nakamura, Kiyoharu NishideAbstract:Both enantiomers of C2-symmetric dimethyl 3,7-dioxo-cis-bicyclo[3.3.0]-octane-2,6-dicarboxylate (3) were prepared in enantiomerically pure form by the lipase-catalyzed Demethoxycarbonylation, respectively. An expeditious formal total synthesis of (+)-carbacyclin using this hybrid process was done.
Manabu Node - One of the best experts on this subject based on the ideXlab platform.
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lipase catalyzed asymmetric Demethoxycarbonylation formal syntheses of carbacyclin ajmalicine and tetrahydroalstonine
Tetrahedron-asymmetry, 1998Co-Authors: Manabu Node, T Inoue, Mamoru Araki, Daisaku Nakamura, Kiyoharu NishideAbstract:Abstract Both enantiomers of C 2 -symmetric dimethyl 3,7-dihydroxybicyclo[3.3.0]-octa-2,6-diene-2,6-dicarboxylate 3 were prepared in enantiomerically pure form from symmetric tetraester 1 by the lipase-catalyzed Demethoxycarbonylation, respectively. Double asymmetric differentiation with lipase in the above Demethoxycarbonylation was observed. Their applications to formal total syntheses of (+)-carbacyclin and (−)-ajmalicine including (−)-tetrahydroalstonine are also described.
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an asymmetric synthesis of c2 symmetric dimethyl 3 7 dioxo cis bicyclo 3 3 0 octane 2 6 dicarboxylate by lipase catalyzed Demethoxycarbonylation
Tetrahedron Letters, 1995Co-Authors: Manabu Node, T Inoue, Mamoru Araki, Daisaku Nakamura, Kiyoharu NishideAbstract:Both enantiomers of C2-symmetric dimethyl 3,7-dioxo-cis-bicyclo[3.3.0]-octane-2,6-dicarboxylate (3) were prepared in enantiomerically pure form by the lipase-catalyzed Demethoxycarbonylation, respectively. An expeditious formal total synthesis of (+)-carbacyclin using this hybrid process was done.
Misato Teramura - One of the best experts on this subject based on the ideXlab platform.
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bcic catalyzed c132 Demethoxycarbonylation of metal pheophorbide a alkyl esters
ChemBioChem, 2020Co-Authors: Mitsuaki Hirose, Misato Teramura, Jiro Harada, Hitoshi TamiakiAbstract:Bacteriochlorophyll c molecules self-aggregate to form large oligomers in the core part of chlorosomes, which are the main light-harvesting antenna systems of green photosynthetic bacteria. In the biosynthetic pathway of bacteriochlorophyll c, a BciC enzyme catalyzes the removal of the C132 -methoxycarbonyl group of chlorophyllide a, which possesses a free propionate residue at the C17-position and a magnesium ion as the central metal. The in vitro C132 -Demethoxycarbonylations of chlorophyll a derivatives with various alkyl propionate residues and central metals were examined by using the BciC enzyme derived from one green sulfur bacteria species, Chlorobaculum tepidum. The BciC enzymatic reactions of zinc pheophorbide a alkyl esters were gradually suppressed with an increase of the alkyl chain length in the C17-propionate residue (from methyl to pentyl esters) and finally the hexyl ester became inactive for the BciC reaction. Although not only the zinc but also nickel and copper complexes were demethoxycarbonylated by the BciC enzyme, the reactions were largely dependent on the coordination ability of the central metals: Zn>Ni>Cu. The above substrate specificity indicates that the BciC enzyme would not bind directly to the carboxy group of chlorophyllide a, but would bind to its central magnesium to form the stereospecific complex of BciC with chlorophyllide a, giving pyrochlorophyllide a, which lacks the (132 R)-methoxycarbonyl group.
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In vitro Demethoxycarbonylation of various chlorophyll analogs by a BciC enzyme
Photosynthesis Research, 2019Co-Authors: Misato Teramura, Jiro Harada, Hitoshi TamiakiAbstract:Unique light-harvesting antennas in the green sulfur bacterium Chlorobaculum tepidum , called chlorosomes, consist of self-aggregates of bacteriochlorophyll (BChl) c . In the biosynthesis of BChl c , BciC demethoxycarbonylase removes the C13^2-methoxycarbonyl group to facilitate the self-aggregation of BChl c . We previously reported the in vitro BciC-enzymatic reactions and discussed the function of this enzyme in the biosynthesis of BChl c . This study aims to examine the substrate specificity of BciC in detail using several semi-synthetic (bacterio)chlorophyll derivatives. The results indicate that the substrate specificity of BciC is measurably affected by structural changes on the A/B rings including the bacteriochlorin π-systems. Moreover, BciC showed its activity on a Zn-chelated chlorophyll derivative. On the contrary, BciC recognized structural modifications on the D/E rings, including porphyrin pigments, which resulted in the significant decrease in the enzymatic activity. The utilization of BciC provides mild conditions that may be useful for the in vitro preparation of various chemically (un)stable chlorophyllous pigments.
Jiro Harada - One of the best experts on this subject based on the ideXlab platform.
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bcic catalyzed c132 Demethoxycarbonylation of metal pheophorbide a alkyl esters
ChemBioChem, 2020Co-Authors: Mitsuaki Hirose, Misato Teramura, Jiro Harada, Hitoshi TamiakiAbstract:Bacteriochlorophyll c molecules self-aggregate to form large oligomers in the core part of chlorosomes, which are the main light-harvesting antenna systems of green photosynthetic bacteria. In the biosynthetic pathway of bacteriochlorophyll c, a BciC enzyme catalyzes the removal of the C132 -methoxycarbonyl group of chlorophyllide a, which possesses a free propionate residue at the C17-position and a magnesium ion as the central metal. The in vitro C132 -Demethoxycarbonylations of chlorophyll a derivatives with various alkyl propionate residues and central metals were examined by using the BciC enzyme derived from one green sulfur bacteria species, Chlorobaculum tepidum. The BciC enzymatic reactions of zinc pheophorbide a alkyl esters were gradually suppressed with an increase of the alkyl chain length in the C17-propionate residue (from methyl to pentyl esters) and finally the hexyl ester became inactive for the BciC reaction. Although not only the zinc but also nickel and copper complexes were demethoxycarbonylated by the BciC enzyme, the reactions were largely dependent on the coordination ability of the central metals: Zn>Ni>Cu. The above substrate specificity indicates that the BciC enzyme would not bind directly to the carboxy group of chlorophyllide a, but would bind to its central magnesium to form the stereospecific complex of BciC with chlorophyllide a, giving pyrochlorophyllide a, which lacks the (132 R)-methoxycarbonyl group.
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In vitro Demethoxycarbonylation of various chlorophyll analogs by a BciC enzyme
Photosynthesis Research, 2019Co-Authors: Misato Teramura, Jiro Harada, Hitoshi TamiakiAbstract:Unique light-harvesting antennas in the green sulfur bacterium Chlorobaculum tepidum , called chlorosomes, consist of self-aggregates of bacteriochlorophyll (BChl) c . In the biosynthesis of BChl c , BciC demethoxycarbonylase removes the C13^2-methoxycarbonyl group to facilitate the self-aggregation of BChl c . We previously reported the in vitro BciC-enzymatic reactions and discussed the function of this enzyme in the biosynthesis of BChl c . This study aims to examine the substrate specificity of BciC in detail using several semi-synthetic (bacterio)chlorophyll derivatives. The results indicate that the substrate specificity of BciC is measurably affected by structural changes on the A/B rings including the bacteriochlorin π-systems. Moreover, BciC showed its activity on a Zn-chelated chlorophyll derivative. On the contrary, BciC recognized structural modifications on the D/E rings, including porphyrin pigments, which resulted in the significant decrease in the enzymatic activity. The utilization of BciC provides mild conditions that may be useful for the in vitro preparation of various chemically (un)stable chlorophyllous pigments.