Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen

1. 1. Under normal incubation conditions pellet and deaminase Euglena gracilis preparations, are able to form two different polypyrrole intermediates called P and D, respectively, which did not behave as substrates but as intermediates in the reaction, and significantly inhibited total porphyrins fo...

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Autores principales: Rossetti, María Victoria, Batlle, Alcira María del Carmen
Publicado: 1977
Materias:
porphyrin
euglena gracilis
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0020711X_v8_n11_p781_Rossetti
http://hdl.handle.net/20.500.12110/paper_0020711X_v8_n11_p781_Rossetti
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_0020711X_v8_n11_p781_Rossetti
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spelling paper:paper_0020711X_v8_n11_p781_Rossetti2023-06-08T14:41:15Z Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen Rossetti, María Victoria Batlle, Alcira María del Carmen porphyrin euglena gracilis 1. 1. Under normal incubation conditions pellet and deaminase Euglena gracilis preparations, are able to form two different polypyrrole intermediates called P and D, respectively, which did not behave as substrates but as intermediates in the reaction, and significantly inhibited total porphyrins formation. It was postulated that these supematants should contain a high percentage of larger polypyrroles that compete very unefficiently for its binding site with the intermediates bound to the enzyme. This hypothesis was supported by the data obtained when different amounts of free P and D polypyrroles were added to the enzymes; as expected, increasing amounts of free intermediates increasingly inhibited total porphyrinogens formation and had also an effect on isomer composition. With the pellet enzymes, the percentage of type I increased and correspondly decreased the amount of type III, while the reverse effect was obtained with deaminase. 2. 2. Experimental evidence indicate that the enzymic polymerization of PBG takes place in a non-stop sequence on the enzyme surface; so, the possible intermediates should remain bound to the enzyme until the growing polypyrrole chain reaches its critical length and it is ready for cyclization. The interaction, with the enzymes, of the natural polypyrroles P and D formed by pellet and deaminase Euglena gracilis without liberating them from their enzymes was then studied. As expected, incubation of enzyme-bound P intermediate with pellet or deaminase and PBG, did not inhibit total porphyrins formation but enhanced it. Incubation of D intermediate with deaminase and PBG also enhanced urogen I formation although some inhibition was obtained at the highest concentrations used. D intermediate significantly inhibited porphyrins synthesis by pellet. 3. 3. Therefore, results obtained studying the interaction of free and enzyme-bound intermediates with the enzymes involved in PBG polymerization suggest: (a) that the structure of the polypyrrole formed by the pellet is that corresponding to an isomerized tetrapyrrylmethane (PAAPAPAP), and that of the polypyrrole formed by deaminase corresponds to a nonisomerized tetrapyrrylmethane (PAPAPAPA); (b) that the intermediates must be bound to the enzyme because when they are added to the enzymic systems in its natural enzyme-polypyrrole association, they behaved as normal intermediates, enhancing total porphyrinogen formation. © 1977. Fil:Rossetti, M.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:del C. Batlle, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1977 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0020711X_v8_n11_p781_Rossetti http://hdl.handle.net/20.500.12110/paper_0020711X_v8_n11_p781_Rossetti
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic porphyrin
euglena gracilis
spellingShingle porphyrin
euglena gracilis
Rossetti, María Victoria
Batlle, Alcira María del Carmen
Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
topic_facet porphyrin
euglena gracilis
description 1. 1. Under normal incubation conditions pellet and deaminase Euglena gracilis preparations, are able to form two different polypyrrole intermediates called P and D, respectively, which did not behave as substrates but as intermediates in the reaction, and significantly inhibited total porphyrins formation. It was postulated that these supematants should contain a high percentage of larger polypyrroles that compete very unefficiently for its binding site with the intermediates bound to the enzyme. This hypothesis was supported by the data obtained when different amounts of free P and D polypyrroles were added to the enzymes; as expected, increasing amounts of free intermediates increasingly inhibited total porphyrinogens formation and had also an effect on isomer composition. With the pellet enzymes, the percentage of type I increased and correspondly decreased the amount of type III, while the reverse effect was obtained with deaminase. 2. 2. Experimental evidence indicate that the enzymic polymerization of PBG takes place in a non-stop sequence on the enzyme surface; so, the possible intermediates should remain bound to the enzyme until the growing polypyrrole chain reaches its critical length and it is ready for cyclization. The interaction, with the enzymes, of the natural polypyrroles P and D formed by pellet and deaminase Euglena gracilis without liberating them from their enzymes was then studied. As expected, incubation of enzyme-bound P intermediate with pellet or deaminase and PBG, did not inhibit total porphyrins formation but enhanced it. Incubation of D intermediate with deaminase and PBG also enhanced urogen I formation although some inhibition was obtained at the highest concentrations used. D intermediate significantly inhibited porphyrins synthesis by pellet. 3. 3. Therefore, results obtained studying the interaction of free and enzyme-bound intermediates with the enzymes involved in PBG polymerization suggest: (a) that the structure of the polypyrrole formed by the pellet is that corresponding to an isomerized tetrapyrrylmethane (PAAPAPAP), and that of the polypyrrole formed by deaminase corresponds to a nonisomerized tetrapyrrylmethane (PAPAPAPA); (b) that the intermediates must be bound to the enzyme because when they are added to the enzymic systems in its natural enzyme-polypyrrole association, they behaved as normal intermediates, enhancing total porphyrinogen formation. © 1977.
author Rossetti, María Victoria
Batlle, Alcira María del Carmen
author_facet Rossetti, María Victoria
Batlle, Alcira María del Carmen
author_sort Rossetti, María Victoria
title Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
title_short Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
title_full Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
title_fullStr Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
title_full_unstemmed Porphyrin biosynthesis in Euglena gracilis-II. Pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
title_sort porphyrin biosynthesis in euglena gracilis-ii. pyrrylmethane intermediates in the enzymic cyclotetramerization of porphobilinogen
publishDate 1977
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0020711X_v8_n11_p781_Rossetti
http://hdl.handle.net/20.500.12110/paper_0020711X_v8_n11_p781_Rossetti
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AT batllealciramariadelcarmen porphyrinbiosynthesisineuglenagracilisiipyrrylmethaneintermediatesintheenzymiccyclotetramerizationofporphobilinogen
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