Gladys Nazario - Academia.edu (original) (raw)
Papers by Gladys Nazario
Plant Physiology, Dec 1, 1993
In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,... more In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) is provided by de novo purine biosynthesis: (a) [14C]glycine, [14C]bicarbonate, and [14C]formate were incorporated into inosine 5'monophosphate (IMP), sum of adenine nucleotides (ZAde), theobromine, and caffeine; and (b) incorporation of [14C]formate into IMP, ZAde, theobromine, and caffeine was inhibited by azaserine, a known inhibitor of de novo purine biosynthesis. Capacity of coffee leaves to salvage added purines was demonstrated by incorporation of [14C]hypoxanthine into ZAde and the incorporation of ["Cladenosine, [14C]adenine, ["Clinosine, and ['4C]hypoxanthine into both theobromine and caffeine. Consistent with synthesis of theobromine from two separate purine nucleotide pools, one synthesized de novo and one via salvage, added xanthine 5'-monophosphate (XMP), inosine, or hypoxanthine failed to reduce the incorporation of [14C]formate into theobromine but diluted the specific radioactivity of ["C]adenosine and [14C]adenine incorporated into theobromine. Evidence that theobromine is not the immediate precursor of caffeine is provided: (a) [14C]xanthine was incorporated into caffeine but not into theobromine; (b) exogenous xanthine diluted the specific radioactivity of caffeine synthesized from ["Cladenine and [14C]hypoxanthine but caused accumulation of radiolabel in theobromine; (c) allopurinol, a known inhibitor of the conversion of hypoxanthine to xanthine, reduced incorporation of ['%Iadenine and [14C]hypoxanthine into caffeine but caused accumulation of radiolabel in theobromine; and (d) incorporation of [14C]formate into caffeine, but not into theobromine, was reduced by added XMP, inosine, or hypoxanthine. ~~~~ ~ ~ ~ Attempts to elucidate the pathway by which theobromine (3,7-dimethylxanthine) is synthesized in Coffea arabica have been limited exclusively to studies of the metabolism of preformed nucleosides and bases or their 1-, 3-, or 7-methylated counterparts (Looser et al., 1974; Suzuki and Takahashi, 1975a; Roberts and Waller, 1979; Suzuki and Waller, 1984). The results of these studies demonstrated that radiolabeled adenine, guanine, and xanthine were incorporated into 7-methylxanthine, theobromine, and caffeine (Suzuki ~ ~ ~ ' Supported in part by a fellowship from the Graduate Division,
El problema con el complejo de Bemisia tauuci, y los virus trasmitidos por esta mosca blanca, com... more El problema con el complejo de Bemisia tauuci, y los virus trasmitidos por esta mosca blanca, comienza en Puerto Rico temprano en la decada de los 50 (1951) en el tabaco y algunas de las malvaceas (okra y ciertas ornamentales).
HortScience, 1990
A study was undertaken to identify the pathway(s) leading to the synthesis of caffeine and theobr... more A study was undertaken to identify the pathway(s) leading to the synthesis of caffeine and theobromine in leaves of Coffea arabica. The relative contribution of purine nucleosidcs and bases to the biosynthesis of these alkaloids was assessed by measuring the incorporation of radiolabeled inosine, adenosine, adenine, hypoxanthine, and xanthine into caffeine and theobromine.The results of this investigation suggest that caffeine and theobromine are end products of two distinctively different pathways. The incorporation of radiolabeled formate, adenosine, and xanthine was significantly greater into caffeine than into theobromine. Furthermore, exogenously supplied theobromine did not dilute the incorporation of [14C]formate, [14C]inosine, or [14C]xanthine into caffeine. In contrast, radiolabeled adenine was incorporated into theobromine but not into caffeine, and exogenously supplied adenine diluted the incorporation of [14 C]adenosine into theobromine, but not into caffeine.Taken toget...
Plant Physiology, 1993
In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,... more In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) is provided by de novo purine biosynthesis: (a) [14C]glycine, [14C]bicarbonate, and [14C]formate were incorporated into inosine 5'monophosphate (IMP), sum of adenine nucleotides (ZAde), theobromine, and caffeine; and (b) incorporation of [14C]formate into IMP, ZAde, theobromine, and caffeine was inhibited by azaserine, a known inhibitor of de novo purine biosynthesis. Capacity of coffee leaves to salvage added purines was demonstrated by incorporation of [14C]hypoxanthine into ZAde and the incorporation of ["Cladenosine, [14C]adenine, ["Clinosine, and ['4C]hypoxanthine into both theobromine and caffeine. Consistent with synthesis of theobromine from two separate purine nucleotide pools, one synthesized de novo and one via salvage, added xanthine 5'-monophosphate (XMP), inosine, or hypoxanthine failed to reduce the incorporation of [14C]formate into theobromine but diluted the specific radioactivity of ["C]adenosine and [14C]adenine incorporated into theobromine. Evidence that theobromine is not the immediate precursor of caffeine is provided: (a) [14C]xanthine was incorporated into caffeine but not into theobromine; (b) exogenous xanthine diluted the specific radioactivity of caffeine synthesized from ["Cladenine and [14C]hypoxanthine but caused accumulation of radiolabel in theobromine; (c) allopurinol, a known inhibitor of the conversion of hypoxanthine to xanthine, reduced incorporation of ['%Iadenine and [14C]hypoxanthine into caffeine but caused accumulation of radiolabel in theobromine; and (d) incorporation of [14C]formate into caffeine, but not into theobromine, was reduced by added XMP, inosine, or hypoxanthine. ~~~~ ~ ~ ~ Attempts to elucidate the pathway by which theobromine (3,7-dimethylxanthine) is synthesized in Coffea arabica have been limited exclusively to studies of the metabolism of preformed nucleosides and bases or their 1-, 3-, or 7-methylated counterparts (Looser et al., 1974; Suzuki and Takahashi, 1975a; Roberts and Waller, 1979; Suzuki and Waller, 1984). The results of these studies demonstrated that radiolabeled adenine, guanine, and xanthine were incorporated into 7-methylxanthine, theobromine, and caffeine (Suzuki ~ ~ ~ ' Supported in part by a fellowship from the Graduate Division,
Journal of College Science Teaching, 2008
Plant Physiology, 1993
The capacity of Coffea arabica leaves (5-x 5-mm pieces) to synthesize de novo and catabolize puri... more The capacity of Coffea arabica leaves (5-x 5-mm pieces) to synthesize de novo and catabolize purine nucleotides to provide precursors for caffeine (1,3,7-trimethylxanthine) was investigated. Consistent with de novo synthesis, glycine, bicarbonate, and formate were incorporated into the purine ring of inosine 5'-monophosphate (IMP) and adenine nucleotides (ZAde); azaserine, a known inhibitor of purine de novo synthesis, inhibited incorporation. Activity of the de novo pathway in C. arabica per g fresh weight of leaf tissue during a 3-h incubation period was 8 2 4 nmol of formate incorporated into IMP, 61 f 7 nmol into ZAde, and 150 nmol into caffeine (the latter during a 7-h incubation). Coffee leaves exhibited classical purine catabolism. Radiolabeled formate, inosine, adenosine, and adenine were incorporated into hypoxanthine and xanthine, which were catabolized to allantoin and urea. Urease activity was demonstrated. Per g fresh weight, coffee leaf squares incorporated 90 f 22 nmol of xanthine into caffeine in 7 h but degraded 102 f 1 nmol of xanthine to allantoin in 3 h. Feedback control of de novo purine biosynthesis was contrasted in C. arabica and Cucurbifa pepo, a species that does not synthesize purine alkaloids. End-product inhibition was demonstrated to occur in both species but at different enzyme reactions.
Plant Physiology, Dec 1, 1993
In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,... more In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) is provided by de novo purine biosynthesis: (a) [14C]glycine, [14C]bicarbonate, and [14C]formate were incorporated into inosine 5'monophosphate (IMP), sum of adenine nucleotides (ZAde), theobromine, and caffeine; and (b) incorporation of [14C]formate into IMP, ZAde, theobromine, and caffeine was inhibited by azaserine, a known inhibitor of de novo purine biosynthesis. Capacity of coffee leaves to salvage added purines was demonstrated by incorporation of [14C]hypoxanthine into ZAde and the incorporation of ["Cladenosine, [14C]adenine, ["Clinosine, and ['4C]hypoxanthine into both theobromine and caffeine. Consistent with synthesis of theobromine from two separate purine nucleotide pools, one synthesized de novo and one via salvage, added xanthine 5'-monophosphate (XMP), inosine, or hypoxanthine failed to reduce the incorporation of [14C]formate into theobromine but diluted the specific radioactivity of ["C]adenosine and [14C]adenine incorporated into theobromine. Evidence that theobromine is not the immediate precursor of caffeine is provided: (a) [14C]xanthine was incorporated into caffeine but not into theobromine; (b) exogenous xanthine diluted the specific radioactivity of caffeine synthesized from ["Cladenine and [14C]hypoxanthine but caused accumulation of radiolabel in theobromine; (c) allopurinol, a known inhibitor of the conversion of hypoxanthine to xanthine, reduced incorporation of ['%Iadenine and [14C]hypoxanthine into caffeine but caused accumulation of radiolabel in theobromine; and (d) incorporation of [14C]formate into caffeine, but not into theobromine, was reduced by added XMP, inosine, or hypoxanthine. ~~~~ ~ ~ ~ Attempts to elucidate the pathway by which theobromine (3,7-dimethylxanthine) is synthesized in Coffea arabica have been limited exclusively to studies of the metabolism of preformed nucleosides and bases or their 1-, 3-, or 7-methylated counterparts (Looser et al., 1974; Suzuki and Takahashi, 1975a; Roberts and Waller, 1979; Suzuki and Waller, 1984). The results of these studies demonstrated that radiolabeled adenine, guanine, and xanthine were incorporated into 7-methylxanthine, theobromine, and caffeine (Suzuki ~ ~ ~ ' Supported in part by a fellowship from the Graduate Division,
El problema con el complejo de Bemisia tauuci, y los virus trasmitidos por esta mosca blanca, com... more El problema con el complejo de Bemisia tauuci, y los virus trasmitidos por esta mosca blanca, comienza en Puerto Rico temprano en la decada de los 50 (1951) en el tabaco y algunas de las malvaceas (okra y ciertas ornamentales).
HortScience, 1990
A study was undertaken to identify the pathway(s) leading to the synthesis of caffeine and theobr... more A study was undertaken to identify the pathway(s) leading to the synthesis of caffeine and theobromine in leaves of Coffea arabica. The relative contribution of purine nucleosidcs and bases to the biosynthesis of these alkaloids was assessed by measuring the incorporation of radiolabeled inosine, adenosine, adenine, hypoxanthine, and xanthine into caffeine and theobromine.The results of this investigation suggest that caffeine and theobromine are end products of two distinctively different pathways. The incorporation of radiolabeled formate, adenosine, and xanthine was significantly greater into caffeine than into theobromine. Furthermore, exogenously supplied theobromine did not dilute the incorporation of [14C]formate, [14C]inosine, or [14C]xanthine into caffeine. In contrast, radiolabeled adenine was incorporated into theobromine but not into caffeine, and exogenously supplied adenine diluted the incorporation of [14 C]adenosine into theobromine, but not into caffeine.Taken toget...
Plant Physiology, 1993
In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,... more In Coffea arabica leaves, the purine ring of theobromine (3,7dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) is provided by de novo purine biosynthesis: (a) [14C]glycine, [14C]bicarbonate, and [14C]formate were incorporated into inosine 5'monophosphate (IMP), sum of adenine nucleotides (ZAde), theobromine, and caffeine; and (b) incorporation of [14C]formate into IMP, ZAde, theobromine, and caffeine was inhibited by azaserine, a known inhibitor of de novo purine biosynthesis. Capacity of coffee leaves to salvage added purines was demonstrated by incorporation of [14C]hypoxanthine into ZAde and the incorporation of ["Cladenosine, [14C]adenine, ["Clinosine, and ['4C]hypoxanthine into both theobromine and caffeine. Consistent with synthesis of theobromine from two separate purine nucleotide pools, one synthesized de novo and one via salvage, added xanthine 5'-monophosphate (XMP), inosine, or hypoxanthine failed to reduce the incorporation of [14C]formate into theobromine but diluted the specific radioactivity of ["C]adenosine and [14C]adenine incorporated into theobromine. Evidence that theobromine is not the immediate precursor of caffeine is provided: (a) [14C]xanthine was incorporated into caffeine but not into theobromine; (b) exogenous xanthine diluted the specific radioactivity of caffeine synthesized from ["Cladenine and [14C]hypoxanthine but caused accumulation of radiolabel in theobromine; (c) allopurinol, a known inhibitor of the conversion of hypoxanthine to xanthine, reduced incorporation of ['%Iadenine and [14C]hypoxanthine into caffeine but caused accumulation of radiolabel in theobromine; and (d) incorporation of [14C]formate into caffeine, but not into theobromine, was reduced by added XMP, inosine, or hypoxanthine. ~~~~ ~ ~ ~ Attempts to elucidate the pathway by which theobromine (3,7-dimethylxanthine) is synthesized in Coffea arabica have been limited exclusively to studies of the metabolism of preformed nucleosides and bases or their 1-, 3-, or 7-methylated counterparts (Looser et al., 1974; Suzuki and Takahashi, 1975a; Roberts and Waller, 1979; Suzuki and Waller, 1984). The results of these studies demonstrated that radiolabeled adenine, guanine, and xanthine were incorporated into 7-methylxanthine, theobromine, and caffeine (Suzuki ~ ~ ~ ' Supported in part by a fellowship from the Graduate Division,
Journal of College Science Teaching, 2008
Plant Physiology, 1993
The capacity of Coffea arabica leaves (5-x 5-mm pieces) to synthesize de novo and catabolize puri... more The capacity of Coffea arabica leaves (5-x 5-mm pieces) to synthesize de novo and catabolize purine nucleotides to provide precursors for caffeine (1,3,7-trimethylxanthine) was investigated. Consistent with de novo synthesis, glycine, bicarbonate, and formate were incorporated into the purine ring of inosine 5'-monophosphate (IMP) and adenine nucleotides (ZAde); azaserine, a known inhibitor of purine de novo synthesis, inhibited incorporation. Activity of the de novo pathway in C. arabica per g fresh weight of leaf tissue during a 3-h incubation period was 8 2 4 nmol of formate incorporated into IMP, 61 f 7 nmol into ZAde, and 150 nmol into caffeine (the latter during a 7-h incubation). Coffee leaves exhibited classical purine catabolism. Radiolabeled formate, inosine, adenosine, and adenine were incorporated into hypoxanthine and xanthine, which were catabolized to allantoin and urea. Urease activity was demonstrated. Per g fresh weight, coffee leaf squares incorporated 90 f 22 nmol of xanthine into caffeine in 7 h but degraded 102 f 1 nmol of xanthine to allantoin in 3 h. Feedback control of de novo purine biosynthesis was contrasted in C. arabica and Cucurbifa pepo, a species that does not synthesize purine alkaloids. End-product inhibition was demonstrated to occur in both species but at different enzyme reactions.