Degradation of chlorophyll a to pheophytin a, pheophorbide a, and pyrroporphine XV for tracer studies

Wickliff, James L.; Aronoff, S.

doi:10.1016/0003-2697(63)90006-x

Cited by 19 publications

(12 citation statements)

References 3 publications

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“…As reported by Perkins and Roberts (6), this procedure degraded "4C-pheophytin a extensively into 14C-pheophorbide a and two slow moving red fluorescent radioactive products (Fig. 3A), one of which is probably 14C-pyropheophorbide a (6,16). The radiochromatogram tracing of this fraction chromatographed on Silica Gel H is given in Figure 3A.…”

supporting

confidence: 61%

“…Vol. 47,1971 Upon conversion into "4C-pheophytin a and rechromatography on cellulose MN 300, the specific radioactivity remained unchanged indicating that after the cellulose purification step, the 'IC-chlorophyll a was free of significant "4C-porphyrin, phorbin, or colorless radioactive contaminants (5,6,16). Figure 2A represents a radiochromatogram tracing of "4C-chlorophyll a purified to constant specific radioactivity as described above.…”

mentioning

confidence: 97%

“…When the homogenates prepared from 2.5-hr irradiated cotyledons (green homogenate) or etiolated cotyledons (etiolated homogenate) were incubated with 14C-ALA for 16 hr at 28 C in the presence and absence of light, the "C-Mg protoporphyrin monoester, "4C-protochlorophyllide and "4C-protochlorophyllide ester pools became radioactive (Table I). In both cases the ratios of "4C-protochlorophyllide ester to "4C-protochlorophyllide were 2-to 3-fold higher when the incubations were carried out in the light than in the dark (Table I).…”

mentioning

confidence: 99%

“…DISCUSSION Isolated chlorophylls are notoriously contaminated by colorless lipids (5,6,14). These substances interfere with the nuclear magnetic and infrared spectra of chlorophylls (14) and above all with the purification of 14C-chlorophylls to constant specific radioactivity (6,16). This is especially true when '4C-chlorophylls are prepared from nonspecific tetrapyrrole precursors such as 2-14C-acetate, 2, 3-14C-succinate or 14C02; these substrates are then incorporated into the contaminating colorless substances as well (6,16).…”

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confidence: 99%

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Chlorophyll Biosynthesis in a Cell-free System from Higher Plants

Rebeiz

Castelfranco

1971

Plant Physiol.

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A crude homogenate obtained from greening cucumber (Cucumis sativus, L.) cotyledons in tris-sucrose, pH 7.7, containing coenzyme A, glutathione, potassium phosphate, pH 7.7, methyl alcohol, magnesium, nicotinamide adenine dinucleotide, and adenosine triphosphate, is able to incorporate 4-_4C-6-aminolevulinic acid into chlorophyll a and b in the presence of oxygen. If the homogenates are prepared from etiolated cotyledons which have been exposed to light for two and one-half hours, "4C-chlorophyll a is synthesized. However, when the homogenates are prepared from cotyledons illuminated for four and one-half hours, both 14C. chlorophyll a and b are produced.Recently Rebeiz and Castelfranco (10) reported the biosynthesis of '4C-protochlorophyllide and "4C-protochlorophyllide ester from 4-14C-6-aminolevulinic acid by a cell-free system prepared from etiolated cucumber cotyledons. They were able to show that the activity is associated with etioplasts and has a pH optimum of 7.7. For the formation of '4C-protochlorophyllide ester, oxygen, GSH, methyl alchol, Mg2+, Pi , and NAD are required (10). For the formation of "4C-protochlorophyllide, CoA, ATP, and possibly K+ are needed in addition to the above cofactors (10).Previous work with etiolated cucumber cotyledons has shown that it takes 1 to 1.5 hr of exposure to white light before chlorophyll a begins to accumulate and about 3.0 hr before the appearance of chlorophyll b (7). Therefore, we have chosen to investigate the chlorophyll-biosynthetic ability of cell-free homogenates derived from three types of plant tissues: (a) etiolated cucumber cotyledons, (b) etiolated cotyledons after 2.5 hr of light treatment, (c) etiolated cotyledons after 4.5 hr of light treatment. When the cell-free homogenates derived from greening cotyledon tissues were incubated in the presence of "(C-6-aminolevulinic acid, 02, and the other cofactors needed for in vitro protochlorophyll biosynthesis (10), 14C-chlorophylls were obtained.

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supporting

confidence: 61%

mentioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Chlorophyll Biosynthesis in a Cell-free System from Higher Plants

Rebeiz

Castelfranco

1971

Plant Physiol.

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“…A part of the cell suspensIOn was drIed under vacuum and the powder was named as Chlorella powder (II). IsolatIOn of the photosensltIzmg pigments from the cell suspensIOn m aqueous ethanol was performed accordmg to the method of Tamura et al 21 wIth some modificatIOns. By centrIfugatIOn of the cell suspenSIOn, the green extract was separated from the cell residue, which was further extracted 3 times With 3 lIters each of methanol.…”

Section: Methodsmentioning

confidence: 99%

Isolation of 10-Hydroxypheophorbideaas a Photosensitizing Pigment from Alcohol-treatedChlorellaCells

Endô¹,

Hosoya²,

Koyama³

et al. 1982

Agricultural and Biological Chemistry

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New method of photosensitizer accumulation for photodynamic therapy in an experimental liver tumor

Nishiwaki

Sakaguchi

1989

Lasers Surg Med

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A new sensitizing method of photodynamic therapy for malignant tumors and its effects was studied. Prepared for the study were pheophorbide a (Phd), dissolved in an oily contrast medium, Lipiodol (LPD-Phd), and water-soluble pheophorbide a (W-S Phd) as sensitizers, and VX-2 tumor in rabbit livers. The Phd distribution was compared after intraarterial (i.a.) administration of LPD-Phd or W-S Phd and intravenous (i.v.) administration of W-S Phd. Phd was extracted with methanol at 24 h after injection, and the supernatant absorbance was measured at 670 nm by spectrophotometry. The tumor showed higher values of Phd than did the liver with LPD-Phd i.a. and W-S Phd i.a. (P less than .01). Conversely, the tumor accumulated less Phd than did the liver with W-S Phd i.v. (P less than .05). We subsequently produced severe photo-destruction in a Walker tumor in a Sprague-Dawley rat liver with slight damage to adjacent liver tissue using LPD-Phd i.a. and Nd-YAG dye laser irradiation at 670 nm. The intraarterial administration of a photosensitizer may make it possible to treat liver tumors by photodynamic therapy.

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Degradation of chlorophyll a to pheophytin a, pheophorbide a, and pyrroporphine XV for tracer studies

Cited by 19 publications

References 3 publications

Chlorophyll Biosynthesis in a Cell-free System from Higher Plants

Chlorophyll Biosynthesis in a Cell-free System from Higher Plants

Isolation of 10-Hydroxypheophorbideaas a Photosensitizing Pigment from Alcohol-treatedChlorellaCells

New method of photosensitizer accumulation for photodynamic therapy in an experimental liver tumor

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