Estimation of zinc pheophytins, chlorophylls, and pheophytins in mixtures in diethyl ether or 80% acetone by spectrophotometry and fluorometry

Jones, Ivan D.; White, Raymond C.; Gibbs, Eleanor; Butler, Lillian S.

doi:10.1021/jf60209a025

Cited by 20 publications

(20 citation statements)

References 5 publications

(13 reference statements)

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“…The pigments were extracted using 80% acetone following the procedure of Jones et al (1977). Amber-colored volumetric flasks were used during extraction and dilution steps.…”

Section: Methodsmentioning

confidence: 99%

Thermal Degradation Kinetics of Chlorophyll in Pureed Coriander Leaves

Rudra

Sarkar

Shivhare

2007

Food Bioprocess Technol

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Coriander leaves are widely used in cooking throughout the world. Thermal degradation kinetics of chlorophyll a, b, and total chlorophyll in coriander leaf puree was investigated at varying levels of pH (4.5-8.5) and processing temperature (80-145°C). Coriander puree at pH 4.5 was processed at 80°to 100°C, whereas that at pH 5.5 to 8.5 was processed at 105°to 145°C. Chlorophyll degradation followed first-order reaction kinetics. Good agreement was found between estimated and experimental chlorophyll retention in all cases (R 2 >0.80). Activation energies ranged from 6.57 to 96.00 kJ/mol. Reaction rate and activation energy data indicated that chlorophylls were more stable at alkaline pH. Transition state theory was applied to estimate the enthalpy, entropy, and Gibbs free energy of activation. Enthalpy of activation (ΔH # ) ranged from 3.46 to 91.99 kJ/mol, whereas entropy of activation (ΔS # ) ranged from −0.265 to −0.047 kJ/(mol K). The overall free energy change was 107.55 kJ/mol. Results indicated that, the compensation effect did not exist for chlorophyll degradation in coriander puree during thermal processing.

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“…The pigments were extracted using 80% acetone following the procedure of Jones et al (1977). Amber-colored volumetric flasks were used during extraction and dilution steps.…”

Section: Methodsmentioning

confidence: 99%

Thermal Degradation Kinetics of Chlorophyll in Pureed Coriander Leaves

Rudra

Sarkar

Shivhare

2007

Food Bioprocess Technol

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“…For quantitation, peak areas of the elution traces for each pigment at the wavelength of its absorption maximum were integrated, and relative pigment ratios were determined from the peak areas. Extinction coefficients for the solvent mixtures used were determined with pure pigments, using those in well investigated organic solvents as standards [23, 25, 26]. To verify these extinction coefficients, HPLC runs were done with pigment mixtures prepared so that their compositions were close to those of the mixtures encountered in the extracts.…”

Section: Methodsmentioning

confidence: 99%

Modification of pigment composition in the isolated reaction center of photosystem II

Gall¹,

Zehetner²,

Scherz³

et al. 1998

FEBS Letters

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The pigment content of isolated reaction centers of photosystem II was modified using an exchange protocol similar to that used for purple bacterial reaction centers. With this method, which is based on incubation of reaction centers at elevated temperature with an excess of chemically modified pigments, it was possible to incorporate [3-acetyl]-chlorophyll a and [Zn]-chlorophyll a into photosystem II reaction centers. Pigment exchange has been verified by absorption, circular dichroism and fluorescence spectroscopy, and quantitated by HPLC analysis of pigment extracts.z 1998 Federation of European Biochemical Societies.

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“…(32). Chl or Zn-phe synthesized during the in vitro reactions was determined by extraction of the pigments into 75% acetone.…”

Section: Methodsmentioning

confidence: 99%

Stabilization of Chlorophyll a-binding Apoproteins P700, CP47, CP43, D2, and D1 by Chlorophyll a or Zn-pheophytin a

Eichacker

Helfrich

Rüdiger

et al. 1996

Journal of Biological Chemistry

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Stabilization of chlorophyll a-binding apoproteins P700, CP47, CP43, D2, and D1 against proteolytic degradation has been investigated through in vitro synthesis of chlorophyll a or Zn-pheophytin a in intact etioplasts from barley. Stabilization of the apoproteins was dependent on the concentration of chlorophyll a or Znpheophytin a. Zn-pheophytin a was superior to chlorophyll a with respect to the concentration of pigment required for an equal yield of the stabilized chlorophyll a protein CP47, CP43, and P700 and for the total yield of chlorophyll a proteins. Zn-pheophytin a was most efficient for stabilizing CP47 and, at an increased concentration, efficient for stabilizing CP43, P700, and D1. Stabilization of apoproteins was highest after de novo synthesis of 90 -300 pmol of Zn-pheophytin a or of about 400 -600 pmol of chlorophyll a/4.2 ؋ 10 7 etioplasts. The yield of stabilized chlorophyll proteins decreased at higher concentrations of Zn-pheophytin a, but was unaffected by higher concentrations of chlorophyll a.The biogenesis of higher plant photosystems I and II requires assembly of nuclear-and plastid-encoded apoproteins with cofactors (e.g. chlorophyll, carotenoid, heme, quinone, iron, and manganese) within the inner plastid membrane system. Chlorophyll a (Chl) 1 is the key chromophore for higher plants to carry out the photosynthetic light reactions and is known to regulate the accumulation of the nuclear-and plastid-encoded apoproteins of the photosystems (1-4).Etioplasts isolated from 4-day-old, dark-grown barley are ideal to study the Chl-dependent accumulation of plastid-encoded photosystem proteins. Etioplasts in barley are formed from proplastids, during early primary leaf and plastid development, which proceeds uninhibited in the absence of light (5, 6).In the dark, etioplasts do not synthesize Chl and neither accumulate plastid-encoded Chl a-binding proteins (Chl aP) (7, 8) nor nuclear-encoded Chl a/b-binding apoproteins (1, 2), although they accumulate protochlorophyllide (Pchlide), a Chl precursor. When plants are illuminated, Pchlide is reduced to chlorophyllide (Chlide) in the plastid by protochlorophyllide oxidoreductase (9) in a light-and NADPH-dependent reaction. Illumination leads to disintegration of the prolamellar body and its dispersal into the primary lamellar layers of the prothylakoid membrane (10). Chlide is esterified with geranylgeranylpyrophosphate (GGPP) to yield Chl GG in a lightindependent enzymatic step catalyzed by chlorophyll synthase (11-13). In addition to the prenylation of the natural substrates Chlide a and b, chlorophyll synthase prenylates modified tetrapyrrol derivatives (14). Pentacoordinate metals (e.g. magnesium or zinc) are accepted as central atoms of the tetrapyrrole substrate, whereas metal-free pheophorbides or typical tetracoordinate central atoms (e.g. copper, nickel) do not act as a substrate for the enzyme (15). In isolated plastids Chl formation is accompanied by the accumulation of the plastid-encoded Chl-binding apoproteins (8) and assembly of the...

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Estimation of zinc pheophytins, chlorophylls, and pheophytins in mixtures in diethyl ether or 80% acetone by spectrophotometry and fluorometry

Cited by 20 publications

References 5 publications

Thermal Degradation Kinetics of Chlorophyll in Pureed Coriander Leaves

Thermal Degradation Kinetics of Chlorophyll in Pureed Coriander Leaves

Modification of pigment composition in the isolated reaction center of photosystem II

Stabilization of Chlorophyll a-binding Apoproteins P700, CP47, CP43, D2, and D1 by Chlorophyll a or Zn-pheophytin a

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