Chlorophyll-Pheophytin: Temperature Coefficient of the Rate of Pheophytin Formation

Mackinney, G.; Joslyn, M. A.

doi:10.1021/ja01854a507

Cited by 79 publications

(74 citation statements)

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“…Another difference observed with the kinetics of the acidification was that the process in DMF is much slower for Chl b than for Chl a or Pchl (Table IV). This observation is in accordance with similar studies done using acetone solutions (6,10,13,18).…”

Section: Resultssupporting

confidence: 93%

Formulae for Determination of Chlorophyllous Pigments Extracted with N,N-Dimethylformamide

Moran¹

1982

Plant Physiol.

1,239

637

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The extraction of chlorophylls in higher plant tissue using N,N-dimethylformamide expedites the process and enables the determination of small samples with low pigment level.Absorption spectra of Chi a, Chi b, and Pchl and of their acidified derivatives, the phaeophytins, were recorded. Conversion of Chi b to its corresponding acidified product occurs much more slowly than that of Chl a and Pchl. When acidffied, Pchl differs from Chl a and Chi b by the disappearance of the red band in the absorption spectrum. Specific extinction coefficients were determined and formulae for quantitative determination of pigments concentrations were developed. When concentrations of pigments are low, as in etiolated plant material, the absorption spectra of the chlorophylls can be distorted due to the presence of other substances simultaneously extracted; formulae for pigment determination under such circumstances were also derived.There is a vast array of solvents used for the extraction and determination of the Chl, but most of them necessitate grinding and centrifuging of material with or without heating t2, 5, 9). Recently, it was shown that the use of the solvent DMF renders the process simpler and faster, since the pigments can be extracted from intact tissues (I 1). A similar method which was described for green leaves, using ethanol, includes several repetitions of the extraction in relatively high volume (7). Another method was suggested, using dimethylsulfoxide. However, the tissue must be heated to 60°C (4).In a previous paper (11) Conversion of the Chl to their acidic derivatives was carried out according to (15) modified as follows: the nonacidified solution was stirred in the cuvette with a sealed pasteur pipette which was first dipped in a 5 N HCI solution. This treatment was repeated twice, although conversion of the pigments was almost complete after the first time. Change in volume was negligible. The change in pH was from 6.8 to 6.6 and was enough to enhance the total disappearance of the specific absorption spectrum of the Chl and the replacement by a stable spectrum of the corresponding acidic derivatives. All the SEC given for the phaeophytins are not corrected for loss of Mg, so that they can be utilized for the calculating of the concentrations of their corresponding Chl ( 18). RESULTSDetermination of SEC for the Chi: The SEC were determined by the equation:where Ax is the absorbance (OD units) at a given wavelength, EA is the SEC of the solution at wavelength A, c is the concentration (g/-L') and I is the beam-path (1 cm) in the measuring cuvette.For any AX, A2 in an interval where relation (1) holds, we have:The absorbances at the maxima of the main bands in the red of Chl b in 80% acetone and of Pchl in diethylether as solvents were compared with the absorbances of the corresponding maxima of

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Section: Resultssupporting

confidence: 93%

Formulae for Determination of Chlorophyllous Pigments Extracted with N,N-Dimethylformamide

Moran¹

1982

Plant Physiol.

1,239

637

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“…Figure 6(A) shows a chromatic shift of sample colour from green towards red (a* values become more positive). This e †ect is caused by the temperature-dependent degradation of chlorophyll to pheophytins (Mackinney and Joslyn 1941 ;Schwartz et al 1981 ;Yamauchi and Watada 1993). After 24 h of drying there was no signiÐ-cant di †erence in green colour (P \ 0É05) between 10É0 mm and 15É0 mm, but both were greener (P \ 0É05) than 5É0 mm samples.…”

Section: Resultsmentioning

confidence: 97%

Combined Effect of Drying Time and Slice Thickness on the Solar Drying of Okra

Adom

Dzogbefia

Ellis

1997

J. Sci. Food Agric.

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“…In the second degradation route the chlorophyll are degraded to chlorophyllide by chlorophyllase through removal of the phytol chain. This intermediate molecule is highly unstable and is further degraded to pheophorbide when exposed to acid or heat, by substitution of the Mg 2+ ion by two H + ions 28,29 . The two 14 degradation products have structural differences; the phytol chain is still present in pheophytin but is removed in pheophorbide, however they display similar absorbance spectra.…”

Section: Thermal Degradation Of Chlorophyllmentioning

confidence: 99%

The effect of heat treatment of thylakoids on their ability to inhibit in vitro lipase/co-lipase activity

et al. 2014

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The effect of heat treatment of thylakoids on their ability to inhibit in vitro lipase/colipase activity.Östbring, Karolina; Rayner, Marilyn; Sjöholm, Ingegerd; Otterström, Jennie; Albertsson, PerÅke; Emek, Sinan Cem; Erlanson-Albertsson, Charlotte General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal AbstractThylakoids has been shown to prolong lipolysis by the inhibition of lipase/co-lipase, which makes thylakoids suitable as a functional food ingredient with satiating properties. The components of thylakoids that provide its function as a lipolysis modulator are primarily photosystems I and II, which are structurally stabilised by chlorophyll. However, chlorophyll is known to be heat sensitive yet the enzymatic inhibiting capacity after heat treatment has not been previously studied. It was hypothesised that the retained function of thylakoids after heat treatment could be correlated to the degree of degradation. Heat treatment at either 60°C, 75°C or 90°C for time interval ranging from 15 sec to 120 min induced a color shift from bright green to olive brown which was attributed to degradation. The ability of heat-treated thylakoids to inhibit lipolysis in vitro was also reduced. A correlation between chlorophyll a degradation and the enzymatic inhibiting capacity could be established which opens possibilities to use a spectrophotometric method to quantify the ability of thylakoids to inhibit lipase/co-lipase in a more rapid and cost effective way to complement the pH-stat method used today. With the degradation pattern investigated, it is then possible to design a thermal treatment process to ensure a microbiological safe appetite-reducing product and at the same time minimize the loss of functionality.

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Chlorophyll-Pheophytin: Temperature Coefficient of the Rate of Pheophytin Formation

Abstract: 10-Thiocyanomethyl-1,2-benzanthracene; -, 9-thiocyano-10-methyl-l,2-benzanthracene.1.2-benzanthracene and 1,2-benzanthracene indicates that in spite of the considerable chemical reactivity and unsaturation of the thiocyano group,

Cited by 79 publications

References 0 publications

Formulae for Determination of Chlorophyllous Pigments Extracted with N,N-Dimethylformamide

Formulae for Determination of Chlorophyllous Pigments Extracted with N,N-Dimethylformamide

Combined Effect of Drying Time and Slice Thickness on the Solar Drying of Okra

The effect of heat treatment of thylakoids on their ability to inhibit in vitro lipase/co-lipase activity

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