Acetylcholine Inhibition of Phytochrome-mediated Increases in a Flavonoid and in Phenylalanine Ammonia-Lyase Activity of Etiolated Barley Plumules

Saunders, James A.; McClure, Jerry W.

doi:10.1104/pp.51.2.407

Cited by 13 publications

(8 citation statements)

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“…As an equivalent amount of phenylpyruvate would be formed in this reaction, this would lead to an increased absorbance of about 0.00003 per min using e 290 nm of 2950 for phenylpyruvate in the pH 8.8 borate buffer (3). This is considerably less than the error term in spectrophotometric assays for PAL from most seedlings (2,(6)(7)(8)(9). This level of phenylpyruvate formation is similar to that found in crude extracts of pea shoots (5).…”

supporting

confidence: 67%

“…As we have used this spectrophotometric assay for the quantitative determination of PAL in barley (6-8), we attempted to determine the extent to which traces of a-keto acids present in our crude extracts might lead to the formation of complexes interfering in the assay. PAL levels in peas and in buckwheat have been examined by several techniques (1,2) (8). All manipulations of the etiolated plants, from soaking the seeds through centrifuging the enzyme preparations, were carried out in the dark or under a dim green safelight (8).…”

mentioning

confidence: 99%

“…PAL levels in peas and in buckwheat have been examined by several techniques (1,2) (8). All manipulations of the etiolated plants, from soaking the seeds through centrifuging the enzyme preparations, were carried out in the dark or under a dim green safelight (8).…”

mentioning

confidence: 99%

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The Suitability of a Quantitative Spectrophotometric Assay for Phenylalanine Ammonia-lyase Activity in Barley, Buckwheat, and Pea Seedlings

Saunders¹,

McClure²

1974

Plant Physiol.

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It has been suggested by others that the spectrophotometric assay of phenylalanine ammonia-lyase based on changes in absorbance at 290 nm may be complicated by a side reaction involving transamination from phenvlalanine onto a-keto acids. This would lead to the production of phenylpyruvate which would spontaneously tautomerize and form an enol borate complex absorbing at this wavelength. We find that the inclusion of 1 ml of either 60 gM a-ketoglutarate or 500 ItM phenylpyruvate in our 3-ml reaction mixtures has no significant effect on the spectrophotometric assay of phenylalanine ammonia-lyase in shoots from young seedlings of barley (Hordeum rulgare), buckwheat (Fagopyrum esculentum), or pea (Pisum sativum). Although these side reactions may be involved in preparations with very low enzyme activity, the spectrophotometric determination of phenylalanine ammonia-lyase based on changes in absorbance at 290 nm appears to be a reliable and sensitive technique in these seedlings. Erez (3) has pointed to possible errors in the widely Used spectrophotometric assay of phenylalanine ammonia-lyase based on increased absorbance at 290 nm of cell-free preparations in pH 8.8 borate buffer (9). PAL2 deaminates L-phenylalanine to produce trans-cinnamic acid which absorbs strongly at 290 nm under these conditions. He suggests that under optimal conditions for PAL activity and in the presence of aminotransferases and a-keto acids, phenylalanine may be diverted into phenylpyruvate which will tautomerize and fcrm an enol tautomer-borate complex interfering with the assay. As we have used this spectrophotometric assay for the quantitative determination of PAL in barley (6-8), we attempted to determine the extent to which traces of a-keto acids present in our crude extracts might lead to the formation of complexes interfering in the assay. PAL levels in peas and in buckwheat have been examined by several techniques (1, 2), and these plants were included for comparative purposes.

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confidence: 67%

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confidence: 99%

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The Suitability of a Quantitative Spectrophotometric Assay for Phenylalanine Ammonia-lyase Activity in Barley, Buckwheat, and Pea Seedlings

Saunders¹,

McClure²

1974

Plant Physiol.

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“…Consider the sleep movements of leaves (23 (68,85,125) and against (87,121,142,158) (109) and that both phytochrome and auxin affect proton pump activity.…”

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confidence: 99%

“…These rapid phenomena could be ascribed more logically to changes in the membrane, and it was thus inferred that phytochrome acts through control of membrane properties (45), much as rhodopsin is known to do (59). Such a mechanism of action could also account for control of gene activity, either through localization of phytochrome in the nuclear envelope (50) (68,85,125) and against (87,121,142,158) In our previous discussion of photomorphogenesis, we noted that many processes besides flowering are controlled by phytochrome, and that the nature of these processes influenced the kinds of theories advanced to explain the mechanism of phytochrome action. In the same vein, other light-controlled processes in plants, described below, have action spectra sufficiently similar to that for the phototropic curvature of grass coleoptiles as to make it logical to ascribe them to the same photoreceptor.…”

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Plant Photobiology in the Last Half-Century

Galston

1974

Plant Physiol.

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The absorption of light energy not only nourishes the plant through photosynthetic phosphorylation and concomitant carbon dioxide fixation, but it also determines the nature and the direction of plant growth. This review will summarize the major advances in the physiology of both of the latter processes over the last half-century. Because of severe limitations of space, only a few key concepts can be mentioned, let alone emphasized, and some fields, like algal phototaxis, must be omitted entirely.Although there was certainly provocative earlier work by Klebs and others (100) (49,144). Although a definite conclusion cannot yet be made, the bulk of recent evidence favors the flavin hypothesis. I shall try to summarize this evidence and certain other aspects of the physiology of phototropism as well. Although experimentation in phototropism has been relatively quiescent for about 20 years, recent developments provide encouragement for new insights into this process.Some methodological problems are unique to this kind of biology. Decisions about photoreceptor pigments depend on correlations between action spectra for the process and absorption spectra for the pigment (10,160). Light, to be effective, must first be absorbed, and in energy ranges where photon absorption limits the rate or extent of a process, there should be rough correspondence between regions of the spectrum that are most active in eliciting a process and regions of high light absorption by the pigment. One cannot push these coincidences too far, however, because other pigments can act as light screens, differential refraction of different wavelengths inside the tissue can produce distortion in relative actinic effectiveness, attachment of pigments to different proteins can 1 Dedicated to the memory of Harry A. Borthwick, a wise and compassionate man. Generous support from the National Science Foundation has made possible the author's active involvement in this field for more than 20 years. alter their absorption properties in different ways, resonance transfer of energy between pigments or unequal quantum efficiencies at different wavelengths can alter curves, and dichroic orientation of a pigment in a lamella may produce aberrant or unrepresentative values. Despite these caveats, action spectra remain the major method for inferring the nature of the photoreceptor (130,131).Action spectra are prepared by doing dose-response energy experiments at each of the wavelengths employed. From such data, provided that the reciprocity law holds, one can calculate the energy required to produce a standard effect, e.g. 50% promotion of seed germination. When corrected for the different energy of quanta in the different portions of the spectrum and transformed to reciprocal values, these data tell us the relative effectiveness of quanta in producing the observed physiological effect. A plot of this parameter against wavelength gives the standard action spectrum.Deducing the nature of the photoreceptor pigment is only the first step along the difficult road of ...

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The Physiology of Phenolic Compounds in Plants

McClure

1979

Biochemistry of Plant Phenolics

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Acetylcholine Inhibition of Phytochrome-mediated Increases in a Flavonoid and in Phenylalanine Ammonia-Lyase Activity of Etiolated Barley Plumules

Cited by 13 publications

References 3 publications

The Suitability of a Quantitative Spectrophotometric Assay for Phenylalanine Ammonia-lyase Activity in Barley, Buckwheat, and Pea Seedlings

The Suitability of a Quantitative Spectrophotometric Assay for Phenylalanine Ammonia-lyase Activity in Barley, Buckwheat, and Pea Seedlings

Plant Photobiology in the Last Half-Century

The Physiology of Phenolic Compounds in Plants

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