The mechanism of the repression by inorganic phosphate of phytase synthesis in the germinating wheat embryo

Bianchetti, Renato; Sartirana, M. L.

doi:10.1016/0005-2787(67)90066-4

Cited by 35 publications

(11 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar type of induction of other enzymic activities in germinating seeds has been reported in other cases as well (14). That the degradation of phytate in the developing wheat embryo in isolated culture is regulated by the level of inorganic phosphate in the medium has been shown by others (3,20). This regulation by inorganic phosphate has been shown to be effected by the repression of phytase synthesis at the transcriptional level in this growing tissue.…”

Section: Discussionsupporting

confidence: 79%

Metabolism of Inositol Phosphates

Mandal

Biswas

1970

Plant Physiol.

View full text Add to dashboard Cite

The degradation of phytin in germinating mung bean seeds has been found to be associated with the increased activity of phytase in the cotyledon. In the differentiated embryo the increase of this activity is very low all throughout the growth periods studied. Phytase appears in the cotyledon during germination. No activity has been detected in the cotyledons of unsoaked seeds. Cycloheximide (10-6 M) inhibits the appearance of phytase by 61% during 24 and 48 hours after the start of germination. This phytase increase is dependent on the synthesis of new RNA in the cotyledon. Synthesisof DNA is not detected inthe cotyledon during germination.Phytase or myoin-ositol hexaphosphate phosphohydrolase (EC 3.1.3.8) which carL hydrolyze myoinositol hexaphosphate to myoinositol and inorganic phosphate has long been known (23). Pears (18) showed that in ungerminated wheat the aleurone portion contained 39%, endosperm 34%, and scutellum 15% of the total phytase activity of the whole seeds. It has also been shown by different groups of workers that phytase activity of different grains increases during germination (1,12,15). Many reports are now available on the characteristics of the enzyme phytase. Nagai and Funahashi (17) reported a phytase, purified 1500-fold from wheat bran, which shows broad substrate specificity at pH 5.0. Gibbins and Norris (6) purified phytase and an acid phosphatase from the cotyledons of germinated Phaseolus vulgaris, the pH optimum of which has been recorded at 5.0. In the present study the activity of phytase in the cotyledons of mung bean seeds (Phaseolus aureus) has been found to be increased after soaking for 24 hr. The pH optimum for this system has been recorded at 7.5 instead of 5.0, the level reported with various preparations from different seeds. Very little phytase activity has been detected in the cotyledons of mung bean seeds after soaking for 6 hr. Regarding the appearance of phytase activity there may be two possibilities: (a) de novo synthesis or (b) activation of enzyme protein already present in the seeds. From the present study it appears that phytase is synthesized de novo in the cotyledon of mung beans after soaking. Research Institute, Pussa, Bihar. "4C-Amino acid mixture, 2-14C-uridine, and 2-'4C-thymidine were obtained from Radiochemical Centre, Amersham, Buckinghamshire, England. Cycloheximide was procured from Nutritional Biochemical Corporation, Cleveland, Ohio. Chromomycin A3 was obtained as a gift from Takeda Chemical Industries, Ltd., Osaka, Japan. MATERIALS AND METHODSIsolation of Phytate. Phytate was isolated from mung bean by extraction with 1 M HCl04 (4) and separated by gradient elution chromatography on a Dowex 1-Cl column (19).Germination Procedure. The dry seeds of mung beans (Phaseolus aureus) were washed with water for 5 min and then covered with water (3 ml/g of seed) in a large Petri dish with seeds dispersed uniformly over the dish. The Petri dish was then covered, allowing for a little air passage, and kept at 35°in an incubator. After the seeds ...

show abstract

Section: Discussionsupporting

confidence: 79%

Metabolism of Inositol Phosphates

Mandal

Biswas

1970

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…A greater reduction (39-75%) was found in the cotyledons of other legumes such as the pea, soybean, Phaseolus aureus, chickpea and Cajanus cajan (Chitra et al, 1996). The different reduction percentages observed, might be related to different activities of endogenous phytases, due to an increase while being synthesised de novo (Bianchetti and Sartirana, 1967) or when pre-existent phytases are activated (Greiner et al, 2002). Hydrolysis products of IP 6 and IP 5 (IP 3 and IP 4 ) did not accumulate, but decreased possibly because of rapid dephosphorilation to myoinositol and inorganic phosphate required for embryo axis development (Loewus and Murthy, 2000).…”

Section: Cotyledonsmentioning

confidence: 59%

Content and distribution of protein, sugars and inositol phosphates during the germination and seedling growth of two cultivars of Vicia faba

Goyoaga¹,

Burbano²,

Cuadrado³

et al. 2011

Journal of Food Composition and Analysis

View full text Add to dashboard Cite

“…Similarly, inorganic phosphate is ineffective if applied after the first 6 hours. The interpretation of these results is that inorganic phosphate represses phytase synthesis only during the period of phytase mRNA synthesis, that is, that inorganic phosphate acts at the level of transcription (91).…”

Section: Nitrate Reductase Has Been Discussedmentioning

confidence: 96%

“…The increase of phytase in the scutellum of germinating wheat embryo is completely abolished by 3 X 10-4 mole of puromycin per liter or 80 micrograms of actinomycin D per milliliter (91). Because inorganic phosphate also abolishes the increase in enzyme activity, it is concluded that phosphate represses the synthesis of phytase.…”

Section: Nitrate Reductase Has Been Discussedmentioning

confidence: 97%