Mitochondrial malate dehydrogenase of watermelon cotyledons: Time course and mode of enzyme activity changes during germination
✍ Scribed by R.-A. Walk; B. Hock
- Publisher
- Springer-Verlag
- Year
- 1976
- Tongue
- English
- Weight
- 555 KB
- Volume
- 129
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Specific antibodies were prepared against the purified mitochondrial malate dehydrogenase (EC 1.1.1.37) from cotyledorLs of watermelon seedlings (Citrullus vulgaris Schrad.). The isoenzyme was assayed by means of quantitative radial immunodiffusion. Cotyledons of ungerminated seeds were found to contain mitochondrial MDH. During the first 4 days of germination the enzyme activity increased threefold finally contributing 16% to the total MDH activity extracted from cotyledon tissue. Isopycnic CsC1 density centrifugation was used to investigate the mode of activity increase. After a four-day period of labelling with deuterium oxide and purification of the mitochondrial isoenzyme, a density shift of 0.021 kg x 1-1, accompanied by considerable band broadening of the enzyme profile was observed. These findings are evidence for the de novo synthesis of mitochondrial MDH and its relatively slow turnover in germinating seeds.