Abstract
Sulfate uptake capacity and ATP-sulfurylase activity were determined in maize roots (Zea mays L. var. XL 363 and mutant XL 363 o2) at increasing root length. The pattern of uptake showed a close similarity to that of ATP-sulfurylase, both activities reaching the maximum level at 9 and 10 cm root length in the XL 363 and XL 363 o2 hybrids, respectively. In addition to the shift of the maximum, opaque-2 mutation caused an enhancement of the two activities at root length below and above the activity peak. The kinetic parameter of uptake, Km, showed a maximum at 3 to 4 and a minimum at 7 to 8 cm. The isoenzyme pattern of ATP-sulfurylase was the same in the two hybrids and did not change with root elongation. A common regulatory mechanism is postulated for uptake and activation of sulfate. The kinetic behavior is interpreted as an index of flexibility of the transport system toward different nutrient status of the environment.
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- Chantarotwong W., Huffaker R. C., Miller B. L., Granstedt R. C. In vivo nitrate reduction in relation to nitrate uptake, nitrate content, and in vitro nitrate reductase activity in intact barley seedlings. Plant Physiol. 1976 Apr;57(4):519–522. doi: 10.1104/pp.57.4.519. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Crowley P. H. Natural selection and the Michaelis constant. J Theor Biol. 1975 Apr;50(2):461–475. doi: 10.1016/0022-5193(75)90093-4. [DOI] [PubMed] [Google Scholar]
- JACOB F., MONOD J. Genetic regulatory mechanisms in the synthesis of proteins. J Mol Biol. 1961 Jun;3:318–356. doi: 10.1016/s0022-2836(61)80072-7. [DOI] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Onajobi F. D., Cole C. V., Ross C. Adenosine 5'-triphosphate-sulfurylase in corn roots and its partial purification. Plant Physiol. 1973 Dec;52(6):580–584. doi: 10.1104/pp.52.6.580. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pardee A. B. Membrane transport proteins. Proteins that appear to be parts of membrane transport systems are being isolated and characterized. Science. 1968 Nov 8;162(3854):632–637. doi: 10.1126/science.162.3854.632. [DOI] [PubMed] [Google Scholar]
- Righetti P., Drysdale J. W. Isoelectric focusing in polyacrylamide gels. Biochim Biophys Acta. 1971 Apr 27;236(1):17–28. doi: 10.1016/0005-2795(71)90144-9. [DOI] [PubMed] [Google Scholar]
- WILSON L. G., BANDURSKI R. S. Enzymatic reactions involving sulfate, sulfite, selenate, and molybdate. J Biol Chem. 1958 Oct;233(4):975–981. [PubMed] [Google Scholar]