The Influence of Salts on Pyruvate Kinase from Tissues of Higher Plants

A bstract. Succinyl CoA synthetase from Nicotiana tabacum exhibited a requirement for univalent and divalent cations. Mn2' replaced Mg2l in the assay medium and Co2' and Ca82 partially replaced Mg2+. Addition of Zn2' resulted in no enzyme activity. The enzvme was activated by univalent cations K+, Rb+, NH4+, and Na+; Li+ showed little or no activation. Maximum enzyme activity varied significantly with potassium salts of different anions.Greatest activation was obtained with K PO4 and, respectively, KCI, KNO1, K2SO4

contrasting

confidence: 55%

Influence of Certain Cations on Activity of Succinyl CoA Synthetase From Tobacco

Bush

1969

“…Previous investigation (9) has shown that neither Tris nor chloride ions appreciably influence the activity of pyruvate kinase. Experiments conducted to compare the inhibitory effect of Na+ or K+ molybdate with that of Tris molybdate showed no consistent differences.…”

mentioning

confidence: 99%

“…Sodium ions activated the enzyme slightly and Li+ and Ca+ + were inhibitory. Miller and Evans (9) demonstrated that pyruvate kinase from a series of higher plants also require K+, NH + or Rb+ and that a concentration near 0.04 N was necessary for maximum reaction velocity.…”

mentioning

confidence: 99%

Effect of Potassium & Other Univalent Cations on Activity of Pyruvate Kinase in Pisum sativum

Evans

1963

Self Cite

Potassium is a major component of both plant and animal organisms, yet information on the role of this element in metabolism is limited. A compilation (1) of the inorganic composition of many plant species reveals that a major portion of normal leaves contain from 1 to 4 % K+ on a dry weight basis. Potassium deficiency symptoms are noted when the K + contents of leaves range from 0.1 to 1.3 % of their dry matter. There are many general statements (3) to the effect that K+, Na+, and other ions that are present in biological materials in high concentrations function in the osmotic regulation of tissue fluids. Undoubtedly this is an important role of the so-called bulk ions, but relatively recent biochemical investigations (3) have provided convincing evidence that a series of enzyme systems require K+, NH4+ or Rb+ for activity and that the concentration of these ions needed for maximum reaction velocities is in the same range as the concentration of K+ in normal biological materials.

“…The extraction and assay of pyruvate kinase were conducted by using the slightly modified method described by Miller and Evans (12). For preparation of the extract, 2 g of leaves were homogenized in 10 ml of 50 mm tris buffer, pH 7.4, and the mixture was centrifuged at 25,000g for 10 min.…”

Section: Methodsmentioning

confidence: 99%

Influence of s-Triazines on Some Enzymes of Carbohydrates and Nitrogen Metabolism in Leaves of Pea (Pisum sativum L.) and Sweet Corn (Zea mays L.)

Singh

Salunkhe

1971

Foliar applications of 2 milligrams per liter of 2-chloro-4,6-bis(ethylamino)-s-triazine, 2-methylmercapto-4-ethylamino-6-isobutylamino-s-triazine, and 2-methoxy-4-isopropylamino-6-butylamino-s-triazine caused increases in the activities of starch phosphorylase, pyruvate kinase, cytochrome oxidase, and glutamate dehydrogenase 5, 10, and 15 days after treatment in the leaves of 3-week-old seedlings of pea (Pisum sativum L.) and sweet corn (Zea mays L). The results indicate that sublethal concentrations of s-triazine compounds affect the physiological and biochemical events in plants which favor more utilization of carbohydrates for nitrate reAuction and synthesis of amino acids and proteins.It is well established that the application of a sublethal concentration of s-triazines increases the protein in plants (5,6,13,(15)(16)(17)19). In a previous study (21), we noted an increase in protein content in leaves of pea and sweet corn after foliar application of 2 to 5 mg/l solutions of s-triazine compounds. Other metabolic and compositional changes following the application of s-triazines include an increase in total soluble amino acids, and the activities of nitrate reductase, transaminase, a-amylase, starch phosphorylase, adenosine triphosphatase, and 8-aminolevulinic acid dehydratase (17,18,20), and a decrease in starch and soluble sugars (16,21). In this study, the influence of foliar applications of 2 mg/l of simazine', igran, and GS-14254 on the activities of starch phosphorylase, pyruvic kinase, glutamate dehydrogenase, and cytochrome oxidase in the leaves of pea and sweet corn is described. MATERIAL AND METHODSPea (Pisum sativum L., var. Perfected Freezer) and sweet corn (Zea mays L., var. Iochief) seeds were sown in perlite in 1.5-liter plastic pots in the greenhouse. The plants were maintained at a 16-hr photoperiod of 25 to 27 C by lengthening ambient greenhouse day length with fluorescent light and 18 to 21 C dark temperatures. When the seedlings were 3 weeks old, 2 mg/l water solutions of simazine, igran, and GS-14254 were thoroughly sprayed on the leaves. Triton B-1956 (Rohm 1 Abbreviations: simazine: 2-chloro-4, 6-bis(ethylamino)-s-triazine; igran:2-methylmercapto-4-ethylamino-6-isobutylamino-s-triazine; GS-14254: 2-methoxy-4-isopropylamino-6-butylamino-s-triazine.and Haas, Philadelphia, Pa.) was used as a surfactant. Control plants were sprayed with a water solution of the surfactant only. The leaf samples were taken for enzyme assay at 5, 10, and 15 days following spray application.Starch phosphorylase was extracted by homogenizing 2 g of leaves in 10 ml of 0.1 M tris buffer, pH 6.3. The homogenate was centrifuged at 10,000g for 10 min. The supernatant fluid was used as a source of the enzyme. The enzyme assay was conducted by using the method of Lee (9). Inorganic phosphate was determined by an adaptation of the procedure of Fiske and Subbarow (7).The extraction and assay of pyruvate kinase were conducted by using the slightly modified method described by Miller and Evans (12). For preparati...