Chemotropic Response of the Pollen of Antirrhinum majus to Calcium.

An improved spectrophotometric method for the determination of lipoxidase activity was developed and applied in studies of the purified enzyme and crude enzyme preparations from leguminous seeds, with linoleic acid solubilized in Tween 20 as the substrate. The optimum pH was found to be 7.0, 6.5, 6.0, and 5.5, for purified soybean lipoxidase and for the crude lipoxidases extracted from gram flour (Cicer sp.) soybean meal (Glycibic miax L.), and hy(lrate(l mung beans (Phaseolhs auircuEs L.), respectively. The application of this test illustrates A) that the present method was free from the inherent limitations on pH present in the original methods, B) that increasing the amount of detergent, in a fixed concentration of fatty substrate, caused inhibition in the enzymatic activity; more pronounced inhibitions occurred when the concentrations of detergent as well as of fatty substrate were increased in equal proportions, and C) peroxide formation is proportional to time of reaction and to enzyme concentration. Determination of lipoxidase activity in germinating mung beans indicated 3 periods of enzyme activity: a slow decline from 8 to 24 hours, a rapid decline from 24 to 40 hours, and a linear decline from 40 to 80 hours of germination. Literature Cited 1. BERGSTR6M, S. 1946. On the oxidation of linoleic acid with lipoxidase. Arkiv Kemi NMIinieral Geol. Band 21 A. No. 15. 2. FRITZ, G. J. 1962. Studies on 02-fixation by maize seedlings. Plant Physiol. 37: xxxii-xxxiii. 3. HOLMAN, R. T. AND S. BERGSTR6dM. 1951. Lipoxidase or unsaturated-fat oxidase. Inl: The Enzyme Chemistry and -Mechanism of Action, J. B. Sumner and K. NMyrbkck, eds. Academic Pres ILnc., New York. vol. 2, Part 1, 559-74. 4. HOILMAN, R. T. AND G. 0. BlURR. 1945. Spectrophotometric studies of the oxidation of fats. IV. Ultraviolet absorption spectra of lipoxidase-oxidized fats. Arch. Biochem. 7: 47-54. 5. HOLMAN, R. T. 1948. Lipoxidase activity and fat composition of germinating soy beans. Arch. Biochem. 17: 459-66. 6. HOLMAN, R. T. 1955. Measurement of Lipoxidase Activity. In: Methods of Biochemical Analysis, D. Glick. ed. Interscience Publishers, DNew York. vol II, 113-19. 7. TAPPEL, A. L. 1962. Lipoxidase. In: Methods in Enzymology, S. P. Colowick and N. 0. Kaplan, eds. Academic Press., New York anid London. vol 5, 539-42. 8. THEOREILI, H., S. BERGSTR6M, AND A. AKESON. 1946. Activity determination and further purification of lipoxidase. Pharm. Acta Helv. 21: 318-24.