. Il bollettino biologico. Biologia; Zoologia; biologia; biologia marina. 56 S. W. JEFFREY E KAZUO SHIBATA. 350 400 500 600 di lunghezza d'onda 700 in figura 1. Spettro di assorbimento (curva A) di clorofilla c in metanolo assoluto come com- pared con che (curva B) in 1:3 miscela metanolo-acqua a pH 7.3. Le concentrazioni di clorofilla c in queste misurazioni erano identici. essere interpretato come dovuto alla polimerizzazione della clorofilla c molecole, il rapporto più elevato, 9.4, ottenuti a concentrazioni inferiori possono essere il più corretto rapporto di clorofilla monomerica c in particolare preparazione studiata. Lo spettro

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. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 56 S. W. JEFFREY AND KAZUO SHIBATA. 350 400 500 600 Wavelength in 700 FIGURE 1. Absorption spectrum (curve A) of chlorophyll c in absolute methanol as com- pared with that (curve B) in 1:3 methanol-water mixture at pH 7.3. The concentrations of chlorophyll c in these measurements were identical. be interpreted as due to polymerization of chlorophyll c molecules, the higher ratio, 9.4, obtained at lower concentrations may be the more correct ratio for monomeric chlorophyll c in the particular preparation studied. The spectrum of the chlorophyll c preparation in acetone showed Soret and red maxima at wavelengths (453 and 628 mju, ) slightly different from those in methanol. The band ratio was 9.4, being identical with the ratio obtained with methanol at lower chlorophyll c concentrations. The ratio determined previously (Jeffrey, 1963) with acetone immediately after purification of chlorophyll c was 9.3 while the ratio decreased to 6.9-8.1 during storage for more than 2 hours at --20°. The present result confirmed the previous value obtained immediately after purification. The flattening of the Soret band after purification might have been due to aggrega- tion of chlorophyll molecules, made possible by the removal of the last traces of lipid from the preparation and storage at low temperatures. Similar flattening effects of the Soret band were found in the present work by the addition of water to acetone or methanol solutions of chlorophyll c. An example of the effect of water on the absorption spectrum of chlorophyll r is •shown by curve A in Figure 2, which shows the spectrum of chlorophyll c in a 5:1 methanol mixture (17% water by volume) at an apparent pH of 7.4. On the addition of water, the Soret maximum shifted to a shorter wavelength of 448 rr% but the red maximum did not alter (634 m/j.). The band ratio fell to 8.2. This ratio was confirmed by repeated measurements, and was significantly

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• bookauthorlilliefrankrat
• booksubjectbiology
• booksubjectzoology