. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CYTOCHROMES OF MARINE BIVALVES 127 o LO Q_ O 30 60 90 120 TIME (SECONDS) 150 180 FIGURE 1. The oxidation of reduced cytochrome c by cytochrome oxidase from oyster gill. Reduced cytochrome c was prepared by reduction with a pinch of hydrosulphite and the excess hydrosulphite oxidized by shaking. Total volume 3 ml. Each cuvette contained final concen- tration of 2 X 10-5 M cytochrome c, M phosphate buffer at pH and ml. of the extract. I contained 10~3 M cyanide; II, no cyanide. Reaction was follow
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CYTOCHROMES OF MARINE BIVALVES 127 o LO Q_ O 30 60 90 120 TIME (SECONDS) 150 180 FIGURE 1. The oxidation of reduced cytochrome c by cytochrome oxidase from oyster gill. Reduced cytochrome c was prepared by reduction with a pinch of hydrosulphite and the excess hydrosulphite oxidized by shaking. Total volume 3 ml. Each cuvette contained final concen- tration of 2 X 10-5 M cytochrome c, M phosphate buffer at pH and ml. of the extract. I contained 10~3 M cyanide; II, no cyanide. Reaction was followed at 25° C. The change of optical density was plotted on the logarithmic scale. represents the results of these observations. The cytochromes are most abundant in the heart, where cytochrome c is predominant or equal to b. In other tissues, however, cytochrome b is apparently more dominant than a + az or c. This fact forms a sharp contrast to the situation of the heart. Absence of the bands of a + a, or c in certain tissues may be due to their very low concentration. When a few drops of pyridine were added to the reduced tissues, a very intense pyridine hemochromogen band extending from about 550 to 560 m/i, with a mid-point at about 557 m/A, and a wreak band lying about from 580 to 590 m^ were readily produced in all tissues examined. They are considered to be the absorption bands of pyridine derivatives of cytochromes b and a group, respectively. 2. Cytochrome oxidase The enzyme activity was determined at 25° C. by two methods, , mano- metrically and spectrophotometrically. The extract for the enzyme study was prepared by homogenizing the excised tissue with a glass homogenizer in five parts of cold M sucrose (isotonic with sea water) and squeezing through a thin cloth. The addition of an aliquot of the extract to a solution of reduced cytochrome c results in a rapid decrease in optical density at 550 m^t, (Fig. 1). The activity of molluscan cytochrome oxidase is
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
