. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SULFIDE OXIDATION ACTIVITY S. reidi FOOT l/v (U-gfw ). (mM) FIGURE 1. Double-reciprocal (Lineweaver-Burk) plots of sulfide oxidation activity of Solemya reidi gill (Top) and foot (Bottom) supernatants. Activities are expressed as international units per g fresh weight (U • gFW '). For Figure 1B (Bottom), open circles and dashed line (- -) represent mg fresh weight used per assay, and closed circles and solid line (— —) represent mg fresh weight used per assay. Best fit straight l
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SULFIDE OXIDATION ACTIVITY S. reidi FOOT l/v (U-gfw ). (mM) FIGURE 1. Double-reciprocal (Lineweaver-Burk) plots of sulfide oxidation activity of Solemya reidi gill (Top) and foot (Bottom) supernatants. Activities are expressed as international units per g fresh weight (U • gFW '). For Figure 1B (Bottom), open circles and dashed line (- -) represent mg fresh weight used per assay, and closed circles and solid line (— —) represent mg fresh weight used per assay. Best fit straight lines were calculated using a weighted linear regression program. Km of an extract prepared from the surface of foot tissue was ± when mg fresh weight were used and ± when mg fresh weight were used. Protease treatment of gill supernatant from S. reidi resulted in up to an 80% loss in sulfide oxidizing activity, and boiling for 30 min caused a 50% loss of activity (Table III). Electrophoresis of S. reidi gill homogenates on native acrylamide gels, followed by sulfide oxidation activity staining, resulted in a single band in the separating gel exhibiting activity, as well as a band at the interface between the stacking and separating gel (data not shown). These results suggest that the sulfide oxidizing activity in S. reidi is due to the activity of one or more "sulfide oxidase" enzyme systems. In contrast to the results obtained with extracts of tissues from S. reidi, the sulfide oxidizing activities of the protein solutions and the tissue extracts of animals from low-sulfide habitats showed no evidence of substrate (sulfide) saturation at sulfide concentrations up to 10 mM (the highest concentration compatible with the benzyl viologen assay system). These sulfide oxidizing activities appear not to be due to a specific "sulfide oxidase" enzyme having Michaelis-Menten kinetics. The factor responsible for the activity is proba
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
