. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ARGINASE INHIBITION IN CHICK EMBRYOS 623 to-enzyme ratios. Consequently, enzyme does not exhibit the same fractional activity in all tissues and, therefore, inhibitor (s) must be playing some role in the differen- tiation process which results in each tissue having its characteristic arginase activity, as measured in homogenates. This suggests that the developmental decrease in activity could also be at least in part due to a change in inhibitor concentration. We have found that heart arginase activity decreases between the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ARGINASE INHIBITION IN CHICK EMBRYOS 623 to-enzyme ratios. Consequently, enzyme does not exhibit the same fractional activity in all tissues and, therefore, inhibitor (s) must be playing some role in the differen- tiation process which results in each tissue having its characteristic arginase activity, as measured in homogenates. This suggests that the developmental decrease in activity could also be at least in part due to a change in inhibitor concentration. We have found that heart arginase activity decreases between the eighth and the twenty-first day of incubation. At the twelfth day, heart ex- hibits a small but significant arginase activity and does not inhibit 4-day embryo arginase. At the twenty-first day, heart does not exhibit a measurable arginase UJ X UJ 450 350 (E ID $ 250 350 UJ \ 25° 21 DAY EMBRYO HEART. 12 DAY EMBRYO HEART 10 20 —I" 30 40 £ MGS. HEART/ML. REACTION MIXTURE FIGURE 6. Effect of heart from 12- and 21-day embryos on the arginase activity of 4-day embryos ( mg. per ml. reaction mixture) activated with 5 X 10~* M Mnh+. O embryo- heart mixture, X embryo activity + heart activity as measured separately. activity and inhibits 4-day embryo arginase (Fig. 6). These results show that a decrease in arginase activity is correlated with an increase in the ability to inhibit embryo arginase. Evidence presented in this section suggests that the arginase activity expressed by tissue homogenates is determined by the concentrations of both enzyme and inhibitor (s), different tissues contain different relative amounts of inhibitor to enzyme and that in one case the developmental decrease of arginase activity is correlated with an increase in inhibitory activity. We believe these results demon- strate that inhibitor (s) plays some role in the developmental change in arginase Please note that these images are extracted from scanned page images that may have been d
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
