![](img015.GIF) |
We turned our
attention to an examination of guanylyl cyclase in cell-free systems. We
learned that there was enzyme activity in both high-speed supernatant and
particulate fractions of most tissue homogenates. Furthermore, the
activities were quite different. While ATP inhibted both activities, the
soluble activity was more sensitive to ATP inhibition. Calcium ion could
either activate or inhibit activity dependent upon its concentration, but
the soluble and particulate activates had different sensitive to these
effects. |