Stopped-flow experiments 221 calcium

For a fast chemical reaction, such as the determination of calcium by o-cresolphthalein using colorimetric detection at 580 nm [253], shown in Fig. 2.32b, the product formation is so rapid that the response curve is identical with the dispersion curve obtained if product were injected as such. This is readily seen from the zero slope (dRIdt = 0) of the reaction rate curve A = B recorded with the element of fluid at the peak top (at CT , using delay time tdi). The same stopped-flow experiment repeated at the peak gradient (at Ca, using delay time r z) again has a zero slope... 

Figure 4.5 (a) Kinetics of the reaction of aequorin with maximally ective concentration of (0.02 M) at 20 C in a stopped-flow apparatus. Aequorin 2.5 ng ml" in the reaction mixture. Three successive experiments were recorded with sweep speeds of 5, 50 and 500 ms per division, (b) A double stopped-flow experiment at 26 C in which aequorin 0.7 pg ml" and calcium 0.1 M were first mixed and the resulting solution was mixed with 0.1 M EDTA sweep speed 5 ms per division. (For further detail see Hastings et al., 1969.)... 

Lobster hemocyanin in glycine-sodium hydroxide buffer at pH 9.6 undergoes a reversible whole molecule-half molecule dissociation which is very sensitive to the level of free calcium ion present (12). This dissociation process is also very sensitive to pH (12). Cann and colleagues have developed, by simulation techniques (13,14), a general picture of the kinds of partial or complete boundary resolution that may be expected for such coupled systems in various types of transport experiments. Kinetic investigations of the lobster hemocyanin system under the conditions of the present study were developed by using stopped-flow... 

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