CHEMICAL KINETICS OF THE HILL REACTION 



377 



However, by the use of equation 2 we can, and routinely do, extra- 

 polate through some inverted linear form of this equation to zero 

 and infinite light intensities at which conditions all three of the equa- 

 tions give identical results. The two rate parameters k^^ and ko can 



_ 0. 5 



i/v 



0.4 



0. 3 



— 0.2 



0. 1 



RELATIVE LIGHT INTENSITY (I) 



Fig. 1. Curves showing the rectangular liypeiboiic nature of the Hill reaction- 

 light intensity relationship for isolated chloroplasts. Each point represents 

 the mean of eight separate rate measurements. Here / is the relative incident light 

 intensity in aibitrary units, while V is the rate expressed hi terms of moles ferri- 

 cyanide reduced per mole chlorophyll per minute. The initial ferricyanide concen- 

 tration was ().()()()2o.U, the pH was 0.80, and the temperature was 2.5°C. 



thus be determined by least-squares extrapolation. This permits the 

 calculation of the true steady-state rate at any intensity, providing 

 the true microscopic rate law is given by equation 2. A set of data 

 obtained under controlled conditions is shown in Fig. 1. The data 

 given are the means of eight sets of measurements and arc plottetl 



