Hueinoprolcin of Purple Photosynthetic Bactei 



425 



moves approximately 10 m/j, toward the blue. Because of its extreme photo- 

 instability at physiological pH, the complex absorption spectrum must be 

 measured in very weak light. 



5. The a-band of the reduced form is diffuse and appears to consist of at 

 least two components. These are easily seen using a Hartridge reversion 



; \ OXIDIZED CHROMATIUM RHP 



REDUCED CHROMATIUM RHP 



450 500 550 



WAVELENGTH (m>j) 



Fig. 3. Spectrum of oxidized and reduced Chiomatium RHP at pH 6-^ 



spectroscope, but are hardly discernible in the Gary traces, particularly those 

 of the R. rubrum compound. The wavelength maxima shown in Fig. 3 are 

 those determined visually, using the spectroscope. The absence of a j3-band 

 in the usual position (approx. 520-525 m^) is another criterion employed 

 in monitoring RHP. 



6. The haemochrome spectrum of RHP found in alkaline medium 

 (Fig. 4) exhibits absorption maxima located at the same positions as those of 

 corresponding cytochrome c at physiological pH, but relative intensities of the 

 absorption peaks differ markedly (Bartsch and Kamen, 1958). 



In Table 2 we have listed values for a number of extinction coefficients, 

 both for absolute and difference absorption spectra. The preparations 

 measured all had purities in excess of 95%, based on spectroscopic data. 

 They were homogeneous by criteria based on sedimentation and diffusion 

 studies. 



