THE ATYPICAL HAEMOPROTEIN OF PURPLE 

 PHOTOSYNTHETIC BACTERIA 



By M. D. Kamen* and R. G. Bartsch* 



Graduate Department of Biochemistry 

 Brandeis University, Waltham, Massachusetts 



INTRODUCTION 

 All PHOTOSYNTHETIC systciiis contain large amounts of haemoproteins bound 

 to photoactive subcellular aggregates (Kamen, 1957). These haematin 

 compounds are in many ways quite similar to those of the familiar respiratory 

 systems and can be included in the categories known to biologists since the 

 classic work of Keilin. However, there appears to be a novel type of haemo- 

 protein which can be extracted in soluble form from all the common species 

 of purple photosynthetic bacteria (Vernon and Kamen, 1954; Kamen and 

 Vernon, 1955; Newton and Kamen, 1956; Bartsch and Kamen, 1958) and 

 which cannot be placed in any single recognized class of haemoproteins, e.g. 

 cytochromes, haemoglobins, catalases, etc. On the occasion of the present 

 symposium, it is appropriate to summarize briefly our knowledge about this 

 atypical haemoprotein. 



GENERAL PROPERTIES 

 Distribution of the Atypical Haemoprotein {'RHP') 



The first specimen to be noted and isolated was found in trichloroacetic 

 acid extracts prepared from cell suspensions of the facultative photohetero- 

 troph, Rhodospirillum rubrum (Vernon and Kamen, 1954). At first, the 

 compound was thought, on spectroscopic grounds, to be a "pseudohaemo- 

 globin'. In further studies, the revelation of its anomalous character created 

 uncertainty mirrored in a series of progressively less definite names which 

 culminated finally in the present noncommittal 'Rhodospirillum haem protein' , 

 abbreviated to 'RHP'. We now customarily use 'RHP' to refer to all examples 

 of the atypical haemoprotein, regardless of the species from which it may be 

 obtained. 



RHP has been found in representative species of all the presently- 

 recognized genera of the purple non-sulphur bacteria (Athiorhodaceae) and 



* Publication No. 61 in the series 'Publications of the Graduate Department of 

 Biochemistry, Brandeis University.' 



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