THE HEME PROTEINS OF PHOTOSYNTHETIC 

 BACTERIA* 



MARTIN D. KAMEN 



University of California, San Diego 



La Jolla, California 



INTRODUCTION 



The area of research I have been asked to discuss was inaugurated 

 by an observation of Dr. L. P, Vernon when he and I were engaged in 

 collaboration (1,2) on energy- storage reactions in chromatophore 

 preparations in 1952. It is a source of particular satisfaction a decade 

 later to be here at this session sponsored by the C. F. Kettering Foun- 

 dation and its new research director, Dr. Vernon. 



The heme proteins of the photosynthetic bacteria have been con- 

 sidered in the past primarily from the standpoint of function. This is 

 so well documented now (3), even if still incompletely understood, that 

 I propose in this paper to adopt another approach— that is, to consider 

 the heme proteins as objects of intrinsic biochemical interest. To 

 paraphrase President Kennedy's famous exhortation— "Let us not ask 

 what heme proteins have done for photosynthesis, but what photosyn- 

 thesis has done for heme proteins!" 



CLASSIFICATION 



The index of progress in any science can be indicated by the status 

 of classification schemes. In the case of heme proteins, and natural 

 tetrapyrrole proteins in general, classifications based on function have 

 maintained a certain priority over those based on structure. This 

 follows, obviously, because it is usually easier to make functional 

 assignments than to solve structural problems, especially for im- 

 portant macromolecules of biological importance, such as proteins. 

 Thus, in the tetrapyrrole- conjugated proteins, which include the mag- 



Researches on which this paper is based were performed with the aid of sub- 

 sidies from the National Institutes of Health, National Science Foundation, and 

 the Charles F. Kettering Foundation, and have extended over a period of ten 

 years, beginning in 1953. My associates in chronological order have been L. 

 P. Vernon, J. W. Newton, R. G. Bartsch, T. Horio,J. A. Orlando, S. Taniguchi, 

 and K. Dus. 



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