Flavocytochrome prosthetic groups structure

Tyr 143, 36 293 Tyr 254, 36 291-293 NMR spectroscopy, 36 271-272 pH dependence, 36 274-275 primary stmcture, 36 261-263 prosthetic groups structure, 36 258 quaternary structure, 36 261-262 reduction potentials, 36 268-269 short electron transport chain, 36 258-259 site-directed mutagenesis, 36 289-290 substrate specificity, 36 272-274 Flavocytochrome C552 electrochemistry, 36 365-367, 369... 

Fig 1. Structure of the flavocytochrome prosthetic groups—protoheme IX and flavin mononucleotide. 

In 1915, Harden and Norris observed that dried yeast, when mixed with lactic acid, reduced methylene blue and formed pyruvic acid 4). Thirteen years later Bernheim prepared an extract from acetone-dried baker s yeast, which had lactate dehydrogenase activity (5). Bach and co-workers demonstrated that the lactate dehydrogenase activity was associated with a 6-type cytochrome, which they named cytochrome 62 (6). In 1954, the enzyme was crystallized, enabling the preparation of pure material and the identification of flavin mononucleotide as a second prosthetic group (2). Since then, significant advances have been made in the analysis of the structure and function of the enzyme. Much of the earlier work on flavocytochrome 62 has already been summarized in previous review articles (7-10). In this article we shall describe recent developments in the study of this enzyme, ranging fi om kinetic, spectroscopic, and structural data to the impact of recombinant DNA technology. 

Fig. 3. The three-dimensional structure of Saccharomyces cerevisiae flavocytochrome 62 as determined by Xia and Mathews (25). (A) The C-terminal tails and flavin mononucleotide (FMN) and heme prosthetic groups are highlighted in this view, which is looking down the fourfold axis of symmetry. The four subunits are numbered 1 to 4 the shaded portions seen in the subunits labeled 2 and 4 represent the two heme domains, which are disordered in the structure. (B) A side view, perpendicular to view A, is also shown. 

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