Proteus vulgaris system

According to Mizuno and coworkers,59 the reticuloendothelial system was strongly stimulated by the intracutaneous injection of the lipopolysaccharide of Proteus vulgaris, and a marked antitumor effect... 

Huberman and Rittenberg (126a) find that Proteus vulgaris contains an enzyme that catalyzes the exchange reaction Ha + Da. The enzyme is inhibited by CO and HCN and they tentatively conclude that it is a ferrous heme system. 

A few organic mediators are used such as ArsN/ArsN" for oxidations and viologens for reductions. One special example is the electromicrobial reduction of an a-keto acid to an a-hydroxy acid using the enzyme system of Proteus vulgaris (Ep) and methyl viologen (MV) as the electron shuttle (Scheme 5, Fig. 8) [124]. 

In animal tissues cysteinesulfinic acid can undergo transamination, decarboxylation, and oxidation. In certain strains of Proteus vulgaris an alternative oxidation and transamination operate simultaneously 18). It was shown by Cohen 19) and by Kearney and Singer 18) that both in animal and microbial systems the transamination of cysteine sulfinate catalyzed by glutamate-aspartate transaminase proceeds as follows ... 

The third reaction, the oxidation of cysteine sulfinate, proceeds differently in Proteus vulgaris and in animal tissues. As shown by Singer and Kearney 18,20) the Proteus enzyme system oxidizes it directly to cysteate. This oxidation requires a pyridine nucleotide coenzyme which appears to be closely related to DPN+ 23). On the other hand, in rat liver mitochondria a soluble enzyme system oxidizes L-cysteine sulfinate in the presence of DPN+ to j8-sulfinylpyruvate and NH3 20). This reaction is analogous to that catalyzed by glutamic dehydrogenase [see Eq. (7)]. There is some indication that kidney n-amino acid oxidase can also oxidize cysteine sulfinate 24). Among these pathways of cysteine sulfinate metabolism the transaminative one is of the greatest importance. 

Another problem was to find a stable and cheap mediator and an effective regeneration system for the oxidized mediator. Table 14 shows the activity of different mediators. Under various aspects anthraquinone-2,6-disulphonate was especially useful. It is completely stable under the reaction conditions and can easily be reisolated if necessary. It works not only veiy well with HVOR but also with dimethyl-sulphoxide reductase present in Proteus mirabilis or P. vulgaris (Scheme 4). 

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