Micrococcus lactilyticus

Xanthine dehydrogenase Micrococcus lactilyticus Purines, aldehydes Ferredoxin... 

Xanthine dehydrogenase from chicken liver reacts readily with NAD as acceptor (77) while that from Micrococcus lactilyticus is inactive towards this, reacting instead with ferredoxin (18). Both enzymes react only slowly with oxygen. It seems reasonable to assume, however, that for each member of this group of enzymes, reducing substrates all react via molybdenum, as in milk xanthine oxidase. Presumably, different... 

So little is known about molybdenum enzymes other than milk xanthine oxidase that there is little to be said by way of general conclusions. In all cases where there is direct evidence (except possibly for xanthine dehydrogenase from Micrococcus lactilyticus) it seems that molybdenum in the enzymes does have a redox function in catalysis. For the xanthine oxidases and dehydrogenases and for aldehyde oxidase, the metal is concerned in interaction of the enzymes with reducing substrates. However, for nitrate reductase it is apparently in interaction with the oxidizing substrate that the metal is involved. In nitrogenase the role of molybdenum is still quite uncertain. 

Woolfolk, C.A. and Whiteley, H.R., 1962. Reduction in inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. J. Bacteriol., 84 647—658. 

Micrococcus lactilyticus and some Clostridia. The propionibacteria and M. lactilyticus fermented lactate better than Clostridia and, in contrast with the latter, their fermentation activity was not inhibited by high concentrations of sugars. All the bacteria indicated above are anaerobic, and it is imder anaerobic conditions that important biochemical processes occur in silage. 

A preparation (Wright and Anderson, 1958) from Clostridium sticklandii catalyzed the reaction PGA + pyruvate + CoA — acetyl CoA + FH2. Since the diglutamyl and triglutamyl pterins and their J T -formyl derivatives were reduced, such a reductase system can account for the transformation of exogenous PGA into the reduced coenzymatic products. An enzyme from Micrococcus lactilyticus formed FH2 the reaction required an electron donor such as pyruvate or a-ketobutyrate, a dithiol such as dimer-captopropanol, orthophosphate, and reduced CoA. This enzyme did not form FH4 derivatives. 

FA pterins excepted, nothing is known about pterins in bacteria. Xanthine oxidase is present in Lactobacillus casei (Villela et d., 1955) and Micrococcus lactilyticus (Whitely and Ordal, 1956). 

Whiteley (396-398) prepared cell-free extracts of Micrococcus lactilyticus which were very active in catalyzing the decarboxylation of succinate at a pH optimum of 5.2, and with a partial requirement for Mg++ and possibly diphosphothiamine. Treatment of the extracts with anion-exchange resins makes the reaction dependent on the addition of both ATP and CoA. Under these conditions they can also be shown to convert succinate to succinyl-CoA. These extracts catalyze the evolution of CO from succinyl-CoA in the absence of added cofactors. Some evidence was obtained for the production of succinate from propionate and CO in the presence of ATP and CoA. Since decarboxylation of relatively large amounts of succinate occurs with catal rtic amounts of ATP and CoA, Whiteley postulated a conversion of succinyl-CoA to CO and propionyl-CoA followed by transfer of CoA from propionyl-CoA to succinate (Scheme 3). The transfer of CoA would be catalyzed by an enzyme analogous to Stadtman s CoA transphorase (325), which is present in the bacterial extracts. 

C. propionicum C. butyricum C. barkeri Proteus mirabilis Micrococcus lactilyticus Peptostreptococus anaerobius 4-nitrobenzoate 2-nitroethanol Angermaier and Simon (2)... 

Bacteria can make formate in many ways. A preliminary note by Chin et al. (1957) reports that the phosphoroclastic splitting of pyruvate to HCOOH -h CH3COOH by Escherichia coli was stimulated by FH4. Huen-nekens et al. (1958) refer to similar unpublished results (Whitely, 1958) with Micrococcus aerogenes and M, lactilyticus-, serine was not an intermediate. If the reaction HCOOH H2 + CO2, also carried out by E. coli, turns out to be folic-catalyzed, the presumption would be greatly strengthened that all formate-C02 reactions require FA, as might perhaps also formate-oxalate reactions. 

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