Desulfomicrobium baculatum

In the structure of the [NiFeSe] enzyme from Desulfomicrobium baculatum, one of the four cysteines involved in Ni coordination, one sulfur cysteine is replaced by a selenocysteine (Scheme 77b).409 419... 

Desulfomicrobium baculatum D. baculatum formerly Desulfovibrio desulfurican strain Norway 4... 

It has also been shown that in some microorganisms, such as Desulfomicrobium baculatum, a cycteine-S has been replaced by a cysteine-SE [24], giving rise to a trinudear [FeNiSe] hydrogenase. 

Fig. 1. The X-ray structure for the reduced form of the NiFe dimer in hydro-genase from Desulfomicrobium baculatum.

A cytochrome containing eight hemes has been isolated from D. gigas [67], Desulfomicrobium baculatum Norway 4 [68] and Desulfovibrio africanus [69]. It has been named as the cytochrome c3 (Mr 26,000) because of its molecular mass of 26 kDa, but was previously known as cytochrome cc3. It was shown to be composed of two identical 4-heme subunits of 13,500 Da, both in Dsm. baculatum Norway 4 [70], and in D. gigas [71]. In this last case the two subunits are linked by two disulfide bridges. 

Desulforubidin was purified from Desulfomicrobium baculatum Norway 4 [120] and DSM 1743 [113], and recently from Desulfosarcina variabilis [119]. This type of sulfite reductase is characterized by an absorption peak at 545 nm. Their molecular mass and subunit structure are very similar to that of de-sulfoviridins, and a y subunit has also been observed [119,121]. In contrast to desulfoviridin, the sirohemes are fully metallated. 

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