NAD-linked hydrogenase

Hornhardt, S., Schneider, K., Friedrich, B., Vogt, B. and Schlegel, H. G. (1990) Identification of distinct NAD-linked hydrogenase protein species in mutants and nickel-deficient wild-type cells of Alcaligenes eutrophus H16. Eur. J. Biochem., 189, 529-37. 

Fig. 11. Dissociation and reassociation of soluble, NAD-linked hydrogenase from Nocardia opaca. Diaphorase refers to NADH acceptor reductase activity. Reproduced, with permission, from Ref. 82.

Such a metabolism ( fumarate respiration ) is well known from anaerobic mitochondria (Tielens et al. 2002 Tielens and van Hellemond, Chap. 6 in this volume), but is unique in combination with a hydrogenase that might compete with the fumarate reductase for the same substrates. This hydrogenase of N. ovalis represents a novel type of [Fe]-only or [FeFe]-hydrogenase that allows H2 formation to be coupled directly to the reoxidation of NADH. The [Fe]-hydrogenase is linked covalently with a protein, which possesses NAD and FMN binding sites, and a ferredoxin-like FeS module that allows transfer... 

Some hydrogenases are membrane-bound, and they are often linked to formate dehydrogenase (HCOOH + NAD COj-l-NADH-rH NADH + H NAD + H2). In strictly anaerobic bacteria, hydrogenases are linked to ferredoxin, and they catalyse an oxidoreduction reaction between hydrogen and ferredoxin H2 + 2Fd, -y 2H + 2Fd j, where Fd ,... 

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