FEATURED MACHINE 10 / 12

Hydrogenase

Makes electrons from hydrogen available to metabolism.

LIBRARY BASIS · BACTERIAL ACCOUNT

The question behind this machine

The closest verified library match is broader metal-cluster synthesis. The hydrogenase-specific explanation is developed from primary work, supported by bacterial structural and maturation experiments; the broader thread supplies related cofactor context.^L1

Catalysis with a built-in metal centre

The Desulfovibrio gigas structure established the organization of a bacterial nickel–iron hydrogenase, including its metal-containing catalytic region and iron–sulfur electron-transfer components. The relevant distinction is between a correctly folded protein scaffold and a mature redox enzyme containing the appropriate inorganic centres.^P1

Maturation is another layer of the problem

A bacterial maturation study isolated a HypC–HypD complex carrying CO and cyanide ligands associated with [NiFe]-centre construction. This demonstrates that accessory-protein chemistry can be investigated separately from the final enzyme’s hydrogen-conversion activity. The experiment does not establish that every organism uses an identical maturation sequence.^P2

Precision in coordination chemistry

The chemically important questions concern metal identity, ligand arrangement, access of substrates and transfer of electrons to appropriate partners. These are more specific than requiring an arbitrary metal aggregate near a protein. Exact ligand geometry and oxygen sensitivity must be established for the particular hydrogenase; the atlas does not assign one universal hydrogenase specification.

Activity, protection and the historical target

An assay should distinguish inactive apoprotein, failed cofactor maturation, damaged redox centres and a catalytic state that can be reactivated. For origin arguments, compare mineral or small-molecule catalysis with a maintained, selective biological electron-transfer system. Demonstrating hydrogen chemistry alone addresses only part of the transition to a cellular energy network.

Connected to the rest of the cell

This machine depends on resources and supporting systems, and its work supplies other cellular processes.

FUNCTIONAL ORGANIZATION · AUTHOR’S FRAMEWORK

Hallmarks of design

Hydrogenase illustrates the following organizational features in the supplied papers. These descriptions identify biological functions; interpreting their origin as design is the author’s comparative argument.^{H1, H2}

H25Cofactor dependency networks

An appropriate metal active centre requires maturation machinery.

H27Material selection

Activity depends on particular molecular identities and coordination chemistry.

H24Metabolic integration

Hydrogen oxidation supplies electrons that connect to energy metabolism.

Origin hurdles and abductive assessment · Assessment method · All 40 hallmarks. Biological evidence: the mechanism, accession records and scientific references on this page.

Origins and explanatory assessment

INFERENCE TO THE BEST EXPLANATION · PROVISIONAL ASSESSMENT

From origin hurdles to a cautious inference

What needs explaining. Explain compatible metal-centre chemistry, maturation and electron transfer in a plausible environment, considering simpler catalysts and related enzyme families.

Positive observations. An appropriate metal active centre requires maturation machinery. Activity depends on particular molecular identities and coordination chemistry.

Compare the explanations. The design proposal appeals to coordinated functional organization, not complexity alone. A natural account can include chemical affinities, self-assembly, co-option, duplication, common ancestry and selection where heredity exists; it need not draw a complete modern system in one random trial. Present operation, historical emergence and first-cell origins are separate questions.

Abductive conclusion. The coordinated features give the author a positive reason to consider design within the wider cellular architecture. For this local system alone, they do not establish that design is uniquely the best historical explanation. The conservative inference is that the system contributes to a cumulative design case, with its weight conditional on the comparative evidence and on how much plausible natural pathways explain.

What could change the assessment. Functional intermediates, sequence-family relationships and experimentally connected steps would strengthen a natural account in proportion to what they explain. Loss of a claimed dependency or discovery of functional alternatives would weaken the corresponding design argument. Gaps in the record do not supply a numerical likelihood for either explanation.

Method, assumptions and revision criteria^{H1, H2}. Evaluate alongside the origin discussion and scientific sources on this page.

Represented in the 912-protein inventory

2 selected protein entries. These entries identify selected components represented in the working inventory; they do not establish the complete composition or copy numbers of an assembled machine.

Gene / locus	Protein entry	Source record
mbhS1aq_660	Hydrogenase small subunit	O66894 ↗
mbhL1aq_662	Hydrogenase large subunit	O66895 ↗

Follow the evidence

Each source-record link opens its UniProt entry. Gene links open the corresponding entry in this atlas’s working inventory.

Related scientific references ↗

Sources for the developed article

Library essays and topic discussions

L1. Otangelo Grasso, Iron-sulfur clusters: Basic building blocks for life . Broader cofactor context.

Primary scientific evidence

P1. Volbeda et al. (1995), Crystal structure of the nickel-iron hydrogenase from Desulfovibrio gigas.
P2. Soboh et al. (2012), [NiFe]-hydrogenase maturation: isolation of a HypC-HypD complex carrying diatomic CO and CN− ligands.

Numbered protein records establish the selected inventory entries; these experimental examples establish the mechanisms identified above. Results from another bacterial species are not automatically Aquifex-specific measurements. Explore the library-to-atlas source guide →