Word frequency plays a role in reduction processes: high-frequency words undergo more reduction than low-frequency words. Pretonic schwa reduction in Dutch is susceptible to frequency effects in this way, but the well-formedness of the cluster that remains after schwa deletion also plays a role. An experiment shows that cluster well-formedness and frequency effects in fact interact with each ot...

In nitrogen fixation by Azotobacter vinelandii nitrogenase, the iron protein (FeP) binds to and subsequently transfers electrons to the molybdenum-FeP, which contains the nitrogen fixation site, along with hydrolysis of two ATPs. However, the nature of the reduced state cluster is not completely clear. While reduced FeP is generally thought to contain an [Fe4 S4 ](1+) cluster, evidence also exi...

Heterodisulfide reductase (HDR) from methanogenic archaea is an iron-sulfur protein that catalyzes reversible reduction of the heterodisulfide (CoM-S-S-CoB) of the methanogenic thiol-coenzymes, coenzyme M (CoM-SH) and coenzyme B (CoB-SH). Via the characterization of a paramagnetic reaction intermediate generated upon oxidation of the enzyme in the presence of coenzyme M, the enzyme was shown to...

This paper proposes a new representation space, called the cluster space, for data points that originate from high dimensions. Whereas existing dedicated methods concentrate on revealing manifolds from within the data, we consider here the context of clustered data and derive the dimension reduction process from cluster information. Points are represented in the cluster space by means of their ...

The recently discovered methylerythritol phosphate (MEP) pathway provides new targets for the development of antibacterial and antimalarial drugs. In the final step of the MEP pathway, the [4Fe-4S] IspH protein catalyzes the 2e(-)/2H(+) reductive dehydroxylation of (E)-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) to afford the isoprenoid precursors isopentenyl pyrophosphate (IPP) and dimet...