Structure and mutational analysis of a plant mitochondrial nucleoside diphosphate kinase. Identification of residues involved in serine phosphorylation and oligomerization.

We report the first crystal structure of a plant (Pisum sativum L. cv Oregon sugarpod) mitochondrial nucleoside diphosphate kinase. Similar to other eukaryotic nucleoside diphosphate kinases, the plant enzyme is a hexamer; the six monomers in the asymmetric unit are arranged as trimers of dimers.

Conformational flexibility of the C terminus with implications for substrate binding and catalysis revealed in a new crystal form of deacetoxycephalosporin C synthase.

Deacetoxycephalosporin C synthase (DAOCS) from Streptomyces clavuligerus catalyses the oxidative ring expansion of the penicillin nucleus into the nucleus of cephalosporins. The reaction requires dioxygen and 2-oxoglutarate as co-substrates to create a reactive iron-oxygen intermediate from a ferrous iron in the active site. The active enzyme is monomeric in solution.