Lipid mapping in human dystrophic muscle by cluster-time-of-flight secondary ion mass spectrometry imaging.

Human striated muscle samples, from male control and Duchenne muscular dystrophy-affected children, were subjected to cluster-time-of-flight secondary ion mass spectrometry (cluster-ToF-SIMS) imaging using a 25 keV Bi(3)(+) liquid metal ion gun under static SIMS conditions. Spectra and ion density maps, or secondary ion images, were acquired in both positive and negative ion mode over several areas of 500 x 500 microm(2) (image resolution, 256 x 256 pixels). Characteristic distributions of various lipids were observed.

Coenzyme binding during catalysis is beneficial for the stability of 4-hydroxyacetophenone monooxygenase.

The NADPH-dependent dimeric flavoenzyme 4-hydroxyacetophenone monooxygenase (HAPMO) catalyzes Baeyer-Villiger oxidations of a wide range of ketones, thereby generating esters or lactones. In the current work, we probed HAPMO-coenzyme complexes present during the enzyme catalytic cycle with the aim to gain mechanistic insight. Moreover, we investigated the structural role of the nicotinamide coenzyme.

Cofactor-dependent assembly of the flavoenzyme vanillyl-alcohol oxidase.

The oligomerization of the flavoprotein vanillyl-alcohol oxidase (VAO) and its site-directed mutant H61T was studied by mass spectrometry. Native VAO has a covalently bound FAD and forms primarily octameric assemblies of 507 kDa. H61T is purified as a FAD-free apoprotein and mainly exists as a dimeric species of 126 kDa.

A covalent modification of NADP+ revealed by the atomic resolution structure of FprA, a Mycobacterium tuberculosis oxidoreductase.

FprA is a mycobacterial oxidoreductase that catalyzes the transfer of reducing equivalents from NADPH to a protein acceptor. We determined the atomic resolution structure of FprA in the oxidized (1.05 A resolution) and NADPH-reduced (1.