S-acylation is a major posttranslational modification, catalyzed by the zinc finger DHHC domain containing (zDHHC) enzyme family. S-acylated proteins can be modified by different fatty acids; however, very little is known about how zDHHC enzymes contribute to acyl chain heterogeneity. Here, we used fatty acid-azide/alkyne labeling of mammalian cells, showing their transformation into acyl-CoAs and subsequent click chemistry-based detection, to demonstrate that zDHHC enzymes have marked differences in their fatty acid selectivity. This difference in selectivity was apparent even for highly related enzymes, such as zDHHC3 and zDHHC7, which displayed a marked difference in their ability to use C18:0 acyl-CoA as a substrate. Furthermore, we identified isoleucine-182 in transmembrane domain 3 of zDHHC3 as a key determinant in limiting the use of longer chain acyl-CoAs by this enzyme. This study uncovered differences in the fatty acid selectivity profiles of cellular zDHHC enzymes and mapped molecular determinants governing this selectivity.-acylation is a reversible posttranslational modification (PTM) involving the attachment of fatty acids onto cysteines (1, 2). This PTM occurs on both soluble and transmembrane (TM) proteins and exerts a number of important effects, including mediating membrane binding (of soluble proteins or soluble loops of TM proteins), regulating protein trafficking and targeting to cholesterol-rich membrane microdomains, and modulating protein stability (3, 4). These actions of S-acylation on a diverse array of cellular proteins affect many important physiological pathways, and defects in this process are linked to a number of major diseases and disorders (2, 5).S-acylation is mediated by the opposing actions of acyltransferases and thioesterases. S-acyltransferase enzymes belong to the zinc finger DHHC domain containing (zDHHC) protein family, which are encoded by 24 distinct genes (6-8). zDHHC enzymes are thought to share the same overall membrane topology, with four to six transmembrane domains and the N and C termini present in the cytosol (9). The catalytic DHHC cysteinerich domain (CRD) of the enzymes lies in a cytosolic loop (9), allowing zDHHC enzymes to modify substrate cysteines present at the cytosol-membrane interface. The S-acylation reaction is thought to proceed through an enzyme-acyl intermediate, where the acyl chain is attached to the cysteine of the DHHC motif via a thioester linkage (often referred to as enzyme "autoacylation") (10, 11). The S-acyl chain is then transferred to a cysteine residue of a substrate protein (10,11). This overall process is referred to as a "ping-pong" reaction mechanism. There has been progress in identifying the zDHHC enzymes that are active against many substrate proteins (2), although we lack a detailed understanding of the protein substrate profiles of individual enzymes and how enzyme-substrate interaction specificity is achieved. Coexpression experiments have suggested that individual zDHHC enzymes might exhibit a level of overlap in their ...

Malonoyl peroxide 1, prepared in a single step from the commercially available diacid, is an effective reagent for the anti-dihydroxylation of alkenes. Reaction of 1 with an alkene in the presence of acetic acid at 40 °C followed by alkaline hydrolysis leads to the corresponding diol (35-92%) with up to 13:1 anti-selectivity. A mechanism consistent with experimental findings is proposed that accounts for the selectivity observed.

Treatment of homoallylic N-tosyl amines or allylic N-tosyl hydroxylamines with 1.5 equiv of a malonoyl peroxide provides a stereoselective method to access functionalized pyrrolidines and isoxazolidines. This metal free alkene oxyamination proceeds in 50-85% yield and up to 13:1 trans-selectivity. In addition, the relative stereochemistry of the oxygen and nitrogen substituents can be inverted through an oxidation/reduction sequence or inverting the stereochemistry of the starting alkene. Mechanistic investigations show a higher reactivity for hydroxyl nucleophiles over sulfonamide nucleophiles revealing a preference for dioxygenation over oxyamination.

Treatment of a sulfide with a catalytic amount of a 1,3-diketone in the presence of silica sulfuric acid as a co-catalyst and hydrogen peroxide (50% aq) as the stoichiometric oxidant leads to the corresponding sulfoxide product. The reaction is effective for diaryl, aryl-alkyl and dialkyl sulfides and is tolerant of oxidisable and acid sensitive functional groups.Investigations have shown that the tris-peroxide 2, formed on reaction of pentane-2,4-dione with hydrogen peroxide under acidic reaction conditions, can oxidise two equivalents of sulfide using the exocyclic peroxide groups whereas the endocyclic peroxide remains intact.Calculations provide a mechanism consistent with experimental observations and suggest the reaction proceeds via an initial acid catalysed ring opening of a protonated tris-peroxide prior to oxygen transfer to a sulfur nucleophile.

VIDEEO which is an acronym of VIrtual Development Enterprise for EurOpe is a web-based environment which supports both students and tutors in the creation and execution of multidisciplinary, distributed, product development projects. One of the main aims of VIDEEO is to provide a teaching and learning environment which provides an appropriate balance between technical and vocational study. The VIDEEO project was funded by SOCRATES and was completed by a team of partners from eight european institutions. The objective of this paper is to provide an overview of the lifecycle of the VIDEEO project from development through to evaluation and usage.