34450-18-5Relevant articles and documents
Preparation method of long-chain diacid
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Paragraph 0050-0051; 0054-0056; 0080; 0084-0086, (2021/11/03)
The invention provides a preparation method of long-chain diacid, which comprises the following steps of: (S1) carrying out an addition reaction on olefine acid or an ester derivative thereof serving as a raw material and liquid bromine to obtain dibromo carboxylic acid or an ester derivative thereof; (S2) carrying out an elimination reaction on the dibromo carboxylic acid or ester derivative thereof under the action of sodium amide to obtain alkynyl-terminated carboxylic acid or an ester derivative thereof; (S3) carrying out an addition reaction on the alkynyl-terminated carboxylic acid or the ester derivative thereof and diborane to obtain borane or boric acid containing carboxyl or ester group; and (S4) oxidizing the borane or boric acid to obtain long-chain diacid. According to the invention, olefine acid is used as a raw material, is easily available in source and low in price, so that the production cost of the product is very low; and meanwhile, the raw materials used in the synthesis process do not contain precious metals or other expensive reagents, so that the synthesis process is suitable for industrial amplification production, and the defect that the method in the prior art is not environment-friendly, not suitable for industrial production and high in preparation cost is overcome.
Synthetic Fluorogenic Peptides Reveal Dynamic Substrate Specificity of Depalmitoylases
Amara, Neri,Foe, Ian T.,Onguka, Ouma,Garland, Megan,Bogyo, Matthew
, p. 35 - 7,47 (2018/10/24)
Palmitoylation is a post-translational modification involving the thioesterification of cysteine residues with a 16-carbon-saturated fatty acid. Little is known about rates of depalmitoylation or the parameters that dictate these rates. Here we report a modular strategy to synthesize quenched fluorogenic substrates for the specific detection of depalmitoylase activity and for mapping the substrate specificity of individual depalmitoylases. We demonstrate that human depalmitoylases APT1 and APT2, and TgPPT1 from the parasite Toxoplasma gondii, have distinct specificities that depend on amino acid residues distal to the palmitoyl cysteine. This information informs the design of optimal and non-optimal substrates as well as isoform-selective substrates to detect the activity of a specific depalmitoylase in complex proteomes. In addition to providing tools for studying depalmitoylases, our findings identify a previously unrecognized mechanism for regulating steady-state levels of distinct palmitoylation sites by sequence-dependent control of depalmitoylation rates. Amara et al. describe a method for preparing positional scanning libraries of fluorogenic palmitoylated peptide substrates. This allowed identification of residues that are distal to the palmitoylation site that impact turnover. This information allowed the design of substrates that are selective for a specific depalmitoylating enzyme.
Synthesis and thermotropic properties of macrocyclic lipids related to archaebacterial membranes
Menger,Chen,Brocchini,Hopkins,Hamilton
, p. 6600 - 6608 (2007/10/02)
Macrocyclic phospholipids containing 32-44 ring atoms were synthesized by a route involving a high-temperature Glaser oxidation as the key step. These lipids are analogous to mammalian phospholipids except a single extra carboncarbon bond joins the chain termini. The new lipids offered, therefore, an opportunity to examine thermotropic properties of their membranes when the chains within a given molecule are unable to move independently of one another. It was concluded that chain "tethering" (a) raises the transition temperatures substantially for all but the shortest lipids, (b) lowers enthalpies of transition by, in part, reducing the number of gauche C-C linkages created during the melting process, and (c) lowers entropies of transition by impeding motional freedom within the liquid-crystalline phase. Molecular mechanics calculations on the macrocyclic lipids are described briefly.