Acyl Transfer (acyl + transfer)

Distribution by Scientific Domains

Selected Abstracts

Synthesis and use of a pseudo-cysteine for native chemical ligation

David A. Alves
Abstract The process of native chemical ligation (NCL) is well described in the literature. An N -terminal cysteine-containing peptide reacts with a C -terminal thioester-containing peptide to yield a native amide bond after transesterification and acyl transfer. An N -terminal cysteine is required as both the N -terminal amino function and the sidechain thiol participate in the ligation reaction. In certain circumstances it is desirable, or even imperative, that the N -terminal region of a peptidic reaction partner remain unmodified, for instance for the retention of biological activity after ligation. This work discusses the synthesis of a pseudo- N -terminal cysteine building block for incorporation into peptides using standard methods of solid phase synthesis. Upon deprotection, this building block affords a de factoN -terminal cysteine positioned on an amino acid sidechain, which is capable of undergoing native chemical ligation with a thioester. The syntheses of several peptides and structures containing this motif are detailed, their reactions discussed, and further applications of this technology proposed. Copyright 2003 European Peptide Society and John Wiley & Sons, Ltd. [source]

Reactivity and structure of derivatives of 2-hydroxy-1,4-naphthoquinone (lawsone),

G. Lamoureux
Abstract The structures of two derivatives of 2-hydroxy-1,4-naphthoquinone (lawsone) are examined using the density functional theory (DFT) hybrid functional B3LYP. Using the optimized structure of lawsone acetate, the reactivity of acyl transfer is described. Also, the nucleophilicity of the conjugate base of lawsone is predicted using the conceptual descriptors related to softness within the DFT framework. Copyright 2008 John Wiley & Sons, Ltd. [source]

Identification and characterization of a novel anthocyanin malonyltransferase from scarlet sage (Salvia splendens) flowers: an enzyme that is phylogenetically separated from other anthocyanin acyltransferases

Hirokazu Suzuki
Summary Anthocyanin acyltransferases (AATs) catalyze a regiospecific acyl transfer from acyl-CoA to the glycosyl moiety of anthocyanins, thus playing an important role in flower coloration. The known AATs are subfamily members of an acyltransferase family, the BAHD family, which play important roles in secondary metabolism in plants. Here, we describe the purification, characterization, and cDNA cloning of a novel anthocyanin malonyltransferase from scarlet sage (Salvia splendens) flowers. The purified enzyme (hereafter referred to as Ss5MaT2) is a monomeric 46-kDa protein that catalyzes the transfer of the malonyl group from malonyl-CoA to the 4,,,-hydroxyl group of the 5-glucosyl moiety of anthocyanins. Thus, it is a malonyl-CoA:anthocyanin 5-glucoside 4,,,- O -malonyltransferase. On the basis of the partial amino acid sequences of the purified enzyme, we isolated a cDNA that encodes an acyltransferase protein. The steady-state transcript level of the gene was the highest in recently opened, fully pigmented flowers and was also correlated with the trend observed for an AAT gene responsible for the first malonylation step during salvianin biosynthesis. Immunoprecipitation studies using antibodies against the recombinant acyltransferase protein corroborated the identity of this cDNA as that encoding Ss5MaT2. The deduced amino acid sequence of Ss5MaT2 showed a low similarity (22,24% identity) to those of AATs and lacked the AAT-specific signature sequence. A phylogenetic analysis suggested that Ss5MaT2 is more related to acetyl-CoA:benzylalcohol acetyltransferase (BEAT) rather than to AAT. This is another example in which enzymes with similar, although not identical, substrate evolved from different branches of the BAHD family. [source]

Dissection of Two Acyl-Transfer Reactions Centered on Acyl-S-Carrier Protein Intermediates for Incorporating 5-Chloro-6-methyl- O -methylsalicyclic Acid into Chlorothricin

CHEMBIOCHEM, Issue 5 2009
Qing-Li He Dr.
Abstract Making the microbes work for us: An acyl-carrier-protein-centered strategy that involves two distinct acyl-transfer steps for generation and regiospecific attachment of the 5-chloro-6-methyl- O -methylsalicyl group onto the C3, position of D -olivose was elucidated in the biosynthetic pathway of chlorothricin. Identification of the mutant of the acyltransferase-associated intermediate validated the critical role of the highly conserved Cys residue, which channels the acyl transfer by using its thiolate side chain as a nucleophile in a two-step process. [source]