A review of COFRADIC techniques targeting protein N-terminal acetylation

Acetylation of nascent protein Nalpha-termini is a common modification among archae and eukaryotes and can influence the structure and function of target proteins. This modification has been studied on an individual protein or (synthetic) peptide level or on a proteome scale using two-dimensional polyacrylamide gel electrophoresis. We recently developed mass spectrometry driven proteome analytical approaches specifically targeting the amino (N) terminus of proteins based on the concept of diagonal reverse-phase chromatography. We here review how this so-called combined fractional diagonal chromatography (COFRADIC) technique can be used in combination with differential mass-tagging strategies as to both qualitatively and quantitatively assess protein Nalpha-acetylation in whole proteomes

Integrated approaches to restore gullies in land prone to soil piping : innovations from the drylands of northern Ethiopia

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The covalent structure of Acanthamoeba actobindin

Actobindin is a protein from Acanthamoeba castellanii with bivalent affinity for monomeric actin. Because it can bind two molecules of actin, actobindin is a substantially more potent inhibitor of the early phase of actin polymerization than of F-actin elongation. The complete amino acid sequence of 88 residues has been deduced from the determined sequences of overlapping peptides obtained by cleavage with trypsin, Staphylococcus V8 protease, endoproteinase Asp-N, and CNBr. Actobindin contains 2 trimethyllysine residues and an acetylated NH2 terminus. About 76% of the actobindin molecule consists of two nearly identical repeated segments of approximately 33 residues each. This could explain actobindin's bivalent affinity for actin. The circular dichroism spectrum of actobindin is consistent with 15% alpha-helix and 22% beta-sheet structure. A hexapeptide with sequence LKHAET, which occurs at the beginning of each of the repeated segments of actobindin, is very similar to sequences found in tropomyosin, muscle myosin heavy chain, paramyosin, and Dictyostelium alpha-actinin. A longer stretch in each repeated segment is similar to sequences in mammalian and amoeba profilins. Interestingly, the sequences around the trimethyllysine residues in each of the repeats are similar to the sequences flanking the trimethyllysine residue of rabbit reticulocyte elongation factor 1 alpha, but not to the sequences around the trimethyllysine residues in Acanthamoeba actin and Acanthamoeba profilins I and II