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N-terminal Acetylation (n-terminal + acetylation)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Post-translational modifications, but not transcriptional regulation, of major chloroplast RNA-binding proteins are related to Arabidopsis seedling development

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2006
Bai-Chen Wang
Abstract Chloroplast RNA-binding proteins are involved in stabilizing stored chloroplast mRNAs and in recruiting site-specific factors that mediate RNA metabolism. In the present study, we characterized two major chloroplast RNA-binding proteins, cp29A and cp29B, by MALDI-TOF MS, N-terminal sequencing, and ESI-MS/MS following 2D-PAGE separation. Polypeptides derived from cp29A were recovered with free N-terminus or with N-terminal acetylation. In addition to the two isoforms found for cp29A, an isoform derived from cp29B was also observed to have five amino acids cleaved from its N-terminus. Results of quantitative real-time RT-PCR indicate that both genes reached maximal rates of transcription 96,h after commencement of germination and maintained relatively high levels throughout the whole life cycle. Transcription of cp29A and cp29B did not vary significantly under light or dark conditions, although production of the acetylated and N-terminally cleaved protein isoforms exhibited light dependence. Exposure of etiolated Arabidopsis seedlings to light conditions for as short as 9,h restored the modified isoforms to levels similar to those found in green plants. Identification of post-translational modifications in major chloroplast RNA-binding proteins may help elucidate their roles in seedling development and in plant RNA stabilization during the greening process. [source]

Proteome analysis of human foetal, aged and advanced nuclear cataract lenses

PROTEOMICS - CLINICAL APPLICATIONS, Issue 12 2008
Peter G. Hains
Abstract The most complete proteome of human lenses has been compiled using 2-D LC-MS/MS analysis of foetal, aged normal and advanced nuclear cataract lenses. A total of 231 proteins were identified across all lens groups, including 112 proteins that have not been reported previously. Proteins were grouped according to their PANTHER molecular function classification in order to facilitate comparisons. Previously unreported N-terminal acetylation was detected in a number of proteins, with the majority being associated with the prior removal of a methionine residue. This pattern of proteolysis may indicate that methionine aminopeptidase activity is present in human lenses. Acetylation is likely to aid in the stability of proteins that are present in the lens for many decades. Protein sequences were also used to interrogate the three human lens cDNA libraries publicly available. Surprisingly, 84 proteins we identified were not present in the cDNA libraries. [source]

Identification of N-terminal acetylation in Hb Raleigh (,1Val,Ac-Ala) by electrospray tandem mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2002
Dilip K. Rai
First page of article [source]

Copper binding to octarepeat peptides of the prion protein monitored by mass spectrometry

PROTEIN SCIENCE, Issue 2 2000
Randy M. Whittal
Abstract Electrospray ionization mass spectrometry (ESI-MS) was used to measure the binding of Cu2+ ions to synthetic peptides corresponding to sections of the sequence of the mature prion protein (PrP). ESI-MS demonstrates that Cu2+ is unique among divalent metal ions in binding to PrP and defines the location of the major Cu2+ binding site as the octarepeat region in the N-terminal domain, containing multiple copies of the repeat ProHisGlyGlyGlyTrpGlyGln. The stoichiometries of the complexes measured directly by ESI-MS are pH dependent: a peptide containing four octarepeats chelates two Cu2+ ions at pH 6 but four at pH 7.4. At the higher pH, the binding of multiple Cu2+ ions occurs with a high degree of cooperativity for peptides C-terminally extended to incorporate a fifth histidine. Dissociation constants for each Cu2+ ion binding to the octarepeat peptides, reported here for the first time, are mostly in the low micromolar range; for the addition of the third and fourth Cu2+ ions to the extended peptides at pH 7.4, KD's are <100 nm. n-terminal acetylation of the peptides caused some reduction in the stoichiometry of binding at both ph's. cu2+ also binds to a peptide corresponding to the extreme N-terminus of PrP that precedes the octarepeats, arguing that this region of the sequence may also make a contribution to the Cu2+ complexation. Although the structure of the four-octarepeat peptide is not affected by pH changes in the absence of Cu2+, as judged by circular dichroism, Cu2+ binding induces a modest change at pH 6 and a major structural perturbation at pH 7.4. It is possible that PrP functions as a Cu2+ transporter by binding Cu2+ ions from the extracellular medium under physiologic conditions and then releasing some or all of this metal upon exposure to acidic pH in endosomes or secondary lysosomes. [source]