CN− secondary ions form by recombination as demonstrated using multi-isotope mass spectrometry of 13C- and 15N-labeled polyglycine

McMahon, Greg; Saint-Cyr, Hugues François; Lechène, C.; Ünkefer, Clifford J.

doi:10.1016/j.jasms.2006.04.031

Cited by 36 publications

(52 citation statements)

References 8 publications

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“…HeLa cells were starved of all amino acids for 15 min, and then incubated for 2 min in both [ 13 C]amino acids and [ 15 N]amino acids (each set being uniformly-labeled with the respective heavy atom). Protein synthesis will covalently link some 13 C atoms with 15 N atoms; this should then yield (heavy-heavy) 13 C 15 N − ions during NanoSIMS [29] ( Fig. 3C i ).…”

Section: Resultsmentioning

confidence: 99%

Most Human Proteins Made in Both Nucleus and Cytoplasm Turn Over within Minutes

et al. 2014

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In bacteria, protein synthesis can be coupled to transcription, but in eukaryotes it is believed to occur solely in the cytoplasm. Using pulses as short as 5 s, we find that three analogues – L-azidohomoalanine, puromycin (detected after attaching fluors using ‘click’ chemistry or immuno-labeling), and amino acids tagged with ‘heavy’ 15N and 13C (detected using secondary ion mass spectrometry) – are incorporated into the nucleus and cytoplasm in a process sensitive to translational inhibitors. The nuclear incorporation represents a significant fraction of the total, and labels in both compartments have half-lives of less than a minute; results are consistent with most newly-made peptides being destroyed soon after they are made. As nascent RNA bearing a premature termination codon (detected by fluorescence in situ hybridization) is also eliminated by a mechanism sensitive to a translational inhibitor, the nuclear turnover of peptides is probably a by-product of proof-reading the RNA for stop codons (a process known as nonsense-mediated decay). We speculate that the apparently-wasteful turnover of this previously-hidden (‘dark-matter’) world of peptide is involved in regulating protein production.

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Section: Resultsmentioning

confidence: 99%

Most Human Proteins Made in Both Nucleus and Cytoplasm Turn Over within Minutes

et al. 2014

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“…This might be due to the adsorption of N 2 onto the sample surface despite high vacuum. N monoatoms coming from the beam-induced breaking of adsorbed N 2 may participate to nonorganic CN À ions formation [31]. In any case, the present data highlight the need to use at least two standards to build such a calibration line in order to precisely and accurately (±0.009-95% confidence level) estimate N/C values of unknown carbon samples.…”

Section: Nanosims Estimation Of N/c Ratiosmentioning

confidence: 75%

Estimation of nitrogen-to-carbon ratios of organics and carbon materials at the submicrometer scale

Alleon

Bernard

Rémusat

et al. 2015

Carbon

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International audiencePrecisely estimating nitrogen-to-carbon (N/C) ratio of carbonaceous materials at the submicrometer scale is a challenge in both natural and material sciences. Following recent attempts reported in the literature, the present paper discusses two methods of quantification of the N/C ratio or organics and carbon materials at the submicrometer scale using nanoscale secondary ion mass spectrometry (NanoSIMS) and X-ray absorption spectroscopy (XAS). The present data highlight the need to use at least two standards to build a calibration line in order to precisely and accurately (± 0.009 – 95 % confidence level) estimate N/C values of unknown carbon samples using NanoSIMS. As shown here using a set of reference compounds, STXM-based XAS allows directly estimating N/C ratios of organics without using any standard with errors as low as 0.007

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“…Ion images of these large grains suggest they are relatively rich in C and depleted in N compared to the other material. In contrast, we also identify patches of material with higher N emission (N is detected as molecular CN À ions; McMahon et al, 2006), but for sake of clarity, we will Fig. 6.…”

Section: Elemental Compositions From Nanosims Imagingmentioning

confidence: 99%