Linked Life Data

1564721

Source:http://linkedlifedata.com/resource/pubmed/id/1564721

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 2
pubmed:dateCreated
1992-5-18
pubmed:abstractText
The combination of scanning transmission electron microscopy (STEM) and parallel-detection energy-loss spectroscopy (EELS) was used to detect specific bound elements within macromolecules and macromolecular assemblies prepared by direct freezing. After cryotransferring and freeze-drying in situ, samples were re-cooled to liquid nitrogen temperature and low-dose (about 10(3) e/nm2) digital dark-field images were obtained with single-electron sensitivity using a beam energy of approximately 100 keV and a probe current of approximately 5 pA. These maps provided a means of characterizing the molecular weights of the structures at low dose. The probe current was subsequently increased to about 5 nA in order to perform elemental analysis. The 320 copper atoms in a keyhole limpet haemocyanin molecule (mol.wt = 8 MDa) were detected with a sensitivity of +/- 30 atoms in an acquisition time of 200 s. Phosphorus was detected in an approximately 10-nm length of single-stranded RNA contained in a tobacco mosaic virus particle (mol.wt = 130 kDa/nm) with a sensitivity of +/- 25 atoms. Near single-atom sensitivity was achieved for the detection of iron in one haemoglobin molecule (mol.wt = 65 kDa, containing four Fe atoms). Such detection limits are only feasible if special processing methods are employed, as is demonstrated by the use of the second-difference acquisition technique and multiple least-squares fitting of reference spectra. Moreover, an extremely high electron dose (about 10(10) e/nm2) is required resulting in mass loss that may be attributable to 'knock-on' radiation damage.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-2720
pubmed:author
pubmed:issnType
Print
pubmed:volume
165
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
225-38
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Characterization of biological macromolecules by combined mass mapping and electron energy-loss spectroscopy.
pubmed:affiliation
Biomedical Engineering and Instrumentation Program, NCRR, National Institutes of Health, Bethesda, MD 20892.
pubmed:publicationType
Journal Article