Prions are composed largely, if not entirely, of prion protein (PrPSc in the case scrapie). Although formation PrPSc from cellular (PrPC) is a post-translational process, no candidate chemical modification was identified, suggesting that conformational change features synthesis. To assess this possibility, we purified both PrPC and by using nondenaturing procedures determined secondary structure each. Fourier-transform infrared (FTIR) spectroscopy demonstrated has high alpha-helix content...

By comparing the amino acid sequences of 11 mammalian and 1 avian prion proteins (PrP), structural analyses predicted four alpha-helical regions. Peptides corresponding to these regions Syrian hamster PrP were synthesized, and, contrary predictions, three spontaneously formed amyloids as shown by electron microscopy Congo red staining. IR spectroscopy, amyloid peptides exhibited secondary structures composed largely beta-sheets. The first helices is 14-amino peptide residues 109-122; this...

Limited proteolysis of the scrapie prion protein (PrPSc) generates PrP 27-30, which polymerizes into amyloid. By attenuated total reflection-Fourier transform infrared spectroscopy, 27-30 polymers contained 54% beta-sheet, 25% alpha-helix, 10% turns, and 11% random coil; dispersion detergent-lipid-protein-complexes preserved infectivity secondary structure. Almost 60% beta-sheet was low-frequency infrared-absorbing, reflecting intermolecular aggregation. Decreased increased turn content were...

Abstract By direct explosure of the sample to ion plasma in a chemical ionization source, spectra many relatively involatile compounds can be obtained with temperatures at least 150° below those usually required. A number peptides that have not been derivatized are shown as examples. Determination complete amino acid sequence is possible samples 10 −7 g.

Prion diseases are a group of neurodegenerative disorders in humans and animals that seem to result from conformational change the prion protein (PrP). Utilizing data obtained by circular dichroism infrared spectroscopy, computational studies predicted three-dimensional structure cellular form PrP (PrPc). A heuristic approach consisting prediction secondary structures an evaluation packing elements was used search for plausible tertiary structures. After series experimental theoretical...

Abstract Mass spectra of solutes can be obtained by direct introduction the solution into a chemical ionization source. This should facilitate monitoring effluent from liquid chromatography columns with nanogram sensitivity.

Monitoring of solutes eluted from a liquid chromatograph is possible by continuous introduction the effluent solution into ion source chemical ionization mass spectrometer. Detection sensitivities in nanogram range are for wide variety and solvents. Auxiliary techniques which have proved valuable g.c.-m.s. also appear to be applicable l.c.m.s.

High-energy collision-induced dissociation (CID) mass spectrometry provides a rapid and sensitive means for determining the primary sequence of peptides. The low-mass region (below 300) large number tandem CID spectra peptides has been analyzed. This contains several types informative fragment ions, including dipeptide immonium other related ions. Useful ions are also present in negative-ion spectra. Immonium (general structure [H2N=CH-R](+), where R is amino acid side chain) characteristic...

Conversion of the cellular isoform prion protein (PrPC) into scrapie (PrPSc) involves an increase in beta-sheet content, diminished solubility, and resistance to proteolytic digestion. Transgenetic studies argue that PrPC PrPSc form a complex during formation; thus, synthetic PrP peptides, which mimic conformational pluralism PrP, were mixed with determine whether its properties altered. Peptides encompassing two alpha-helical domains when produced displayed many PrPSc. The PrPC-peptide...

An abnormal isoform of the prion protein (PrP) designated PrPSc is major, or possibly only, component infectious prions. Structural studies have been impeded by its lack solubility under conditions in which infectivity retained. Among many detergents examined, only treatment with ionic detergent sodium dodecyl sulfate (SDS) Sarkosyl followed sonication dispersed rods are composed PrP 27-30, an N-terminally truncated form PrPSc. After ultracentrifugation at 100,000 x g for 1 h, approximately...

• Two surgical approaches were used for nasal and ethmoid cancers involving the anterior skull base. A craniofacial operation with assistance of a neurosurgeon was employed when cribriform plate infiltrated. frontofacial through frontal sinus preferred radiologically intact. Thirty patients underwent radical surgery minimum three-year follow-up. Thirteen 16 adenocarcinoma survived. Since 1980, nine have had their defects repaired revascularized tensor fascia lata muscle skin flap. The flap...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTandem mass spectrometry of higher molecular weight compoundsI. J. Amster, M. A. Baldwin, T. Cheng, C. Proctor, and F. W. McLaffertyCite this: Am. Chem. Soc. 1983, 105, 6, 1654–1655Publication Date (Print):March 1, 1983Publication History Published online1 May 2002Published inissue 1 March 1983https://pubs.acs.org/doi/10.1021/ja00344a040https://doi.org/10.1021/ja00344a040research-articleACS PublicationsRequest reuse permissionsArticle...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRearrangements of toluene and cycloheptatriene cationsM. A. Baldwin, F. W. McLafferty, Donald M. JerinaCite this: J. Am. Chem. Soc. 1975, 97, 21, 6169–6174Publication Date (Print):October 1, 1975Publication History Published online1 May 2002Published inissue 1 October 1975https://pubs.acs.org/doi/10.1021/ja00854a037https://doi.org/10.1021/ja00854a037research-articleACS PublicationsRequest reuse permissionsArticle Views170Altmetric-Citations32LEARN...

The spectra of all the methylated ureas, ethylene urea, and certain alkyl, alkylaryl, aryl ureas are reported discussed. relatively simple, in main can be described terms bond fission to form R1R2N+ or R3R4[graphic omitted]CO 1–3 hydrogen rearrangement [R1R2NH][graphic omitted] [R3NCO][graphic omitted]. There is no evidence for corresponding alkyl rearrangement.

The mass spectra of some alkyl thioureas, alkyl–aryl and aryl thioureas are presented discussed. main primary fragmentation pathways cleavage next to the central carbon atom, with charge residing on either fragment, loss sulphydryl or substituted radicals. differences in behaviour methyl ureas discussed basis a preferred location sulphur but nitrogen ureas. Also, where appropriate, all compounds compared those guanidines. effect chain length groups pattern is using ethyl butyl sensitivity...

Syrian hamster prion protein (PrPC) and a truncated lacking the glycosylphosphatidylinositol (GPI) anchor C-terminal signal sequence (GPI-) were expressed in Chinese ovary cells using glutamine synthetase selection amplification system. The CHO cell clones expressing GPI- PrP secreted majority of into media, whereas most produced by full-length with GPI was located on surface, as demonstrated its release upon treatment phosphatidylinositol-specific phospholipase C (PIPLC). A clone that...

Although no chemical modifications have been found to distinguish the cellular prion protein PrP c from its infectious analogue Sc , spectroscopic methods such as Fourier transform infrared (ftir) spectroscopy reveal a major conformational difference. is rich in a-helix but devoid of β-sheet,whereas high β-sheet. N-terminal truncation by limited proteolysis does not destroy infectivity it increases β-sheet content and shifts ftir absorption lower frequencies, typical cross β-pleated sheets...

This paper reports the unusual collision-induced fragmentation of peptides having N-terminal glutamine. One these glutamine-containing was isolated from an endo-proteinase Lys-C digest scrapie prion protein (PrP 27–30) with predicted sequence QHTVTTTTK. Daughter ion mass spectra show predominant bn and, to a lesser extent, cn series at 17 u less than masses. is interpreted as arising ionic that accompanies peptide-backbone cleavage, glutamine losing ammonia give pyroglutamic acid, reaction...

Abstract The measurement and interpretation of the ionization potentials some (methylated) phosphoramides, acetamides formamides is reported. Additivity rules for prediction are examined.

The mass spectra of crotonosine and some related compounds are reported the composition major fragments determined by high-resolution measurements. Modes fragmentation discussed. In addition model compound tetrahydroisoquinoline its N-methyl N-acetyl derivatives