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M M Cordero

Publications and source records attributed to M M Cordero.

6 recordsLinked to original sources
PubMed1995

Sequencing electroblotted proteins by tandem mass spectrometry.

Electroblotting proteins separated by gel electrophoresis provides a suitable support for further manipulations and analysis of small amounts of relatively pure samples. On-membrane digestion, peptide mapping by mass spectrometry, and database searching offer sensitive and fast tools to identify the analyte. By providing sequence information, tandem mass spectrometry can go a step further, confirming the database identification, solving problems connected with post-translational modifications and sequence variations, or supplying the stretches of internal sequence necessary to synthesize an oligonucleotide probe for gene isolation. The viability of this approach was successfully evaluated using different tandem mass spectrometric techniques: metastable decomposition in a matrix-assisted laser desorption/ionization (MALDI) time-of-flight instrument with a curved-field reflectron; low energy collision-induced dissociation in a MALDI quadrupole ion trap mass spectrometer; and high energy collision-induced dissociation in a high-performance four-sector mass spectrometer with massive cluster-impact ionization.

Amino Acid Sequence↗
PubMed1995

Sequencing peptides without scanning the reflectron: post-source decay with a curved-field reflectron time-of-flight mass spectrometer.

A time-of-flight mass spectrometer has been developed using a reflectron in which the voltages placed on the lens elements correspond to a function describing the arc of a circle. This curved-field reflectron enables acquisition of focused product-ion mass spectra at a single reflectron voltage. In this paper, we present results from this instrument for the amino acid sequencing of several peptides and describe the method of mass calibration.

Amino Acid Sequence↗
PubMed1994

Characterization of the neutral products formed upon the charge-remote fragmentation of fatty acid ions.

Collisionally activated dissociation (CAD) of the carboxylate anions, [M-H]-, or dilithiated cations, [M-H+2Li]+, from fatty acids results in charge-remote fragmentations at the alkyl chain C-C bonds leading to structure-indicative fragment ions. The neutral molecules eliminated during these reactions are characterized in this study using neutralization-reionization mass spectrometry (NRMS). The major neutral losses detected are alkenes (or dienes, in the case of monounsaturated fatty acids), not alkanes or alkyl radicals. This is consistent with the initially proposed mechanism proceeding by a pericyclic 1,4-elimination of H2.

Fatty Acids↗
PubMed1993

The neutral products formed during backbone fragmentations of protonated peptides in tandem mass spectrometry.

Collisionally activated dissociation (CAD) of the protonated polyalanines Ala-Ala,Ala-Ala-Ala, and Ala-Ala-Ala-Ala causes breakup of the peptide bonds leading to sequence-indicative fragment ions. The neutral molecules eliminated during these reactions are identified here using neutralization-reionization mass spectrometry (NRMS). N-terminal acylium ions (bn) arise after the C-terminus is lost as an intact amino acid or peptide; further loss of CO leads to immonium ions (an). Upon generation of C-terminal sequence ions (yn), a hydrogen atom attached to a nitrogen rearranges from the N-terminal to the C-terminal side yielding a protonated amino acid (y1) or peptide (y > or = 2) as the ionic fragment; the complementary neutral fragment is an aziridinone if the N-terminal amino acid is cleaved and a diketopiperazine if two N-terminal amino acid units are eliminated. Detection of neutral dissociation products can reveal valuable structure information, as demonstrated with the tetrapeptides Val-Gly-Ser-Glu and Val-Gly-Asp-Glu.

Amino Acid Sequence↗