Characterization and serologic analysis of the Treponema pallidum proteome.

Treponema pallidum subsp. pallidum is the causative agent of syphilis, a sexually transmitted disease characterized by widespread tissue dissemination and chronic infection. In this study, we analyzed the proteome of T.

Evidence for the proteolytic processing of dentin matrix protein 1. Identification and characterization of processed fragments and cleavage sites.

Full-length cDNA coding for dentin matrix protein 1 (DMP1) has been cloned and sequenced, but the corresponding complete protein has not been isolated. In searching for naturally occurring DMP1, we recently discovered that the extracellular matrix of bone contains fragments originating from DMP1. Shortened forms of DMP1, termed 37K and 57K fragments, were treated with alkaline phosphatase and then digested with trypsin.

Identification of a phosphorylation site in the hinge region of the human progesterone receptor and additional amino-terminal phosphorylation sites.

We have previously reported the identification of seven in vivo phosphorylation sites in the amino-terminal region of the human progesterone receptor (PR). From our previous in vivo studies, it was evident that several phosphopeptides remained unidentified. In particular, we wished to determine whether human PR contains a phosphorylation site in the hinge region, as do other steroid receptors including chicken PR, human androgen receptor, and mouse estrogen receptor.

Identification and characterization of the carboxyl-terminal region of rat dentin sialoprotein.

Two acidic proteins, dentin sialoprotein (DSP) and dentin phosphoprotein (DPP), are present in the extracellular matrix of dentin but not in bone. These two proteins are expressed in odontoblasts and preameloblasts as a single cDNA transcript coding a large precursor protein termed dentin sialophosphoprotein (DSPP). DSPP is specifically cleaved into two unique proteins, DSP and DPP.

A 21-kDa C-terminal fragment of protein-disulfide isomerase has isomerase, chaperone, and anti-chaperone activities.

A catalyst of disulfide formation and isomerization during protein folding, protein-disulfide isomerase (PDI) has two catalytic sites housed in two domains homologous to thioredoxin, one near the N terminus and the other near the C terminus. The thioredoxin domains, by themselves, can catalyze disulfide formation, but they are unable to catalyze disulfide isomerizations (Darby, N. J.

Metabolism of leukotriene C4 in gamma-glutamyl transpeptidase-deficient mice.

We have investigated the metabolism of leukotriene C4 (LTC4) in gamma-glutamyl transpeptidase (GGT)-deficient mice (Lieberman, M. W., Wiseman, A.

Species-dependent post-translational modification and position 2 allelism: effects on streptococcal superantigen SSA structure and V beta specificity.

Epidemiologic and molecular population genetic analyses support a role for superantigens (SAg) in the pathogenesis of severe staphylococcal and streptococcal infections. To investigate how variations in SAg structure influence immunomodulatory activity, we examined the biochemical and functional properties of two allelic variants of streptococcal SAg SSA that differ at position 2. Mass spectrometry revealed both recombinant (Escherichia coli) and native (Streptococcus pyogenes) SSA allelic variants to have significantly larger molecular masses than predicted by primary sequence alone and provided evidence that the proteins were modified by the addition of biochemical moieties, a phenomenon that has not been described for related SAg.

Methyl-donor deficiency due to chemically induced glutathione depletion.

Dietary deficiency of methionine (Met) is known to deplete cellular Met and cause DNA hypomethylation, but depletion of Met and impairment in methylation due to chemically induced glutathione (GSH) depletion has escaped recognition. In this study, the effect of GSH depletion on the Met pool and methylation capability was examined after bromobenzene (BB), a model GSH-depleting hepatotoxin, was administered to the Syrian hamster. An i.

Determination of high-energy fragmentation of protonated peptides using a beqq hybrid mass spectrometer.

A hybrid tandem instrument of BEqQ geometry was used to determine high-energy decomposition of protonated peptides, such as side-chain fragmentation yielding d n and w n ions. The transmission through both E and Q of such product ions, formed in the second field-free region, permits improved mass resolution and confident mass assignment. The experimental technique may involve synchronous scanning of E and Q, or, for the purpose of identification of specific products, limited-range scanning of either E or Q with the other analyzer fixed.

Charge promotion of low-energy fragmentations of peptide ions.

We have examined the hypothesis that structural features which predispose to localization of charge at a strongly favored site are not conducive to the low-energy fragmentation of peptide ions via a multiplicity of pathways. Consistent with this proposal, it is demonstrated that the formation of N- or C-terminal pre-charged derivatives is detrimental to the formation of sequence-specific product ions following low-energy collisional activation. Protonation of pre-charged derivatives (yielding doubly charged ions) restores favorable fragmentation properties; the effect is attributed to the fragmentation-directing properties of the proton which may occupy one of several sites.

Oligosaccharide sequence determination using B/E linked field scanning or tandem mass spectrometry of phosphatidylethanolamine derivatives.

Product ion mass spectral data of [M + H]+ ions of oligosaccharides, mainly tetra- and pentasaccharides, as their dipalmitoyl phosphatidylethanolamine derivatives were obtained using both liquid secondary ion mass spectrometry with B/E linked scanning and fast atom bombardment ionization with collision-induced dissociation/tandem mass spectrometry. Both methods give similar positive product ion spectra of equivalent high sensitivity (detection limits of approximately 50 pmol) that principally contain glycosidic cleavage ions retaining the reducing end of the molecule from which monosaccharide sequence can be deduced. A series of ions from fission of the phosphate ester bond together with glycosidic cleavage are present in the tandem mass spectra and B/E linked scan spectra when helium collision gas is used.

Preparation and tandem mass spectrometric analyses of deuterium-labeled cysteine-containing leukotrienes.

Leukotrienes (LT) C4, E4 and N-acetyl-E4, their respective monomethyl esters and 14,15-2H2 analogs have been synthesized. The collisionally activated decompositions of the [M + H]+ and [M - H]- ions formed by fast atom bombardment (FAB) have been studied by tandem mass spectrometry using a hybrid sector/quadrupole instrument. Structurally informative product ion spectra were obtained for each analyte; the fragmentation pathways proposed are consistent with the parallel data obtained for labeled and derivatized species.