Biomedical subjects

Carla Pasquarello

Publications and source records attributed to Carla Pasquarello.

5 recordsLinked to original sources

PubMed2005

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for quantitation and molecular stability assessment of insulin entrapped within PLGA nanoparticles.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was evaluated for both qualitative and quantitative analysis of insulin entrapped within poly(D,L-lactic-co-glycolic acid) nanoparticles. Quantitation was performed by adding an internal standard (arg-insulin) to defined and unknown sample solutions, in order to reduce point-to-point and sample-to-sample variability. The ratio of the peak height of insulin to the peak height of arg-insulin was plotted against the insulin concentration. In this way, an excellent linear relationship was found (R2 > 0.99). This method of quantitation was compared with classical UV spectroscopy and reverse-phase high-performance liquid chromatography measurements. All methods provided close final drug loading values for the insulin-loaded nanoparticle batches tested. Additionally, with respect to molecular stability, covalent insulin dimers were found only at trace levels in those nanoparticles. Compared with other methods, MALDI-TOF MS is a valuable tool for the characterization of proteins from nanoparticles, because no extensive extraction and complex sampling procedures are required.

Animals↗

PubMed2004

Tumor protein D52 (TPD52): a novel B-cell/plasma-cell molecule with unique expression pattern and Ca(2+)-dependent association with annexin VI.

We generated a murine monoclonal antibody (B28p) detecting an antigenic determinant shared by the immunoglobulin superfamily receptor translocation-associated 1 (IRTA1) receptor (the immunogen used to raise B28p) and an unrelated 28-kDa protein that was subsequently subjected to extensive characterization. The expression of the 28-kDa protein in normal lymphohematopoietic tissues was restricted to B cells and plasma cells and clearly differed from that expected for IRTA1 (selectively expressed by mucosa-associated lymphoid tissue [MALT] marginal zone B cells). Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE)/mass-spectrometry analysis identified the 28-kDa protein as human tumor protein D52 (TPD52), whose expression had been previously described only in normal and neoplastic epithelia. Specific B28p reactivity with TPD52 was confirmed by immunostaining/immunoblotting of TPD52-transfected cells. TPD52 expression pattern in normal and neoplastic B cells was unique. In fact, unlike other B-cell molecules (paired box 5 [PAX5], CD19, CD79a, CD20, CD22), which are down-regulated during differentiation from B cells to plasma cells, TPD52 expression reached its maximum levels at the plasma cell stage. In the Thiel myeloma cell line, TPD52 bound to annexin VI in a Ca(2+)-dependent manner, suggesting that these molecules may act in concert to regulate secretory processes in plasma cells, similarly to what was observed in pancreatic acinar cells. Finally, the anti-TPD52 monoclonal antibody served as a valuable tool for the diagnosis of B-cell malignancies.

Animals↗

PubMed2004

N-t-butyliodoacetamide and iodoacetanilide: two new cysteine alkylating reagents for relative quantitation of proteins.

The synthesis and application of two new alkylating reagents, N-tert-butyl-2-iodoacetamide (N-t-butyliodoacetamide) and 2-iodo-N-phenylacetamide (iodoacetanilide), are described. N-t-Butyliodoacetamide and iodoacetanilide were synthesised to purity in their d(0)-light and in their respective d(9)- and d(5)-heavy forms. The newly synthesised reagents are covalently bound to peptides containing cysteines via an alkylation reaction. The mass differences of 5 and 9 Da avoid possible problems of overlapping isotope distribution. For each alkylated cysteine a peptide mass increases, respectively, by a multiple of 113 and 133 Da for the d(0)-light form of N-t-butyliodoacetamide and iodoacetanilide. These reagents can therefore replace common alkylating reagents in existing proteomics-based applications. Alkylated peptides increase in mass in the same mass range as amino acids and remain suitable for tandem mass spectrometry (MS/MS) data acquisition and analysis. The compounds are simple to use and derivatisation is based on widely applied alkylating procedures. Preliminary results show that these reagents can be applied for both protein quantitation and identification by peptide mass finger printing and/or MS/MS techniques. Using these chemicals and the suggested workflow enables the quantitative analysis of the whole protein sample and realises access to peptides that may contain potential post-translational modifications. Other approaches that incorporate a matrix-assisted laser desorption/ionisation (MALDI) interface prior to MS can take advantage of these chemicals, such as the molecular scanner.

Acetanilides↗

PubMed2004

The molecular scanner: concept and developments.

Approaches aimed at deciphering the proteome have illustrated the need for relatively complex and highly sensitive methodologies. The major elements of proteome analysis, such as powerful protein separation and enzymatic processing, mass spectrometry and dedicated bioinformatics have been assembled in the development of the molecular scanner. This highly flexible and data-rich approach has combined the power of electrophoretic protein separation, the simultaneous digestion and transfer of proteins through an enzymatic membrane, the immediate use of the MALDI mass spectrometer to scan a collecting membrane, and the development of dedicated bioinformatics tools to perform protein identification and molecular imaging of the proteome. Clinical applications of the molecular scanner have also started to be developed for disease diagnosis in biological material.

Animals↗

PubMed2002

Matrix-assisted laser desorption/ionization-tandem mass spectrometry with high resolution and sensitivity for identification and characterization of proteins.

Although peptide mass fingerprinting is currently the method of choice to identify proteins, the number of proteins available in databases is increasing constantly, and hence, the advantage of having sequence data on a selected peptide, in order to increase the effectiveness of database searching, is more crucial. Until recently, the ability to identify proteins based on the peptide sequence was essentially limited to the use of electrospray ionization tandem mass spectrometry (MS) methods. The recent development of new instruments with matrix-assisted laser desorption/ionization (MALDI) sources and true tandem mass spectrometry (MS/MS) capabilities creates the capacity to obtain high quality tandem mass spectra of peptides. In this work, using the new high resolution tandem time of flight MALDI-(TOF/TOF) mass spectrometer from Applied Biosystems, examples of successful identification and characterization of bovine heart proteins (SWISS-PROT entries: P02192, Q9XSC6, P13620) separated by two-dimensional electrophoresis and blotted onto polyvinylidene difluoride membrane are described. Tryptic protein digests were analyzed by MALDI-TOF to identify peptide masses afterward used for MS/MS. Subsequent high energy MALDI-TOF/TOF collision-induced dissociation spectra were recorded on selected ions. All data, both MS and MS/MS, were recorded on the same instrument. Tandem mass spectra were submitted to database searching using MS-Tag or were manually de novo sequenced. An interesting modification of a tryptophan residue, a "double oxidation", came to light during these analyses.

Animals↗