Biomedical subjects

Dayin Lin

Publications and source records attributed to Dayin Lin.

5 recordsLinked to original sources

PubMed2006

Characterization of self-assembled supramolecular [Ga4L6] host-guest complexes by electrospray ionization mass spectrometry.

Self-assembled supramolecular host-guest complexes have been characterized by electrospray ionization mass spectrometry. The spectra obtained by use of a Q-TOF instrument equipped with a Z-spray ion source show primarily the 3- and 4- charge states of the assemblies. The assemblies have the general formula [guest subset Ga4L6]11- where L represents the chelating bidentate catechol ligand 1,5-bis(2',3'-dihydroxy-benzamido)naphthalene and guests are tetramethyl ammonium (Me4N+), tetraethyl ammonium (Et4N+), tetra-n-propyl ammonium (Pr4N+) and decamethylcobaltocenium (Cp*2Co+) cations. For the first time, the mass spectrum of the empty assembly [Ga4L6]12- is reported. This article also reports that provided the electrospray ion source is capable of preserving noncovalent interactions, it is possible to observe host-guest complexes containing both weak binding guests as well as sterically demanding guests in the mass spectra. The present data suggest that electrospray mass spectrometry is a powerful tool for characterization of supramolecular host-guest complexes.

Crystallization↗

PubMed2004

Regulation of cell migration and survival by focal adhesion targeting of Lasp-1.

Large-scale proteomic and functional analysis of isolated pseudopodia revealed the Lim, actin, and SH3 domain protein (Lasp-1) as a novel protein necessary for cell migration, but not adhesion to, the extracellular matrix (ECM). Lasp-1 is a ubiquitously expressed actin-binding protein with a unique domain configuration containing SH3 and LIM domains, and is overexpressed in 8-12% of human breast cancers. We find that stimulation of nonmotile and quiescent cells with growth factors or ECM proteins facilitates Lasp-1 relocalization from the cell periphery to the leading edge of the pseudopodium, where it associates with nascent focal complexes and areas of actin polymerization. Interestingly, although Lasp-1 dynamics in migratory cells occur independently of c-Abl kinase activity and tyrosine phosphorylation, c-Abl activation by apoptotic agents specifically promotes phosphorylation of Lasp-1 at tyrosine 171, which is associated with the loss of Lasp-1 localization to focal adhesions and induction of cell death. Thus, Lasp-1 is a dynamic focal adhesion protein necessary for cell migration and survival in response to growth factors and ECM proteins.

Actins↗

PubMed2003

Large-scale protein identification using mass spectrometry.

Recent achievements in genomics have created an infrastructure of biological information. The enormous success of genomics promptly induced a subsequent explosion in proteomics technology, the emerging science for systematic study of proteins in complexes, organelles, and cells. Proteomics is developing powerful technologies to identify proteins, to map proteomes in cells, to quantify the differential expression of proteins under different states, and to study aspects of protein-protein interaction. The dynamic nature of protein expression, protein interactions, and protein modifications requires measurement as a function of time and cellular state. These types of studies require many measurements and thus high throughput protein identification is essential. This review will discuss aspects of mass spectrometry with emphasis on methods and applications for large-scale protein identification, a fundamental tool for proteomics.

Chromatography, Liquid↗

PubMed2003

Statistical characterization of ion trap tandem mass spectra from doubly charged tryptic peptides.

Collision-induced dissociation (CID) is a common ion activation technique used to energize mass-selected peptide ions during tandem mass spectrometry. Characteristic fragment ions form from the cleavage of amide bonds within a peptide undergoing CID, allowing the inference of its amino acid sequence. The statistical characterization of these fragment ions is essential for improving peptide identification algorithms and for understanding the complex reactions taking place during CID. An examination of 1465 ion trap spectra from doubly charged tryptic peptides reveals several trends important to understanding this fragmentation process. While less abundant than y ions, b ions are present in sufficient numbers to aid sequencing algorithms. Fragment ions exhibit a characteristic series-specific relationship between their masses and intensities. Each residue influences fragmentation at adjacent amide bonds, with Pro quantifiably enhancing cleavage at its N-terminal amide bond and His increasing the formation of b ions at its C-terminal amide bond. Fragment ions corresponding to a formal loss of ammonia appear preferentially in peptides containing Gln and Asn. These trends are partially responsible for the complexity of peptide tandem mass spectra.

Mass Spectrometry↗

PubMed2002

Multidimensional separations for protein/peptide analysis in the post-genomic era.

Proteomics is the study of all or part of the protein complement of genes in an organism, often involving the analysis of complex protein/peptide samples. Such complex samples are beyond the separation capacity of 1-D separation techniques. This review describes several multidimensional separations for proteins and peptides. First, several variants of 2-D liquid chromatography (2DLC) are reviewed, including coupled size exclusion-reversed phase, ion exchange-reversed phase, and reversed phase-reversed phase chromatography. Second, we describe coupled liquid chromatography and capillary electrophoresis methods. Finally, a multidimensional protein identification technique (MudPIT) is explained in detail. Each of the described techniques has a much higher separation capacity than 1-D methods and can potentially be automated for high-throughput experiments. In particular, MudPIT takes advantage of both the high separation capacity of 2DLC and the powerful peptide characterization ability of tandem mass spectrometry to analyze complex protein samples. Additional applications and developments of multidimensional liquid separations for proteomics are expected in the future.

Chromatography, Affinity↗