Biomedical subjects

Steffen Nock

Publications and source records attributed to Steffen Nock.

6 recordsLinked to original sources

PubMed2003

Protein expression profiling arrays: tools for the multiplexed high-throughput analysis of proteins.

The completion of the human genome sequence has led to a rapid increase in genetic information. The invention of DNA microarrays, which allow for the parallel measurement of thousands of genes on the level of mRNA, has enabled scientists to take a more global view of biological systems. Protein microarrays have a big potential to increase the throughput of proteomic research. Microarrays of antibodies can simultaneously measure the concentration of a multitude of target proteins in a very short period of time. The ability of protein microarrays to increase the quantity of data points in small biological samples on the protein level will have a major impact on basic biological research as well as on the discovery of new drug targets and diagnostic markers. This review highlights the current status of protein expression profiling arrays, their development, applications and limitations.

Journal Article↗

PubMed2003

Recent developments in protein microarray technology.

The sequencing of the human genome and the advent of DNA chips and sophisticated bioinformatics platforms have enabled molecular biologists to take a more global view of biological systems and to analyze naturally occurring genetic variation. Microarrays of antibodies can measure the concentrations of many proteins quickly and simultaneously. Microarrays of genomically encoded proteins allow scientists to screen entire genomes for proteins that interact with particular factors, catalyze particular reactions, or act as substrates for protein-modifying enzymes or as targets of autoimmune responses. The new protein microarray platforms will prove invaluable to basic biological research, and will dramatically accelerate the pace of discovery of drug targets and diagnostic biomarkers.

Drug Design↗

PubMed2003

Optimizing antibody immobilization strategies for the construction of protein microarrays.

Antibody microarrays have the potential to revolutionize protein expression profiling. The intensity of specific signal produced on a feature of such an array is related to the amount of analyte that is captured from the biological mixture by the immobilized antibody (the "capture agent"). This in turn is a function of the surface density and fractional activity of the capture agents. Here we investigate how these two factors are affected by the orientation of the capture agents on the surface. We compare randomly versus specifically oriented capture agents based on both full-sized antibodies and Fab' fragments. Each comparison was performed using three different antibodies and two types of streptavidin-coated monolayer surfaces. The specific orientation of capture agents consistently increases the analyte-binding capacity of the surfaces, with up to 10-fold improvements over surfaces with randomly oriented capture agents. Surface plasmon resonance revealed a dense monolayer of Fab' fragments that are on average 90% active when specifically oriented. Randomly attached Fab's could not be packed at such a high density and generally also had a lower specific activity. These results emphasize the importance of attaching proteins to surfaces such that their binding sites are oriented toward the solution phase.

Animals↗

PubMed2002

Improved method for pepsinolysis of mouse IgG(1) molecules to F(ab')(2) fragments.

Pepsinolysis of immunoglobulin (IgG) to yield F(ab')(2) fragments has been utilized for over 40 years, but the most common subclass of mouse immunoglobulin, IgG(1), is resistant to pepsin cleavage. We show here that this resistance is due to N-linked glycosylation. Deglycosylation by peptide: N-glycosidase F (PNGase F) improves pepsinolysis to generate F(ab')(2) fragments for mouse and rat monoclonal IgG(1) and, in some cases, IgG(2b). This effect was observed for antibodies derived from tissue cell culture or ascites fluid, as well as for polyclonal IgGs from mouse serum. As a result of this finding, the preparation of F(ab')(2) fragments from nearly all mouse IgG molecules should now be a robust procedure.

Animals↗

PubMed2002

Functional protein microarrays.

Microarrays of immobilized functional proteins have the potential to increase dramatically the throughput of proteomic analysis. Micro-immunoassays, in which biological samples are exposed to arrays of immobilized antibodies, can be used for protein expression profiling. In addition, protein function can be elucidated by performing binding and enzymatic assays on arrays of biologically active proteins.

Animals↗

PubMedDate not supplied

Establishment of intein-mediated protein ligation under denaturing conditions: C-terminal labeling of a single-chain antibody for biochip screening.

Intein-mediated protein ligation is a recently developed method that enables the C-terminal labeling of proteins. This technique requires a correctly folded intein mutant that is fused to the C-terminus of a target protein to create a thioester, which allows the ligation of a peptide with an N-terminal cysteine (1, 2). Here we describe the establishment of this method for the labeling, under denaturing conditions, of target proteins that are expressed insolubly as intein fusion proteins. A GFPuv fusion protein with the Mycobacterium xenopi gyrA intein was expressed in inclusion bodies in Escherichia coli and initially used as a model protein to verify intein cleavage activity under different refolding conditions. The intein showed activity after refolding in nondenaturing and slightly denaturing conditions. A construct of the same intein with an anti-neutravidin single-chain antibody was also expressed in an insoluble form. The intein-mediated ligation was established for this single chain antibody-intein fusion protein under denaturing conditions in 4 M urea to prevent significant precipitation of the fusion protein during the first refolding step. Under optimized conditions, the single-chain antibody was labeled with a fluorescent peptide and used for antigen screening on a biochip after final refolding. This screening procedure allowed the determination of binding characteristics of the scFv for avidin proteins in a miniaturized format.

Antibodies↗