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TBL 4
Simone Sweeney, Yousef Talavari, Mena Tawadrous, Candice Thompson, Devin Thompson
QUESTION #3
QUESTION: List and describe two examples in which proteomics has been used for clinical applications.
ANSWER
Proteomics is the systematic evaluation of changes in the protein constituency of a cell. It is a large scale study of proteins, focusing structure and function. It generates a list of proteins; the ultimate goal is to characterize the information flow through protein pathways. Proteomics may be used as a biomarker and therapeutic target. Effective biomarkers must be measurable in accessible body fluid such as serum, urine, or saliva.
Mass spectrometry is used in proteomics; the mass to charge [m/z] ratio versus signal intensity is measured. Recently, there have been developments for serum-based proteomic pattern diagnostics, which is a new method of diagnosis and disease identification for ovarian cancer detection. The new concept is that the diagnostic endpoint for ovarian cancer detection is not a single analyte but a proteomic pattern that is composed of many individual proteins, each of which independently cannot differentiate diseased from healthy individuals.
Additional Info: “Surface-enhanced laser desorption and ionization (SELDI) technology. This type of proteomic analytical tool is a class of mass spectroscopy instrument that is useful in high-throughput proteomic fingerprinting of serum. Using a robotic sample dispenser, 1 µL of serum is applied to the surface of a protein-binding chip. A subset of the proteins in the sample bind to the surface of the chip. The bound proteins are treated with a matrix-assisted laser desorption ionization matrix and are washed and dried. The chip, which contains multiple patient samples, is inserted into a vacuum chamber where it is irradiated with a laser. The laser desorbs the adherent proteins and causes them to be launched as ions. The time of flight (TOF) of the ion before detection by an electrode is a measure of the mass-to-charge (m/z) value of the ion. The ion spectra can be analyzed by computer-assisted tools that classify a subset of the spectra by characteristic patterns of relative intensity.”
The confirmatory HIV test employs a western blot to detect anti-HIV antibody in a human serum sample. Proteins from known HIV-infected cells are separated and blotted on a membrane. Then, the serum to be tested is applied in the primary antibody incubation step; free antibody is washed away, and a secondary anti-human antibody linked to an enzyme signal is added. The stained bands then indicate the proteins to which the patient's serum contains antibody.
REFERENCES:
J. Nutr. July 1, 2003 vol. 133 no. 2476S-2484S.
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