Protein-nucleic acid probes

If an antibody to the protein of interest is available, it is sometimes possible to use vector sequences, eg, the beta-galactosidase promoter sequence, to direct the transcription of the passenger DNA into messenger RNA and the translation of that mRNA into protein which can be recognized by the antibody. Although this method is somewhat less reHable than the use of nucleic acid probes, specialized vectors are available for this purpose. 

Fluorescent labels, by contrast, can provide tremendous sensitivity due to their property of discrete emission of light upon excitation. Proteins, nucleic acids, and other molecules can be labeled with fluorescent probes to provide highly receptive reagents for numerous in vitro assay procedures. For instance, fluorescently tagged antibodies can be used to probe cells and tissues for the presence of particular antigens, and then detected through the use of fluorescence microscopy techniques. Since each probe has its own fluorescence emission character, more... 

Fluorescence is also a powerful tool for investigating the structure and dynamics of matter or living systems at a molecular or supramolecular level. Polymers, solutions of surfactants, solid surfaces, biological membranes, proteins, nucleic acids and living cells are well-known examples of systems in which estimates of local parameters such as polarity, fluidity, order, molecular mobility and electrical potential is possible by means of fluorescent molecules playing the role of probes. The latter can be intrinsic or introduced on purpose. The high sensitivity of fluo-rimetric methods in conjunction with the specificity of the response of probes to their microenvironment contribute towards the success of this approach. Another factor is the ability of probes to provide information on dynamics of fast phenomena and/or the structural parameters of the system under study. 

Receptor autoradiography and immunohistochemistry are used to demonstrate the final location of receptor proteins. In the nervous system, these receptor proteins are synthesized within soma, but are generally transported to dendrites or axons, distant from cell bodies where they are originated. Thus, demonstration of a receptor population by receptor autoradiography or immunohistochemistry is not sufficient to directly discriminate which perikarya synthesize the receptors (Kuhar et al, 1986 Quirion et al., 1993 Chabot et al., 1999). Knowledge of the sequence of the mRNA coding receptor proteins has made the development of nucleic acid probes possible, which can be used in combination with the... 

Availability of nucleic acid probes for the NR and NiR mRNA and of specific antibodies for the proteins, in addition to measurements of activi-... 

Abstract Now an incisive probe of biomolecular structure, Raman optical activity (ROA) measures a small difference in Raman scattering from chiral molecules in right- and left-circularly polarized light. As ROA spectra measure vibrational optical activity, they contain highly informative band structures sensitive to the secondary and tertiary structures of proteins, nucleic acids, viruses and carbohydrates as well as the absolute configurations of small molecules. In this review we present a survey of recent studies on biomolecular structure and dynamics using ROA and also a discussion of future applications of this powerful new technique in biomedical research. 

The assay for transgene expression involves the transduction of tissue culture cells or animals, and testing for the presence of the transgene protein product. Reagents (antibodies, enzymatic substrates, nucleic acid probes) specific for the transgene product should be made in large quantities, so the assay can be repeated several times. 

Fixation in formalin is suitable because the induced protein-protein and protein-nucleic acid cross-links preserve the tissue efficiently while retaining morphology relatively intact. However, the macromolecular network introduced by formalin significantly reduces the access of FISH probes to target DNA. Consequently, the initial steps in a FISH staining must address suitable breakdown of this network. 

Nucleic acid probes are commonly labeled by enzymatic incorporation of radiolabeled nucleotides or enzymatic addition of radiolabeled phosphate groups to the nucleic acid chain. Proteins, in particular immunoglobulins, are labeled commonly by direct... 

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