The polymerase chain reaction (PCR) is a powerful core molecular biology technique, which when coupled to chain termination sequencing allows gene and DNA sequence information to be derived rapidly. A number of modifications to the basic PCR format have been developed in an attempt to increase amplification efficiency and the specificity of the reaction. We have applied the use of DNA-binding protein, gene 32 protein from bacteriophage T4 (T4gp32) to increase amplification efficiency with a number of diverse templates. In addition, we have found that using single-stranded DNA-binding protein (SSB) or recA protein in DNA sequencing reactions dramatically increases the resolution of sequencing runs. The use of DNA-binding proteins in amplification and sequencing may prove to be generally applicable in improving the yield and quality of a number of templates from various sources.
Alternatives for sequencing of PCR products essentially fall into one of two categories; generation of single-stranded DNA for sequencing or the direct sequencing of double-stranded product. Of the two alternatives, sequencing of double-stranded PCR products is likely to be of greatest immediate significance in terms of general applicability and rapidity. Double-stranded sequencing allows the use of the PCR product for other purposes either prior to or subsequent to generation of sequence data. The single-stranded sequencing methods generally require some prior decision regarding sequencing of the product. Assisted by automated workstation development, sequencing of single-stranded DNA PCR products generated either during thermal cycling or following affinity-capture strand separation may have significant future utility, particularly in genome mapping and routine clinical diagnosis. Despite template type and protocol differences, in all situations the purity and concentration of PCR-amplified DNA template used remains the most critical factor determining the efficiency and reliability of nucleotide sequencing methods.
The exquisite specificity of monoclonal antibodies (MAb) has long provided the potential for creating new reagents for the in vivo delivery of therapeutic drugs or toxins to defined cellular target sites or improved methods of diagnosis. However, many difficulties associated with their production, affinity, specificity, and use in vivo have largely confined their application to research or in vitro diagnostics. This situation is beginning to change with the recent developments in the applied molecular techniques that allow the engineering of the genes that encode antibodies rather than the manipulation of the intact antibodies themselves. Techniques, such as the polymerase chain reaction, have provided essential methods with which to generate and modify the genetic constituents of antibodies, allow their conjugation to toxins or drugs, provide ways of humanizing murine antibodies, and allow discrete modular antigen binding components to be produced. More recent developments of in vitro expression systems and powerful phage surface display technologies will without doubt play a major role in future antibody engineering and in the successful development of new diagnostic and therapeutic antibody-based reagents.
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