In ligase chain reaction theclinical sample is prepaed according to protocol to which liberates the DNA preseint in the sample the prepared clinical sample is added to reaction mixture containing thermostable DNA ligase a vast excess of two double strand oigonucleotide probes specific to the pathogen to be detected and NAD. The two probes are blunt ended represent contiguous segments of the pathogen genome and each of them long 15 to 30 pair long therefore, the target sequence long the target sequence must be specific to the pathogen to be detected therefore the reaction mixture is beatede in thermocycler to ensure strand separation of both the target DNA and the probes the temperature is then lowereed to 55 temperature to allow the probes to pair with the target DNA now joins the adjacent of one strand of probe of the complementary strands of the two probes are also similarly joined the product of ligation of the two probes is called amplicon.
THE second cycle of LCR is initiated through heating the reaction mixture 94 temperature. In this and subsequent cycles of LCR both the target DNA and the amplicon serve as targets for probes and a result for aomplification this leads to an exponential amplification of the amplication. The amplicons are detected by gel electrophoresis of the reaction mixture ethidium bromide staining and viewing under UV light.
LCR is highly efficient it deetects target molecules in sample having 200-300 targets. It is highly specific and rarely produces false positive signals which is in contrast to PCR. The LCR producere allows automated detection by employing flouresence or hapen labelled probes LCR has been used to detect wide variety infectious agents such as chlamydia trachomatis mycobacterium tuberculosis herpes simplex virus hepatitis B virus Hepatitis C virus etc.
THE second cycle of LCR is initiated through heating the reaction mixture 94 temperature. In this and subsequent cycles of LCR both the target DNA and the amplicon serve as targets for probes and a result for aomplification this leads to an exponential amplification of the amplication. The amplicons are detected by gel electrophoresis of the reaction mixture ethidium bromide staining and viewing under UV light.
LCR is highly efficient it deetects target molecules in sample having 200-300 targets. It is highly specific and rarely produces false positive signals which is in contrast to PCR. The LCR producere allows automated detection by employing flouresence or hapen labelled probes LCR has been used to detect wide variety infectious agents such as chlamydia trachomatis mycobacterium tuberculosis herpes simplex virus hepatitis B virus Hepatitis C virus etc.
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ReplyDeleteNote that, originally, biochemical nomenclature distinguished synthetases and synthases. Under the original definition, synthases do not use energy from nucleoside triphosphates (such as ATP, GTP, CTP, TTP, and UTP), whereas synthetases do use nucleoside triphosphates. It is also said that a synthase is a lyase (a lyase is an enzyme that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure) and does not require any energy, whereas a synthetase is a ligase (a ligase is an enzyme that binds two chemicals or compounds) and thus requires energy.
Enzymatics' high-concentration T4 DNA ligase in combination with the 2X Rapid Ligation buffer greatly stimulates the rate and efficiency blunt-end ligation, therefore long incubations (>10 minutes) are NOT recommended and can greatly reduce the transformation efficiency of ligation products. In order to maximize transformation efficiency of the correct insert/vector combination, the following protocol is recommended.