Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have successfully amplified D17S74 (CMM86) alleles by a long-distance polymerase chain reaction (PCR) using TaKaRa Ex Taq (a Taq DNA polymerase with a 3'-exonuclease activity) and Perfect Match Polymerase Enhancer (a special polymerase enhancer). We adopted a hot-start technique with TaqStart antibody. Because of the high guanine content (60%) in D17S74 alleles, removal of K+ from the buffers was quite effective. The use of K(+)-free buffers reduces premature chain termination in G-rich regions, thereby facilitating amplification of targets containing such sequences. The 17 alleles amplified from DNA samples of 72 unrelated Japanese subjects ranged from 1.05 to 3.5 kb, with a heterozygosity of 92%. PCR amplification of D17S74 alleles makes their detection simpler than by conventional Southern blotting, and increases the practical utility of the locus.
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PMID:Long-distance PCR of VNTR at the D17S74 (CMM86) locus. 875 89

A modified allele-specific competitive blocker PCR (ACB-PCR) has been developed as an approach for genotypic selection, the detection of a rare mutant allele based solely upon its altered nucleotide sequence. ACB-PCR genotypic selection operates through the preferential PCR amplification of mutant DNA using a primer that has more mismatches to the wild-type allele than the mutant allele. In addition, a blocker-primer with a 3'-terminal dideoxynucleotide and more mismatches to the mutant allele than the wild-type allele is incorporated to reduce the background and increase sensitivity. Using ACB-PCR, the CAA-->AAA base substitution at codon 61 of the mouse H-ras gene was detected regularly at mutant fractions of 10(-5). To accurately quantify the occurrence of this particular mutation, an internal amplification standard (AS) DNA was constructed. The H-ras and AS DNAs were subject to the same genotypic selection but were amplified using different upstream primers to give PCR products that can be distinguished by size. Defined mixtures of mutant and wild-type AS DNAs were used to study the effects of various components of the ACB-PCR. The concentration of dNTPs, blocker primer and Perfect Match Polymerase Enhancer, as well as the choice of thermostable DNA polymerase and annealing temperature were examined. Conditions were identified for the concurrent detection of the CAA-->AAA mutation in the H-ras and AS DNAs. Using the identified conditions, approximately equal signals were obtained from equivalent amounts of the two DNA templates over a wide range of mutant fractions (1 in 10 to 1 in 10(5)). This ACB-PCR method can be used for any application where it is necessary to quantify relatively small mutant fractions.
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PMID:Detection of a mouse H-ras codon 61 mutation using a modified allele-specific competitive blocker PCR genotypic selection method. 986 88