Background and overview[1][2]
Pyrophosphate is easily soluble in water and is slowly converted into phosphoric acid in cold water. It will be hydrolyzed into phosphoric acid relatively quickly when heated in an acidic solution. It is a tetrabasic acid. The aqueous solution is more acidic than phosphoric acid. The ionization constants are K1>1.4×10-1 and K2= 3.2×10-2, K3＝2.5×10-7, K4＝5.6×10-10. This is completely consistent with the general rule that the greater the degree of condensation of a condensation acid, the stronger the acidity. It can form two types of salts, namely M14P2O7 and M 12H2P2O7, all are toxic.
Pyrophosphate (P2O4-7) has strong compatibility with Mn2+ , Cu2+, Zn2+, Pb2+, Ag+, etc. form a complex Ions, such as Cu(P2O7)2-, Mn2(P2O7)4-2, etc., are often used in the electroplating industry. Pyrophosphate reacts with silver salts to form a white precipitate, but does not precipitate proteins, unlike metaphosphates, allowing them to be identified.
Structure
Apply[2-3]
Pyrophosphoric acid is commonly used as a catalyst, hiding agent and in the preparation of organic phosphates. Examples of its application are as follows:
1. Preparation of a phosphorus oxide modified microporous molecular sieve shape-selective catalyst,
Use microporous molecular sieve ZSM-5 or MCM-22 as the matrix, and use pyrophosphorous acid, hypophosphoric acid, isohythionic diphosphoric acid, pyrophosphoric acid, triphosphoric acid or peroxydiphosphoric acid as the precursor of phosphorus oxide through impregnation and The programmed temperature roasting method loads phosphorus oxide on the outer surface of the microporous molecular sieve, where the mass ratio of the phosphorus oxide to the microporous molecular sieve is 1:6-1:20. The obtained shape-selective catalyst has good shape-selective catalytic performance for toluene disproportionation and ethylbenzene disproportionation processes, and the catalyst preparation method is simple.
2. Pyrosequencing technology.
Pyrosequencing technology (Pymsequencing) is a new type of DNA sequencing technology developed by Nyren et al. in 1987. Its core is an enzyme cascade reaction in the same reaction system catalyzed by four enzymes. The enzymes are: DNA polymerase (DNA poly-merase), ATP sulfurylase (ATP sulfurylase), luciferase (luciferase) and bisphosphatase (apyrase), and the reaction substrate is 5′-phosphoryl sulfate (adenosine 5) ‘-phosphosulfate (APS), fluorescein (luciferin), and the reaction system also includes single-stranded DNA to be sequenced and sequencing primers.
The specific principle is: after the primer anneals to the template DNA, under the synergistic action of the above four enzymes, the polymerization of each dNTP is coupled to the release of a fluorescent signal, and the nuclei of the template DNA are recorded in real time in the form of fluorescent signals. nucleotide sequence.
1) Application in molecular diagnostics: Pyrosequencing technology can quickly and accurately analyze short DNA sequences. It has high throughput, is easy to operate, and facilitates the construction of standardized operating procedures, so it is very popular among many researchers. Monstein et al. used pyrosequencing technology to detect the variable V1 and V3 region sequences of the 16S rRNA gene (16S rDNA) of Helieobacter pylori, and classified 23 Helicobacter pylori specimens obtained from gastroscopy biopsy specimens based on their V1 region (No. 75 ~100) nucleotide sequence differences, and 6 different allele types were identified. Except for 11 samples that were consistent with the sequence of Helicobacter pylori strain 26695 and one sample that was consistent with the sequence of J99 strain, according to the changes in the V1 region It manifests itself as a mutation of 1 or 2 nucleotides or an insertion of a single nucleotide and is divided into 4 allele types.
C to T conversion occurred in the V3 region (990-1020) of another 2 specimens, proving that this technology can meet the requirements for rapid identification and typing of clinical pathogenic bacteria specimens. In addition, the characteristics of pyrosequencing technology are very suitable for sequencing and analysis of DNA with known short sequences. The Pyrosequencing technology and analysis system developed by Pymsequencing AB have the ability to sequence and analyze a large number of samples (96). Therefore, it can It is said that pyrosequencing technology provides an ideal technical operation platform for large-throughput, low-cost, timely, fast and intuitive SNPs research and clinical testing.
2)���Applications in forensic identification
In the field of forensic identification, traditional mitochondrial DNA analysis uses Saner sequencing to analyze the two highly variable regions HVI and HV II regions of its D-Loop region. Although it is very effective, it consumes a lot of time and labor. Andreasson et al. used pyrosequencing technology to sequence and analyze the polymorphic sites in the DNA-Loop region of the mitochondrial imported polymer flocculant, proving that this technology is faster, more accurate and more sensitive, and its efficiency is greatly improved.
3) Application in pharmacogenomics
Genetic polymorphisms are the basis of pharmacogenomics. The existence of these polymorphisms may lead to individual differences in drug efficacy and toxic and side effects in many drug treatments. The analysis of polymorphic sites through pyrosequencing technology provides a fast and efficient tool for drug response research. Sweden’s Eurona Medical AB collaborated with Pyrosequencing to use this technology to analyze SNPs of angiotensin-converting enzyme (ACE), and 11 known polymorphic sites that function in the renin-angiotensin-aldosterone system (RAAS pathway). Sequencing analysis was performed to distinguish the different homozygous and heterozygous genotypes of exon 15 and exon 8 very accurately, and satisfactory results were obtained.
4) Application in agricultural biology
In the study of plant polymorphism analysis such as SNPs in tetraploid potatoes, pyrosequencing technology was used to type tetraploid potato genes, and 94 polymorphic sites were detected in Kao antistatic agents. , it was found that 76 allele loci could be identified using this technology, with an efficiency of 81%, indicating that this technology is more accurate in quantitation than traditional Sanger sequencing and single-base extension methods. In addition to limitations in sequencing length, this technology is more suitable for SNP analysis of polyploid species because it can not only accurately distinguish homozygotes and heterozygotes, but also distinguish different heterozygous states.
In the study of animal polymorphisms such as pigs, pyrosequencing technology was used to find that the increased glycogen content of pig skeletal muscles is related to an irreversible base substitution of the PRKAG3 gene, which encodes a pig muscle-specific gland. Regulatory subunit of glycoside monophosphate-activated protein kinase (AMPK) isoforms.
To sum up, pyrosequencing technology is a high-throughput, highly automated sequencing technology that is easy to operate and is very suitable for rapid detection of large samples. It saves time, effort and cost, and is incomparable to the Sanger method. The advantages. At present, Pyrosequencing technology has gradually become a very important new method of DNA analysis in laboratories and has been widely used in many aspects. Pyrosequencing is receiving the attention of more and more researchers.
Currently, its technology is widely used in genetic analysis, SNP analysis, molecular diagnosis, bacterial and viral typing, methylation analysis, forensic identification and pharmacogenomics. Of course, pyrosequencing technology can only analyze short sequences of 25 to 30 nucleotides. It is believed that as the level of this technology is further improved, improved and perfected, the application of pyrosequencing technology will become more widespread.
Preparation [1]
Heating disodium hydrogen phosphate to obtain sodium pyrophosphate, dissolve it and then add lead salt to produce a lead pyrophosphate precipitate. Suspend this precipitate in water, pass in hydrogen sulfide gas to obtain lead sulfide precipitate, filter the filtrate Pure pyrophosphoric acid can be produced by concentrating under vacuum and low temperature; pyrophosphoric acid can also be produced by heating orthophosphoric acid at 250°C.
Main reference materials
[1] Encyclopedia of Chinese Middle School Teaching·Chemistry Volume
[2] Ni Hongbing, Ju Shaoqing, Wang Huimin. Progress in pyrosequencing technology and its application [J]. Foreign Medicine: Clinical Biochemistry and Laboratory Science, 2005, 26(9): 600-602.
[3] CN201410516173.9 Preparation method of phosphorus oxide modified microporous molecular sieve shape-selective catalyst
