ddNTP Mix (for MALDI-TOF MS， 10mM each)

It can be thawed at room temperature. After thawing, it should be stored in an ice box or on an ice bath. After use, it should be stored at -20℃ immediately. During experiments, please use DNase-free or RNase-free pipette tips and centrifuge tubes. This product is for professional scientific research use only and must not be used for clinical diagnosis or treatment, food or pharmaceuticals, or stored in ordinary residences. For your safety and health, please wear a lab coat and disposable gloves when handling this product. ddNTP Mix (for MALDI-TOF MS，10 mM each)，i. e. ，a ddNTP mixture (10 mM each，for MALDI-MS)，is composed of ddATP，ddCTP，ddGTP and ddTTP with each component at 10 mM，and is nuclease-free. This specially formulated ddNTP blend is designed for MALDI-TOF MS and serves as mass-modified terminators. It is used for mass spectrometric analysis after single-base primer extension，and is similar to the iPLEX Termination Mix from Sequenom (Agena). The ddTTP contained herein is specially modified and has a higher molecular weight than regular ddTTP. When incorporated into DNA，ddATP，ddCTP，ddGTP and ddTTP yield distinguishable molecular weights of approximately 271 Da，247 Da，287 Da and 327 Da respectively，which facilitates medium- and high-throughput single nucleotide polymorphism (SNP) analysis via MassArray mass spectrometry. Following the discovery of several matrices capable of ionizing DNA and RNA，matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a powerful platform for nucleic acid research. It is applicable to the detection of sequence variations including mutations，single nucleotide polymorphisms (SNPs)，insertions/deletions and alternative splicing; quantitative variations such as copy number variations，gene expression and allelic expression; as well as genomic DNA methylation and post-transcriptional modifications of tRNA and rRNA. ddNTP stands for Dideoxynucleoside Triphosphate. Compared with dNTP (Deoxynucleoside Triphosphate)，ddNTP possesses a dideoxyribose moiety and lacks the 3’-OH group. It cannot form phosphodiester bonds to ligate subsequent nucleotides，thus terminating strand elongation during DNA synthesis and amplification. Accordingly，ddNTP is also known as a chain-terminating nucleotide. Conventional ddNTPs yield products with small molecular weight differences of 9 Da to 40 Da following single-base primer extension，which impedes medium- and high-throughput genotyping by mass spectrometry. The ddTTP in this product is specially modified to exhibit an increased molecular weight compared with standard ddTTP. Consequently，the molecular weight differences between products exceed 15 Da. Genotyping can be performed based on the mass differences of terminal target bases，making medium- and high-throughput genotyping via mass spectrometry feasible. This product is exclusively developed for MALDI-MS and MALDI-TOF MS. It is a mass grade reagent with HPLC purity ≥ 99%. Each ddNTP is supplied at 10 mM，with a pH of 7. 4 ± 0. 1. The product is nuclease-free，free of DNase and RNase.