Applied Biosystems

About: Applied Biosystems is a based out in . It is known for research contribution in the topics: Mass spectrometry & Nucleic acid. The organization has 1521 authors who have published 1579 publications receiving 285423 citations.

Automated system for providing a sequence of chemicals to a reaction process

Abstract: An automated system for providing a preselected sequence of chemicals to a reaction. This apparatus includes a track on which a set of cartridges are placed in a preselected order corresponding to an order in which they are to be used in a reaction process. These cartridges are moved past a point at which these chemicals are extracted for use in the process. The chemicals are preferably in liquid form and are contained in containing having a top seal through which a needle can penetrate to extract chemicals for use in the process. These containers preferably contain the aliquot portion needed for the process, thereby providing a mechanism for providing accurate amounts of each chemical to the process.

Characterization of the N+3 Stutter Product in the Trinucleotide Repeat Locus DYS392

Abstract: Stutter products generated during DNA amplification by the polymerase chain reaction (PCR) may complicate mixture interpretation. The PCR amplification of the DYS392 locus typically results in three distinct detectable PCR products: the true allele product (N), a stutter product three bases smaller (N−3), and a reproducible low-level product, three bases larger (N+3). Sequence analysis of the N+3 product demonstrated that its sequence is one TAT repeat longer than the true allele product. Our experiments demonstrated that the quantity of both N−3 and N+3 stutter increased as the allele number increased. The percent stutter also increased as the magnesium concentration was increased in the reaction, as well as when the amount of input DNA was decreased. As both stutter products behave in a similar and reproducible fashion, the same rules that apply to the interpretation of N−3 stutter products in short tandem repeat analysis, can be applied to N+3 stutters. The characterization of the DYS392 N+3 product is the first detailed published study of a stutter product larger than the true allele.

Association between single-nucleotide polymorphisms in the SEC8L1 gene, which encodes a subunit of the exocyst complex, and rheumatoid arthritis in a Japanese population

Abstract: Objective. To identify rheumatoid arthritis (RA) susceptibility genes in a Japanese population by conducting a large-scale case–control association analysis and linkage disequilibrium (LD) mapping on chromosome 7q31–34, a candidate susceptibility locus identified in a preliminary genome-wide scan in 53 Japanese families, using single-nucleotide polymorphisms (SNPs).

Detection of analytes and nucleic acids

Abstract: Methods of detecting at least one analyte and at least one nucleic acid in a sample are provided. Reagents for carrying out the methods are also provided.

Deamidation of labile asparagine residues in the autoregulatory sequence of human phenylalanine hydroxylase

Abstract: Two dimensional electrophoresis has revealed a microheterogeneity in the recombinant human phenylalanine hydroxylase (hPAH) protomer, that is the result of spontaneous nonenzymatic deamidations of labile asparagine (Asn) residues [Solstad, T. and Flatmark, T. (2000) Eur. J. Biochem.267, 6302–6310]. Using of a computer algorithm, the relative deamidation rates of all Asn residues in hPAH have been predicted, and we here verify that Asn32, followed by a glycine residue, as well as Asn28 and Asn30 in a loop region of the N-terminal autoregulatory sequence (residues 19–33) of wt-hPAH, are among the susceptible residues. First, on MALDI-TOF mass spectrometry of the 24 h expressed enzyme, the E. coli 28-residue peptide, L15–K42 (containing three Asn residues), was recovered with four monoisotopic mass numbers (i.e., m/z of 3106.455, 3107.470, 3108.474 and 3109.476, of decreasing intensity) that differed by 1 Da. Secondly, by reverse-phase chromatography, isoaspartyl (isoAsp) was demonstrated in this 28-residue peptide by its methylation by protein-l-isoaspartic acid O-methyltransferase (PIMT; EC 2.1.1.77). Thirdly, on incubation at pH 7.0 and 37 °C of the phosphorylated form (at Ser16) of this 28-residue peptide, a time-dependent mobility shift from tR≈ 34 min to ≈ 31 min (i.e., to a more hydrophilic position) was observed on reverse-phase chromatography, and the recovery of the tR≈ 34 min species decreased with a biphasic time-course with t0.5-values of 1.9 and 6.2 days. The fastest rate is compatible with the rate determined for the sequence-controlled deamidation of Asn32 (in a pentapeptide without 3D structural interference), i.e., a deamidation half-time of ≈ 1.5 days in 150 mm Tris/HCl, pH 7.0 at 37 °C. Asn32 is located in a cluster of three Asn residues (Asn28, Asn30 and Asn32) of a loop structure stabilized by a hydrogen-bond network. Deamidation of Asn32 introduces a negative charge and a partial β-isomerization (isoAsp), which is predicted to result in a change in the backbone conformation of the loop structure and a repositioning of the autoregulatory sequence and thus affect its regulatory properties. The functional implications of this deamidation was further studied by site-directed mutagenesis, and the mutant form (Asn32Asp) revealed a 1.7-fold increase in the catalytic efficiency, an increased affinity and positive cooperativity of L-Phe binding as well as substrate inhibition.