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.

Adaptive thermal block temperature control method and system

Abstract: Aspects of the present teachings describe a method and apparatus for automatically controlling a block temperature to reduce undershooting and overshooting of the temperatures of a sample contained in the block and participating in a polymerase chain reaction (PCR). The adaptive thermal block temperature control begins when a sample temperature enters a sample window region between a preliminary setpoint temperature and a target setpoint temperature for the sample. Based on thermodynamic behavior of the sample and the predetermined phase of PCR, predicting a time period measured subsequent to the preliminary setpoint temperature when the sample will reach the target setpoint suitable for the predetermined phase of PCR. During this time period, varying the block temperature ramp rate with a series of cooling and heating changes to ensure the block temperature reaches the target setpoint temperature at approximately the same time as the sample reaches the same. Synchronizing the block temperature and sample temperature to the target setpoint temperature reduces undershooting and overshooting of the sample temperature and increases the speed and efficiency of the overall PCR process as it relates to the thermal cycling operations.

A comprehensive on-line digestion-liquid chromatography/mass spectrometry/collision-induced dissociation mass spectrometry approach for the characterization of human fibrinogen.

Abstract: An automatic on-line digestion-liquid chromatography/mass spectrometry/collision-induced dissociation mass spectrometry (LC-MS/CID-MS) protocol has been developed for detection of errors in the biosynthesis of human fibrinogen, such as amino acid (AA) mismatch or incorrect post-translational modification (PTM). Using on-line digestion on an immobilized-enzyme column, the reaction time is significantly reduced (less than 20 min) and the entire approach is suitable for automation. The two-loop MS experiments (full-scan acquisition and sugar moieties monitoring by SIM) allow checking both the correct AA mapping via the peptides generated by the digestion of the PTM. Since the protocol was designed for application on a routine basis, as a proof-of-concept detection of a rare case of ‘abnormal’ fibrinogen has been demonstrated. The advantage of the proposed approach is exemplified by the fact that the DNA sequence information for the case investigated had not shown any evidence of the abnormality. Copyright © 2001 John Wiley & Sons, Ltd.

Automated Chemical Synthesis of PNA and PNA-DNA Chimera on a Nucleic Acid Synthesizer

Abstract: Automated chemical synthesis of PNA and PNA-DNA chimera on a DNA synthesizer using the monomethoxytrityl/acyl protecting group strategy is described.

Oligonucleotide Ligation Assay for Detection of Apolipoprotein E Polymorphisms

Abstract: Apolipoprotein (apo) E is a protein component of lipoproteins, 50% of which resides in HDL, 10% in LDL, 20% in IDL, and 20% in VLDL cholesterol fractions (1). Apo E binds to the LDL receptor, also termed the B,E receptor, because the receptor accepts both apo B and apo E. Apo E is also thought to bind to a specific chylomicron remnant receptor by virtue of its structural determinants. The heterogeneity in receptor binding of different varieties of apo E is explained by the affinity of different apo E alleles to various receptors. Apo E polymorphisms may be explained by three major alleles: apo Ee2, apo Ee3, and apo Ee4, which are found in 10%, 76%, and 13%, respectively, of the Caucasian population (2). The polymorphisms are due to substitution of a cysteine for an arginine at residue 112 or 158, or at both residues. The apo Ee2 variant has the lowest affinity for the LDL receptor. There is an LDL concentration gradient in both the healthy population and in those with coronary heart disease. Individuals homozygous for apo Ee2 have the lowest concentrations of LDL, and apo Ee4 homozygotes have the highest LDL concentrations (3). The apo Ee4 allele has also been associated with Alzheimer disease. However, the mechanisms of this association are not yet clear (4). Thus, the interest in apo E polymorphisms is high, both on the basis of epidemiological research and for the purpose of clarifying individual lipid disturbances or dementias. We have successfully applied the oligonucleotide ligation assay (OLA) technique to screen for mutations causing familial hypercholesterolemia (5). We have now adapted this technique for the detection of apo E polymorphisms in large numbers of samples. PCR amplification of genomic DNA from peripheral blood was performed in a Perkin-Elmer 9600 Thermocycler. A 310-bp fragment of …