Nucleic acids separation mechanism

Cystalline hydroxylapatite [Cai0 (P04)6 (OH)2] is an adsorbent used to separate mixtures of proteins or nucleic acids. The mechanism of adsorption is not fully understood but is thought to involve both the calcium ions and phosphate ions on the surface and to involve dipole-dipole interactions and possibly electrostatic attractions. One of the most important applications of hydroxylapatite chromatography is the separation of single-stranded from double-stranded DNA. Both forms of DNA bind at low phosphate buffer concentrations but as the buffer concentration is increased further, double-stranded DNA is released. The affinity... 

This review gives an overview of current advances in nucleic acid separation by CE and microchip electrophoresis. The focus is on the separation mechanisms during CE, conventional separation matrices and thermoresponsive polymers solutions, UV and fluorescence detection, microchip-based CE, and entropic trapping networks. 

Once chirality is induced and amplified by some mechanism, the excess must first persist and then propagate in order to survive. A distinctive characteristic of homo-chiral protein and nucleic acid biopolymers is that they function within the enclosed environment of cells, which provide a membranous boundary structure that separates the intracellular components from the external environment. It has accordingly been postulated frequently that analogous but simpler enclosed environments must have been available and operative on the primitive Earth. 

Previous theoretical treatments of the transition between the helicel and random forms of the desoxyribose nucleic acid (DNA) molecule are extended to Include formally the explicit consideration of the dissociation into two separate chains and the consideration of the effects of the.ends of the chains, An approximate form for the fraction of the base pairs that are bonded is obtained in terms of two parameters, a stability constant for base pairing and a constant representing the interaction of adjacent base pairs. The matrix method of statistical mechanics proves to be adaptable to this problem. Some numerical examples are worked out for very long molecules, for which case it is found that the effect of concentration is small. 

RNA replicase isolated from Qj8-infected E. coli cells catalyzes the formation of an RNA complementary to the viral RNA, in a reaction equivalent to that catalyzed by DNA-dependent RNA polymerases. New RNA strand synthesis proceeds in the 5 —>3 direction by a chemical mechanism identical to that used in all other nucleic acid synthetic reactions that require a template. RNA replicase requires RNA as its template and will not function with DNA. It lacks a separate proofreading endonuclease activity and has an error rate similar to that of RNA polymerase. Unlike the DNA and RNA polymerases, RNA replicases are specific for the RNA of their own virus the RNAs of the host cell are generally not replicated. This explains how RNA viruses are preferentially replicated in the host cell, which contains many other types of RNA. 

Hydrophobic interaction chromatography (HIC) is a mode of separation in which molecules in a high-salt environment interact hydrophobically with a nonpolar bonded phase. HIC has been predominantly used to analyze proteins, nucleic acids, and other biological macromolecules by a hydrophobic mechanism when maintenanee of the three-dimensional structure is a primary eoneern [1-4]. The main applications of HIC have been in the area of protein purification because the reeovery is frequently quantitative in terms of both mass and biological activity. 

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