A highly regulated, recording constant power, voltage, and current supply for electrophoresis and isoelectric focusing.

Assays for endonuclease and ligase activities have been devised that make use of the fact that circular phage λ DNA is preferentially retained on nitrocellulose filters while linear λ DNA is not. The assay is rapid, time dependent, and quantitative and has been used for the purification of restriction endonucleases and DNA ligases.     

Capillary electrophoresis of caseino-peptides: influence of applied voltage and column temperature

The peptides formed upon action of purified cardoon rennet on the Ala₁₈₉-Phe₁₉₀-Leu₁₉₁-Leu₁₉₂-Tyr₁93 -casein fragment were separated by capillary electrophoresis in an uncoated fused silica capillary. There was a linear correlation between electrophoretic mobility and Z/M^2/3 (Z, net charge; M, molecular mass) under all experimental conditions tested; under the optimal condicitions, 25 kV and 40 °C, the correlation coefficient was 0.994. The reported method is fast (migration times less than 7 min) and may be used to study the action of aspartic proteinases on the C-terminal domain of -casein and thus to help elucidate their effect on cheese quality.     

An economic "power supply" using a diode for agarose and polyacrylamide gel electrophoresis

Gel electrophoresis using agarose and polyacrylamide is a technique widely used for the separation of DNA and protein of various molecular sizes. This type of electrophoresis involves use of a rather expensive dc power supply composed of a complicated circuit. A simple circuit consisting of a single diode was designed, which can be used as a substitute for the conventional power supply. There are no appreciable differences in the so-obtained electrophoretic patterns. This simple, economic system is expected to be applied for use in laboratory, industrial, educational, and clinical facilities.     

Accelerated liquid isolectric focusing using a direct current source that maintain constant power.

A power supply has been designed to improve liquid isoelectric focusing by automatically maintaining constant power applied to the column. The main advantages are (a) a reduced exposure time which is particularly important when sensitive proteins are being resolved; (b) a reduction in the loss of resolution due to diffusion or denaturation of the proteins; and (c) a considerable increase in efficiency of the use of the equipment for preparative purposes.     

Constant normal pressure, constant surface tension, and constant temperature molecular dynamics simulation of hydrated 1,2-dilignoceroylphosphatidylcholine monolayer

A constant normal pressure, constant surface tension, and constant temperature (NP(N)gammaT) molecular dynamics (MD) simulation of the liquid condensed phase of a 1,2-dilignoceroylphosphatidylcholine (DLGPC) monolayer has been performed at 293.15 K. A DLGPC molecule has two saturated 24-carbon acyl chains, giving the hydrocarbon core thickness of the monolayer approximately 28 A, which is close to the hydrocarbon core thickness of a membrane of a living system. NP(N)gammaT ensemble was used to reproduce the experimental observations, such as area/lipid, because surface tension is an essential factor in determining the monolayer structure. Data analysis on DLGPC/water monolayer shows that various liquid condensed-phase properties of the monolayer have been well reproduced from the simulation, indicating that surface tension 22.9 mN/M used in the simulation is an appropriate condition for the condensed-phase NP(N)gammaT simulation. The simulation results suggest that this long-chain phospholipid monolayer shares many structural characteristics with typical short-chain 1,2-diacylphosphatidylcholine systems, such as DPPC/water monolayer in the condensed phase and DPPC/water bilayer in the gel phase. Furthermore, it was found that DLGPC/water monolayer has almost completely rotationally disordered acyl chains, which have not been observed so far in short-chain 1,2-diacylphosphatidylcholine/water bilayers. This study indicates the good biological relevance of the DLGPC/water monolayer which might be useful in protein/lipid studies to reveal protein structure and protein/lipid interactions in a membrane environment.     

Molecular dynamics simulations of a fluid bilayer of dipalmitoylphosphatidylcholine at full hydration, constant pressure, and constant temperature.

Molecular dynamics simulations of 500 ps were performed on a system consisting of a bilayer of 64 molecules of the lipid dipalmitoylphosphatidylcholine and 23 water molecules per lipid at an isotropic pressure of 1 atm and 50 degrees C. Special attention was devoted to reproduce the correct density of the lipid, because this quantity is known experimentally with a precision better than 1%. For this purpose, the Lennard-Jones parameters of the hydrocarbon chains were adjusted by simulating a system consisting of 128 pentadecane molecules and varying the Lennard-Jones parameters until the experimental density and heat of vaporization were obtained. With these parameters the lipid density resulted in perfect agreement with the experimental density. The orientational order parameter of the hydrocarbon chains agreed perfectly well with the experimental values, which, because of its correlation with the area per lipid, makes it possible to give a proper estimate of the area per lipid of 0.61 +/- 0.01 nm2.     

Capillary electrophoresis and microdialysis: current technology and applications

Microdialysis sampling has become an important method for the continuous monitoring from an in vivo environment. This technique has been used to monitor many endogenous molecules, such as neurotransmitters, as well as exogenous species such as drug substances. Microdialysis samples have traditionally been analyzed by liquid chromatographic (LC) methods to gain resolution and quantification of the molecules of interest. However, LC separations have a relatively large injection volume requirement which, as a consequence, increases microdialysis sampling times. Capillary electrophoresis (CE), with its very small sample volume requirements and high resolving power, has therefore gained popularity as an alternative to LC. Reviewed here are many of the technologies currently available for CE and examples of how this technique has been effectively applied to the analysis of microdialysis samples.     

A new convenient column for gel electrophoresis,isoelectric focusing,and zonal electrophoresis

A simple preparative electrophoresis column that can be utilized for gel and zonal electrophoresis and isoelectric focusing has been constructed.     

Gut clearance rate constant, temperature and initial gut contents: a review

The influence of temperature (T) and initial gut contents onestimates of copepod gut clearance rate constant (GCRC) is reviewedfrom literature data. Previous results on the relationship betweentemperature and GCRC are confirmed, and the inclusion of initialgut contents did not increase the significance of the model.Nevertheless, a significant difference was found between theexperiments performed with pre-fed animals and animals fromthe environment. A high percentage of variability remains unexplained,but part of this is likely to be due to experimental error anddiffer ences in the methods used.