Kinetics and the mechanism of total in vitro hydrolyses (i.e. up to the exhaustion of substrate) of acetylcholine and acetylthiocholine by acetylcholinesterase and butyrylcholinesterase were studied in vitro in a batch reactor at 25 degrees C, pH 8 and ionic strength of 0.11 M. Every hydrolysis was monitored by 2-3 independent analytical methods. All studied types of enzymatic hydrolyses fulfil...

Laser confocal differential interference contrast microscopy (LCM-DIM) allows for the study of the reactivity of surface minerals with slow dissolution rates (e.g., phyllosilicates). With this technique, it is possible to carry out in situ inspection of the reacting surface in a broad range of pH, ionic strength and temperature providing useful information to help unravel the dissolution mechan...

Synthetic microswimmers are envisioned to be useful in numerous applications, many of which occur in tightly confined spaces. It is therefore important to understand how confinement influences swimmer dynamics. Here we study the motility of bimetallic microswimmers in linear and curved channels. Our experiments show swimmer velocities increase, up to 5 times, with the degree of confinement, and...

DNA in cells exhibits a supercoiled state in which the double helix is additionally twisted to form extended intertwined loops called plectonemes. Although supercoiling is vital to many cellular processes, its dynamics remain elusive. In this work, we directly visualize the dynamics of individual plectonemes. We observe that multiple plectonemes can be present and that their number depends on a...

The preparation of spinach ferredoxin by a modification of the method of Keres&es-Nagy and Margoliash which is particularly convenient for large-scale operation is described. The optical, CD, and EPR spectra of this protein are studied in 5 M urea as a function of ionic strength. At high ionic strength the various spectra are very similar to the native protein; at low ionic strength all three s...

1. Methods for the separation from guinea pig serum in highly purified form of three of the components of complement are described. These substances are the so called mid-piece, end-piece, and 4th component. 2. Mid-piece has been separated as a euglobulin, with an electrophoretic mobility of 2.9 x 10(-5) in phosphate buffer of ionic strength 0.2 at pH 7.7, and with a sedimentation constant of 6...

It is known since the early days of molecular biology that proteins locate their specific targets on DNA up to two orders of magnitude faster than the Smoluchowski 3D diffusion rate. It was the idea due to Delbrück that they are non-specifically adsorbed on DNA, and sliding along DNA provides for the faster 1D search. Surprisingly, the role of DNA conformation was never considered in this conte...