A New Cooperation Mechanism of Kinesin Motors when Extracting Membrane Tube

Membrane tubes are important functional elements for riving cells. Experiments have found that membrane tubes can be extracted from giant lipid vesicles by groups of kinesin. How these motors cooperate in extracting the membrane tube is a very important issue but still unclear so far. In this paper, we propose a cooperation mechanism called two-track-dumbbell model, in which kinesin is regarded as a dumbbell with an end （tail domain） tethered on the fluid-like membrane and the other end （head domain） stepping on the microtubule. Taking account of the elasticity of kinesin molecule and the excluded volume effect of both the head domain and the tail domain of kinesin, which are not considered in previous models, we simulate the growth process of the membrane tube pulled by kinesin motors. Our results indicate that in the case of strong or moderate exclusion of motor tails, the average number of motors pulling the tube can be as high as 9 and thus motors moving along a single microtubule protofilament can generate enough force to extract membrane tubes from vesicles. This result is different from previous studies and may be tested by future experiments.     

Synthesis and Crystal Structure of Ethyl 5-Amino-1-[（5＇-methyl-1＇-t-butyl-4＇-pyrazolyl）carbonyl]-3-methylthio-1H-pyrazole-4-carboxylate

The ritle compound has been synthesized and characterized by IR,^1H NMR and X-ray single-crystal diffraction techniques. The results of biological test show that the title compound has fungicidal and plant growth regulation activities.     

^3A＇ and ^3A＂ Energy Surfaces for the VS^＋ ＋ CO2→VO^＋ ＋ COS Reaction

The title reaction proceeds via a one- and two-step mechanism along the ^3A＂ and ^3A＇ surfaces, respectively. The ^3A＇ excited state surface has a lower barrier than the ^3A＂ ground state surface （11.6 and 16.0 kca1/mol, respectively）, We suggest that, at low energies, the reaction proceeds along the A＇ surface and then makes an intersystem crossing to the A＂ surface and yields the ground state product VO^＋（^3∑^-）, which may explain the small VO^＋ cross-section at low energies observed in the experiment     

Synthesis and Crystal Structure of 1-[（1＇-Phenyl-5＇-methyl-4＇-pyrazolcarbonyl）-3-methylthio-5-amino-1Hy l-1,2,4-triazole

The title compound (C14H14N6OS, Mr=314.37) has been synthesized and characterized by IR, ^1H NMR and X-ray single-crystal diffraction techniques.The crystal structure shows the presence of a dimmer with intermolecular N(4)H(4)…N(3) hydrogen bonds.