Thiamine-Binding Protein of Escherichia coli

The ability to transport thiamine in Escherichia coli was reduced by osmotic shock treatment with a concomitant release of a thiamine-binding protein; its formation was repressed by thiamine added to the growth medium.     

Fluorescence energy transfer in tryptophanase

Excitation of apotryptophanase from Escherichia coli$\text{B}\text{lt7-A}$ at 290 nm yielded a fluorescence emission centered at 340 nm. Binding of pyridoxal phosphate to apoenzyme induced quenching of protein fluorescence concomitant with an appearance of another peak at 510 nm by way of energy transfer from tryptophan. Based on the results, an approximate distance between the coenzyme and tryptophan was estimated to be 18–24 Å according to the Förster's theory. The ozone-inactivated enzyme yielded only the 340 nm-peak upon excitation at 290 nm following reconstitution with the coenzyme. The fluorescence decay time of the tryptophyl residue was somewhat increased by ozone-inactivation. These results suggest that the tryptophyl residue essential for the activity is involved in a direct interaction with the coenzyme.     

Two flavonol glycosides, hexandrasides C and D, from the underground parts of Vancouveria hexandra.

In addition to four known glycosides, icariin, epimedin B, epimedosides A and E, two new glycosides of a flavonol with a gamma,gamma-dimethylallyl group were isolated from the underground parts of Vancouveria hexandra. The structures were determined to be des-O-methyl-anhydroicaritin 3-O-beta-D-xylopyranosyl(1----2)-alpha-L-rhamnopyranoside 7-O-beta-D-glucopyranosyl(1----2)-beta-D-glucopyranoside and anhydroicaritin 3-O-alpha-L-rhamnopyranosyl(1----3)-alpha-L-rhamnopyranoside 7-O-beta-D-glucopyranoside by means of spectral analysis.     

Restitution of hemagglutinating activity to spikeless particles of HVJ (Sendai virus) by glycoprotein components of Newcastle disease virus.

Spikeless particles of HVJ (Sendai virus) lacking in hemagglutinating (HA) activity were obtained by enzymatic digestion of virions with trypsin followed by centrifugation through a sucrose gradient. When they were mixed with glycoprotein components of Newcastle disease virus (NDV) obtained by treatment of purified virions with deoxycholate (DOC), the mixture showed hemagglutination reaction, which was inhibited by anti-NDV serum, but not by anti-HVJ serum. Sedimentation profile of the HA active agents was then examined by centrifugation of the mixture of spikeless particles of HVJ (labeled with 3H-uridine) and glycoproteins of NDV (labeled with 14C-amino acid mixture). The results showed that the peak of HA activity had both of the radioactivities, and that the sedimentation rate of the HA was faster than that of spikeless HVJ but slower than that of intact HVJ. Electron micrographs of such HA active structures showed that they were morphologically closely similar to intact virion of HVJ, although they had neither hemolytic activity nor infectivity. The mixture of spikeless HVJ and glycoproteins of HVJ or NDV which were removed from virions by proteolytic enzymes, on the other hand, did not show any detectable hemagglutinating activity.     

Inhibition of Thiamine Transport by Chloroethylthiamine in Escherichia coli

Chloroethylthiamine was found to inhibit an entrapment of thiamine as thiamine monophosphate by blocking thiamine monophosphokinase in the cytoplasm after thiamine was taken up by the cells of Escherichia coli.     

Mutation associated with an autosomal dominant cone-rod dystrophy CORD7 modifies RIM1-mediated modulation of voltage-dependent Ca2+ channels

Genetic analyses have revealed an association between the gene encoding the Rab3A-interacting molecule (RIM1) and the autosomal dominant cone-rod dystrophy CORD7. However, the pathogenesis of CORD7 remains unclear. We recently revealed that RIM1 regulates voltage-dependent Ca(2+) channel (VDCC) currents and anchors neurotransmitter-containing vesicles to VDCCs, thereby controlling neurotransmitter release. We demonstrate here that the mouse RIM1 arginine-to-histidine substitution (R655H), which corresponds to the human CORD7 mutation, modifies RIM1 function in regulating VDCC currents elicited by the P/Q-type Ca(v)2.1 and L-type Ca(v)1.4 channels. Thus, our data can raise an interesting possibility that CORD7 phenotypes including retinal deficits and enhanced cognition are at least partly due to altered regulation of presynaptic VDCC currents.     

Isolation and purification of the major photosynthetic antenna, fucoxanthin-Chl a/c protein, from cultured discoid germilings of the brown Alga, Cladosiphon okamuranus TOKIDA (Okinawa Mozuku)

A chlorophyll c binding membrane intrinsic light-harvesting complex, the fucoxanthin-chlorophyll a/c protein (FCP), was isolated from cultured discoid germilings of an edible Japanese brown alga, Cladosiphon (C.) okamuranus TOKIDA (Okinawa Mozuku in Japanese). The discoid germiling is an ideal source of brown algal photosynthetic pigment-protein complexes in terms of its size and easiness of cultivation on a large scale. Ion-exchange chromatography was crucial for the purification of FCP from solubilized thylakoid proteins. The molecular weight of the purified FCP assembly was estimated to be ~56?kDa using blue native-PAGE. Further subunit analyses using 2D-PAGE revealed that the FCP assembled as a trimer consisting of two distinguishable subunits having molecular weights of 18.2 (H) and 17.5 (L)?kDa. Fluorescence and fluorescence-excitation spectra confirmed that the purified FCP assembly was functionally intact.