Pork peptone stimulates cholecystokinin secretion from enteroendocrine cells and suppresses appetite in rats

We found that soybean beta-conglycinin peptone (BconP) suppresses food intake through cholecystokinin (CCK) release from enteroendocrine cells in association with binding of the peptone to rat small intestinal brush border membrane (BBM). The aim of the present study was to find new appetite suppressing peptides. Peptones from chicken, pork, beef, beef liver, and egg white were examined for activities to bind with rat BBM, CCK-release from enteroendocrine cell line STC-1, and induce satiety in rats. Chicken and pork peptone (ChickP and PorkP) bound to BBM with highest ability as evaluated with a surface plasmon biosensor. PorkP and ChickP released CCK in higher amounts than BconP from STC-1 cells dose-dependently, with highest stimulation by PorkP. An orogastric preload of PorkP, but not ChickP, suppressed food intake similarly to BconP, dose-dependently. These results suggest that PorkP interacts directly with the small intestinal CCK cells to release CCK, and that it suppresses appetite in rats.     

Structural insights into differences in drug-binding selectivity between two forms of human alpha1-acid glycoprotein genetic variants, the A and F1*S forms

Human α(1)-acid glycoprotein (hAGP) in serum functions as a carrier of basic drugs. In most individuals, hAGP exists as a mixture of two genetic variants, the F1*S and A variants, which bind drugs with different selectivities. We prepared a mutant of the A variant, C149R, and showed that its drug-binding properties were indistinguishable from those of the wild type. In this study, we determined the crystal structures of this mutant hAGP alone and complexed with disopyramide (DSP), amitriptyline (AMT), and the nonspecific drug chlorpromazine (CPZ). The crystal structures revealed that the drug-binding pocket on the A variant is located within an eight-stranded β-barrel, similar to that found in the F1*S variant and other lipocalin family proteins. However, the binding region of the A variant is narrower than that of the F1*S variant. In the crystal structures of complexes with DSP and AMT, the two aromatic rings of each drug interact with Phe-49 and Phe-112 at the bottom of the binding pocket. Although the structure of CPZ is similar to those of DSP and AMT, its fused aromatic ring system, which is extended in length by the addition of a chlorine atom, appears to dictate an alternative mode of binding, which explains its nonselective binding to the F1*S and A variant hAGPs. Modeling experiments based on the co-crystal structures suggest that, in complexes of DSP, AMT, or CPZ with the F1*S variant, Phe-114 sterically hinders interactions with DSP and AMT, but not CPZ.     

(+)-5,17-dehydromatrine N-oxide,a new alkaloid in Euchresta japonica

A new lupin alkaloid, (+)-5,17-dehydromatrine N-oxide, was isolated from the fresh aerial parts of Euchresta japonica. Its structure was confirmed by spectrometric data and by direct comparison with a synthetic sample, prepared from (+)-sophoranol ((+)-5-hydroxymatrine). It was also concluded that (+)-5,17-dehydromatrine N-oxide and (+)-matrine N-oxide possess the same configuration with respect to the asymmetric nitrogen by NMR spectra.     

Structure-activity relationship studies of sphingosine-1-phosphate receptor agonists with N-cinnamyl-β-alanine moiety

Structure-activity relationship of sphingosine-1-phosphate receptor agonist was examined. In terms of reducing the flexibility of molecule, hit compound 1 was modified to improve S1P₁ agonistic activity as well as selectivity over S1P₃ agonistic activity. Novel S1P agonists with cinnamyl scaffold or 1,2,5,6-tetrahydropyridine scaffold were identified.     

Imprinted polymer layer for recognizing double-stranded DNA

A method of preparing a thin polymer layer able to recognize double-stranded DNA (dsDNA) was developed by using 2-vinyl-4,6-diamino-1,3,5-triazine (VDAT) as a functional monomer for creating a DNA-imprinted polymer. The formation of hydrogen bonds between VDAT and A-T base pairs in dsDNA was confirmed by measuring the effects of VDAT on the melting point and the NMR and CD spectra of dsDNA. An imprinted polymer that can recognize dsDNA of the verotoxin gene was prepared by polymerizing VDAT, acrylamide, a crosslinking agent, and the template verotoxin dsDNA on a silanized glass surface. The specificity of this polymer layer for binding verotoxin dsDNA was investigated by using fluorescent-labelled dsDNAs. The fluorescence intensity of the polymer layer after binding verotoxin dsDNA was twice as high as after binding oligo(dG)-oligo(dC), indicating that verotoxin dsDNA was preferentially bound to the polymer imprinted with verotoxin dsDNA. The kinetics of verotoxin dsDNA binding to the imprinted polymer were analyzed by surface plasmon resonance measurements. The dissociation constant (KD) was low, of the order of 10(-9)M.     

Substrate recognition ability differs among various prokaryotic tRNase Zs

There exists a significant difference in pre-tRNA preference among prokaryotic tRNase Zs. This is an enigma, because pre-tRNAs should form the common L-shaped structure and tRNase Zs should form the common structure based on the alphabeta/betaalpha-fold. To address this issue, we examined six different eubacterial and archaeal tRNase Zs including two newly isolated tRNase Zs for cleavage of 18 different pre-tRNA substrates. Two Thermotoga maritima, one Thermus thermophilus, one Bacillus subtilis, one Thermoplasma acidophilum, and one Pyrobaculum aerophilum enzymes were tested. To our surprise, the newly isolated proteins T. maritima and T. thermophilus showed the weak tRNase Z activity, even though their primary amino acid sequences are, on the whole, quite different from those of the typical tRNase Zs. We confirmed that substrate recognition ability is quite different among those tRNase Zs. In addition, we found that the optimal conditions as a whole differ significantly among the enzymes. From these results, we provided several clues to solve the enigma by showing the potential importance of the 74th-76th nucleotide sequence of pre-tRNA, the flexible arm length of tRNase Z, the divalent metal ion species, and the histidine corresponding His222 in T. maritima tRNase Z.     

l-Acylimidazoles with Broad-spectrum Fungicidal Activity

The membrane lipids of six higher plants that differ in salt tolerance were analyzed and compared. The root lipids increased in a ratio of glycolipid/phospholipid with increasing salt- tolerance. A similar increase in the ratio was observed with increasing external salinity when halophytic orach and salt-sensitive cucumber were exposed to varying salinity, although the latter plant was limited to only a little increase. Measurements of ion-transport rates with artificial lipid membranes revealed that the root lipids from a salt-resistant plant formed a more permeable membrane than those from a salt-sensitive species. It was found that the membrane permeability was related to the glycolipid/phospholipid ratio in the membrane lipids, where the glycolipids were stimulative and the phospholipids were repressive for ion-flow. These different effects of the two lipid classes may be attributed to their molecular species and head groups.     

A series of nonsecosteroidal vitamin D receptor agonists for osteoporosis therapy

In an extension of our study on gamma hydroxy carboxylic acid analogs, we explored a series of nonsecosteroidal vitamin D receptor (VDR) agonists in which 1,3-diol of 1,25(OH)₂D₃ had been replaced by aryl acetic acid. These analogs showed very potent activity in vitro compared with 1,25(OH)₂D₃. An X-ray analysis of 8d showed that the inserted phenyl ring well mimicked the folded methylene linker of the gamma hydroxy carboxylic acid moiety but the carboxylic acid of 8d interacted with VDR in a different manner from gamma hydroxy carboxylic acids. Through our in vivo screening in an osteoporosis rat model using immature rats, we identified a potent active vitamin D₃ analog, compound 7e. In mature rats of the same model, compound 7e also showed good PK profiling and excellent ability to prevent bone mineral density loss without severe hypercalcemia. Our nonsecosteroidal VDR agonist 7e (CH5036249) could be a possible new drug candidate for treating osteoporosis in human.