Binding of glycyrrhizin to human serum and human serum albumin

The binding of glycyrrhizin (GLZ) to human serum and human serum albumin (HSA) was examined by an ultrafiltration technique. Specific and nonspecific bindings were observed in both human serum and HSA. The association constants (K) for the specific bindings were very similar: 1.31 x 10(5) M-1 in human serum and 3.87 x 10(5) M-1 in HSA. The number of binding sites (n) and the linear binding coefficient (phi) in HSA were 1.95 and 3.09 x 10(3) M-1, respectively. When the human serum protein concentration was assumed to be 4.2% (equal to the measured serum albumin concentration), n in human serum was 3.09, which is similar to the n value in HSA, and phi in human serum was 0.71 x 10(3) M-1, which is reasonably close to that for HSA. The binding pattern of GLZ with human serum protein on Sephadex G-200 column chromatography showed that GLZ binds to only the albumin fraction. It was concluded that the GLZ-binding sites in human serum exist mainly on albumin and GLZ binds to specific and nonspecific binding sites at lower and higher concentrations than approximately 2 mM, respectively.     

Direct lithiation and alkylation of trifluoromethyl enol ethers having a beta-sulfur substituent

The direct lithiation and alkylation of beta-sulfur-alpha-trifluoromethyl substituted enol ethers 1-3 proceeded to give the alkylated products 4a-f, 5, 6a-c in moderate to high yields.     

Rhodium-catalyzed [2 + 2 + 2] cyclotrimerization in an aqueous-organic biphasic system

Macrocyclization via rhodium-catalyzed intramolecular [2 + 2 + 2] annulation of triynes has been explored in an aqueous-organic biphasic system. The biphasic system controls the concentration of hydrophobic substrates in the aqueous reaction phase and offers diluted reaction conditions without the use of a slow addition technique. The system also achieves selective cross-annulation between hydrophobic diynes and hydrophilic alkynes.     

Concentration factors of plutonium and americium for marine products

For a realistic dose estimation, we derived the concentration factors (CF) of plutonium and americium for the field measurements of marine products and ambient coastal sea water.The distribution of the concentration ratios (CR) between the concentration in marine products and that in ambient sea water shows a lognormal distribution. The concentration factors of plutonium and americium which are derived as the geometric mean of CR values, are 231 and 67 for whitebait, 12 and 37 for flatfish, 350 and 220 for brown algea, 140 and 670 for shell fish, 27 and 130 for cephalopods, and 250 and 550 for crustaceans, respectively.     

Isolation and characterization of a novel membrane glycoprotein of 85,000 molecular weight from rat liver lysosomes.

We have purified and characterized a novel glycoprotein (r-lamp-3) with an apparent molecular weight (Mr) of 85,000 from membranes of triton-filled lysosomes (tritosomes) by the use of immunoaffinity chromatography on a column of monoclonal antibody-Sepharose 4B. r-lamp-3 accounted for approximately 4% of the total proteins in tritosomal membranes. The isoelectric point (pI) of r-lamp-3 was 4.5 and it was shifted to 6.5 after neuraminidase treatment with its molecular weight decreased by about 7000. Pulse-chase experiments in cultured rat hepatocytes using [35S]methionine showed that r-lamp-3 was initially synthesized as a 77,000 polypeptide and processed to a mature protein with an Mr of 85,000. Upon treatment with endo-beta-N-acetylglucosaminidase H (Endo H), the precursor and mature forms were converted to 55,000 and 73,000 polypeptides, respectively. From the Mr reduction of the precursor form, we estimated the presence of 10--12 N-linked oligosaccharides/r-lamp-3 polypeptide. The data on enzymatic deglycosylation suggested that the mature form of r-lamp-3 contained the same numbers of high mannose-type and complex-type N-linked oligosaccharide chains.     

Cycloleonurinin, a cyclic peptide from Leonuri Fructus

From Leonuri Fructus, a cyclic peptide composed of twelve amino acid residues was isolated. The sequence of the residues was established by mass spectroscopy and by the use of a protein sequencer for the partial hydrolysates obtained by alpha-chymotrypsin.