Preparation of nosiheptide liposomes and its inhibitory effect on hepatitics B virus in vitro / 药学学报

<p><b>AIM</b>To prepare liposomes of nosiheptide and study its ability to inhibit hepatitis B virus HBsAg and HBeAg secreted.</p><p><b>METHODS</b>Liposomes of nosiheptide was prepared by sodium deoxycholate dialysis and sonication. Nosheptide was determined by HPLC and partical size was determined by using laser light scattering instrument. Transmission electron microscopy (TEM) was used to examine the morphology of liposomes. Its actions to inhibit hepatitis B virus HBsAg and HBeAg secreted was studied by a HBV-transfectted cell line (HepG2 2. 2. 15 ).</p><p><b>RESULTS</b>Encapsulation efficiency of liposomes by chloroform:methanol (2:1, v/v) was higher than that by dioxane. With the increase of the ratio of nosiheptide: PC (W/W), the encapsulation efficiency of liposomes decreased with the increase of ratio of sodium deoxycholate: PC, the liposomes partical size decreased. The liposomes kept stable at -20 degrees C after 2 years. The drug concentrations of liposomes that inhibit HBsAg secreted by (46.9 +/- 2. 6) %, (55.4 +/- 1.2) %, (65 +/- 3) % and HBeAg secreted by (15.1 +/- 2.3) %, (36.2 +/- 1.7) %, (36.8 +/- 2.5) % were 1.25, 2.5, 5.0 microg x mL(-1), respectively.</p><p><b>CONCLUSION</b>Liposomes of nosheptide can be prepared by sodium deoxycholate dialysis and sonication, which ability to inhibit hepatitis B virus HBsAg and HBeAg secreted is better than nosheptide.</p>

Compared D-amino acid oxidase expression in different Pichia pastoris host strains / 生物工程学报

To compare the DAAO expression level in different Pichia pastoris host strains, the gene encoding DAAO from Trigonopsis variabilis was cloned into plasmid pPIC3.5k and then transformed into P. pastoris GS115 and KM71 respectively. The positive transformants PDK13 (MutS) and PD27 (Mut+) were obtained by PCR analysis. Their optimal and different expression conditions were investigated. To compare with PD27, PDK13 was determined to poss a slower consumption of methanol, a longer induction time, a lower oxygen request and apparently higher expression of DAAO. The highest expression levels were reached up to 2700, 2500 IU/L in shaking flask and 10140, 8463.5 IU/L in fermentor respectively. The over-expression of DAAO can meet its large demand for production of 7-ACA, alpha-keto acid and L-amino acid. In addition, the phenylpyruvate and L-phenylalanine were obtained by crude DAAO reacting with DL-phenylalanine at 37 degrees C for 3h.