Antihypertensive effect and purification of an ACE inhibitory peptide from sea cucumber gelatin hydrolysate

Gelatin from the sea cucumber (Acaudina molpadioidea) was hydrolyzed sequentially with bromelain and alcalase. The hydrolysate was fractionated into three ranges of molecular weight (GH-I, <10 kDa; GH-II, <5 kDa; GH-III, <1 kDa) using an ultrafiltration membrane bioreactor system. The GH-III brought about a high angiotensin-I-converting enzyme (ACE) inhibitory activity, with IC₅₀ value of 0.35 mg/ml. An ACE inhibitory peptide was isolated from the GH-III, using the chromatographic methods including ion-exchange chromatography, gel filtration and reversed phase high-performance liquid chromatography. The purified ACE inhibitory peptide with a molecular weight of 840 Da consisted of five main amino acids (Glu, Asp, Pro, Gly and Ala), and its IC₅₀ value was 0.0142 mg/ml. This sea cucumber gelatin hydrolysate (GH-III) was used as drinks administered to renal hypertensive rats (RHR) for 1 month. The systolic blood pressure and diastolic blood pressure of the RHR were significantly reduced, which indicates an antihypertensive effect by oral administration.     

Fingerprinting of gelatinase subtypes for different topographic regions on non-retaining placenta of Holstein cows

The contribution of matrix metalloproteinases (MMP) to timely discharge of the placenta from bovine uterus at parturition is yet inconclusive, partly because of the presence of multiple MMP forms in situ. In the current study, the expression of different gelatinase subtypes on non-retaining placentas of Holstein cows was fingerprinted by using gelatin zymography. Different topographic regions on the placenta were measured separately, including the placentome-like structure and the fetal and maternal sides of interplacentomal placenta, all sampled from the central and peripheral areas of the placenta, respectively. The spontaneously ruptured umbilical cords were cross-sectioned as fetus end, middle and placenta end also for separate measurement. Body fluids including blood samples from the parturient cows, their neonatal calves and umbilical cord, as well as fetal fluids and the first colostrum were measured concomitantly. Results showed multiple forms of gelatinases subtypes in the placenta tissues and body fluids, including neutrophil gelatinase-associated lipocalin (NGAL)-MMP-9 complex, both the latent and active forms of MMP-2 and MMP-9; of them, the latent forms were much more abundantly and frequently expressed than the active forms. NGAL-MMP-9 complex was more prevalently present in the body fluids than in the placenta tissues. No distinguishable pattern of the expression of any gelatinase subtype was observed among the placentome-like structure, interplacentomal placenta and umbilical cord, or between fetal and maternal sides. Nonetheless, for interplacentomal placenta, proMMP-9 expression was higher in the central than in the peripheral area. In addition, proMMP-2 expression was higher in the rupture end (fetus end) than the placenta end of the umbilical cord. In conclusion, the current validated gelatin zymography detected a gradient proMMP-9 expression on the non-retaining placenta of cows in reverse to the proximity to the umbilical insertion point, and a gradient proMMP-2 expression on a section of the umbilical cord in reverse to the proximity to the rupture site, suggesting roles played by gelatinases in normal discharge of the placenta at term.     

天然聚合物多孔支架的冻干工艺研究

目的 :通过改变冷冻干燥的工艺条件 ,缩短制备聚合物多孔支架的时间。方法 :把冷冻好的聚合物溶液在溶剂的冰点以上直接真空升华干燥 ,通过对支架的孔结构和外观的考察 ,评价其作为制备多孔支架工艺的可行性。结果 :制备了壳聚糖、胶原、明胶 3种不同材料的支架 ,都具有均匀的通孔结构 ,可应用于组织工程研究。结论 :在比冰点高的温度下对冷冻的样品进行真空干燥 ,可以制得多孔支架 ,并能使制备的时间大大缩短 ,但该工艺方案有时会产生开裂和塌陷 ,影响支架的质量 ,因此还有待进一步完善。     

Plasmodium falciparum: stage-specific lactate production in synchronized cultures

Sequential treatment with gelatin followed by sorbitol-produced Plasmodium falciparum cultures that remained synchronous for ? 144 hr. The schizont stage was associated with more lactate production than the other asexual erythrocytic stages of the parasite (11–21 vs 4–7 neq/hr-10⁶ parasitized red blood cells [PRBC]). Lactate production in asynchronous cultures was relatively constant at 8–11 neq/hr-10⁶ PRBC and was directly proportional to parasitemia (P < 0.001).     

The effect of phase viscosity ratio on the rheology of liquid two phase gelatin-locust bean gum systems

The rheological behaviour of liquid two phase gelatin–locust bean gum (LBG) systems, comprising of (a) liquid LBG enriched continuous phase, and (b) flow-deformable gelatin-enriched dispersed particles seems to be determined, at the same phase composition, by phase viscosity ratio (μ). In the μ range from 0.03 to 0.21, viscosity dropped to values noticeably lower (13–40 times) than those of the corresponding LBG solution. Decrease in the viscosity of the mixtures was not observed at μ=0.5–0.6, corresponding that to the maximum energy scatter inside the droplets, in agreement with Mason’s conception of droplet deformation and disruption of liquid Newtonian emulsions.     

Properties of biopolymers produced by transglutaminase treatment of whey protein isolate and gelatin

Byproduct utilization is an important consideration in the development of sustainable processes. Whey protein isolate (WPI), a byproduct of the cheese industry, and gelatin, a byproduct of the leather industry, were reacted individually and in blends with microbial transglutaminase (mTGase) at pH 7.5 and 45 °C. When a WPI (10% w/w) solution was treated with mTGase (10 U/g) under reducing conditions, the viscosity increased four-fold and the storage modulus (G′) from 0 to 300 Pa over 20 h. Similar treatment of dilute gelatin solutions (0.5–3%) had little effect. Addition of gelatin to 10% WPI caused a synergistic increase in both viscosity and G′, with the formation of gels at concentrations greater than 1.5% added gelatin. These results suggest that new biopolymers, with improved functionality, could be developed by mTGase treatment of protein blends containing small amounts of gelatin with the less expensive whey protein.     

壳聚糖和明胶材料对血管平滑肌细胞的作用

壳聚糖是一种具有发展前景的生物材料。研究了不同脱乙酰度壳聚糖、明胶及壳聚糖与明胶共混材料对血管平滑肌细胞生长的促进作用。在不同材料上培养细胞,采集培养后第1天和第5天的图像．在培养24、72、120h时做MTT实验。此外,还用酶联免疫检测(ELISA)方法测量了材料吸附细胞外基质蛋白的数量,探讨细胞外基质蛋白在血管平滑肌细胞与材料相互作用中所起的作用。结果表明脱乙酰度高的壳聚糖材料能较好地促进血管平滑肌细胞的粘附、铺展和生长,可能是一种具有一定应用前景的血管组织工程研究用材料。     

人组织型基质金属蛋白酶抑制剂-1在Pichia pastoris酵母中重组表达研究

 为研究组织型基质金属蛋白酶抑制剂 (TIMPs)的分子作用机制 ,探讨了在 Pichia pastoris酵母中高效表达分泌型人组织型基质金属蛋白酶抑制剂 - 1 (TIMP- 1 )的技术路线 ,并对产物性质进行初步研究 .通过 PCR从含有 TIMP- 1基因的 p BS质粒获得了该基因的全长序列 ,构建了 p PIC9/T1表达载体 ,电击法转化酵母 ,通过表型筛选和 PCR鉴定证实了目的基因已稳定整合入 Pichiapastoris酵母基因组中 .SDS- PAGE表明表达量高达 40 mg/L培养上清 .用免疫印迹法确定了产物的正确性 ;同时 ,反向明胶酶谱法证明了重组蛋白具有抑制基质金属蛋白酶的活性 .