The terminal protein of the linear DNA plasmid pGKL2 shares an N-terminal domain of the plasmid-encoded DNA polymerase

The 36K protein attached at the 5′ end of the linear DNA plasmid pGKL2 from the yeast Kluyveromyces lactis was first purified and characterized. The terminal protein was purified from cells (1 kg wet weight) by ammonium sulphate precipitation and two rounds of centrifugation to equilibrium in CsCl gradients. The pGKL2 was present only in the post-microsomal supernatant. Approximately 10 mg of the purified pGKL2 was recovered and digested with DNase I. The terminal protein (final ca. 0·8 mg) was homogeneous by electrophoresis and we determined the N-terminal amino acid sequence up to ten residues, showing that it existed in the cryptic N-terminal domain of pGKL2-ORF2 (DNA polymerase) sequence.     

Genetically Programmed Regioselective Immobilization of Enzymes in Biosilica Microparticles

Diatoms are single‐celled microalgae that produce a large variety of hierarchically porous, silica‐based microparticles as cell wall material. The presence of genetically encoded silica nanopatterns endows the biosilica with favorable properties for a wide range of applications including catalysis, chemical sensing, photonics, and drug delivery. Enhancing the performance of diatom biosilica requires i) a better understanding of the structure–property relationship in this material, and ii) methods that enable the manipulation of the biosilica structure and properties in a targeted manner. Here, genetic engineering of the diatom Thalassiosira pseudonana is employed to immobilize enzymes (glucose oxidase and horseradish peroxidase) into structurally distinct regions of the biosilica, which are termed valves and girdle bands. Remarkably, glucose oxidase in girdle bands exhibits >3‐fold higher catalytic activities compared to its location in valves. It is demonstrated through enzyme accessibility studies, protein engineering, and genetic engineering of biosilica morphology that the divergent enzyme activities are caused by the differences in the inherent silica nanopatterns of valves and girdle bands. This work highlights the importance of silica nanoscale architecture for the activity of immobilized enzymes and provides unprecedented tools for the biotechnological production of silica microparticles with tailored catalytic activities and anisotropic functionalities.     

SOME BARLEY GRAIN AND GREEN MALT PROPERTIES AND THEIR INFLUENCE ON MALT HOT-WATER EXTRACT: II. PROTEIN,PROTEINASE AND MOISTURE

This paper continues the study of variation between varieties in some properties of barley and malt and examines protein-related characters and moisture uptake. Initial rate of moisture uptake was more closely related to enzyme activities than maximum moisture content. Significant varietal variation was found in all characters and this variation was greater than environmental variation with the exception of grain nitrogen concentration. In the endosperm endopeptidase activity was the character most highly correlated with malt hot water extract (HWE). The combined influence of protein- and β-glucan-related characters was investigated and the relative influence of each group of characters on HWE varied in different sections of the grain. In the endosperm the protein- and β-glucan-related characters accounted for 30% and 60% of the variation in HWE respectively.     

Utilisation of free and protein-bound methionine sulphoxide by the chicken

The biological availability of free and protein-bound methionine sulphoxide (MSO) was examined in nine growth experiments with chickens. The source of protein-bound MSO was fish meals oxidised with hydrogen peroxide. Bound MSO in oxidised fish meals was equally well utilised by the chicken as was bound methionine in unoxidised fish meals when the meals were the sole protein sources in the diet. When used as supplements to a low-methionine diet, oxidised fish meals were slightly less well utilised than L -methionine and unoxidised meals at the highest supplementation levels. At a low level there was no difference. Free L -MSO was less well utilised than free L -methionine when added to a soya bean meal diet and when used in purified diets. In the latter cystine was found to improve the utilisation of MSO. High levels of MSO were found in muscle extracts of chickens even when no MSO was present in their diet.     

基才隐马尔可夫模型的蛋白质序列筛选算法

对蛋白质序列筛选算法进行了研究,针对蛋白质数据库中存在大量的冗余序列,提出了一种基于隐马尔可夫模型的蛋白质序列筛选算法。详细阐述了在蛋白质数据库中如何建立隐马尔可夫模型。对模型中主要参数的求解和估计给出了主要计算公式。然后利用所建立的模型对蛋白质数据库进行的序列筛选测试,测试结果表明本文设计的算法对同源蛋白质序列筛选精...     

Epitope-Imprinted Nanoparticles as Transforming Growth Factor-β3 Sequestering Ligands to Modulate Stem Cell Fate

Growth factors (GFs) are biomolecules with potent biological effects but inherent limitations hinder their potential as therapeutic agents and cell culture supplements in tissue engineering and regenerative medicine (TERM). Biomaterials that sequester endogenous GFs by affinity binding might circumvent such limitations and thus are being increasingly investigated. Here, molecularly imprinted nanoparticles (MINPs) are proposed as specific abiotic ligands for GFs. As a proof of concept, a conformational epitope of transforming growth factor-β3 (TGF-β3) is designed and surface imprinted onto polyacrylamide-based nanoparticles by inverse microemulsion polymerization. It is found that, depending on the polymerization mixture composition, MINPs can recognize and preferentially bind TGF-β3, either in noncompetitive assays or from a complex human fluid (platelet lysate). Substrates functionalized with MINPs are then used for 2D culture of adipose-derived stem cells. Remarkably, gene and protein expression profiles show a marked upregulation of SOX-9, suggesting activation of TGF-β3 signaling pathways without requiring supplementation with exogenous GF. Likewise, culturing these cells in pellets incorporating MINPs previously incubated with platelet lysate results in higher collagen II-rich matrix deposition, compared to pellets incorporating non-imprinted nanoparticles. In summary, results suggest MINPs can be used as cost-effective, stable, and scalable alternative abiotic GF ligands to guide cell fate in TERM applications.     

低强度He-Ne激光照射水稻的显微拉曼散射研究

介绍了用显微拉曼研究经低强度He-Ne激光照射。并在均匀磁场中处理过的水稻的结果。并与未经处理水稻的拉曼光谱进行了比较。基本依据是激光对生物分子的共振激发作用理论。从实验结果看．其间的谱线有一定差异，表明激光照射和均匀磁场处理，有可能改变水稻的遗传特性。     

Water Vapor Permeability of Whey Protein Emulsion Films as Affected by pH

The water vapor permeability (WVP) of whey protein isolate-beeswax emulsion films was investigated as related to pH. Lower WVP was observed for films cast from solutions at pH 7.0. When pH of the film-forming solution was lowered, resulting film WVP increased. At the isoelectric point, WVP was the highest. As pH of the emulsion approached pI, a sharp change in viscosity occurred due to an increase in protein aggregation. This increase in viscosity probably lowered lipid mobility and reduced interconnectivity among lipid droplets, resulting in the higher WVP. For minimum WVP, such films should be applied at pH different from pI.     

Starch Retrogradation and Texture of Cooked Milled Rice During Storage

The effect of storing cooked Bengal and Cypress milled rice at -13, 3, 20, and 36 °C on texture and degree of starch retrogradation was investigated. Cooked rice firmness increased, while stickiness decreased, during storage at -13 and 3 °C. Starch retrogradation, measured with a differential scanning calorimeter, was observed for both cultivars during storage at -13 and 3 °C, but not at 36 °C. At 20 °C, retrogradation occurred in Cypress, but not in Bengal. Starch retrogradation showed positive linear trends with firmness for both cultivars at all storage temperatures (R²= 0.80) and with stickiness for Bengal stored at -13 and 3 °C and for Cypress stored at 3 and 20 °C (R2 = 0.88).     

大豆蛋白的吸水和持水性能

对大豆蛋白的吸水和持水性能及其影响因素进行了论述,大豆蛋白制品吸水能力的差别很小,一般为 ４０ ｇ 水／１００ ｇ 蛋白～６０ ｇ 水／１００ ｇ 蛋白。大豆蛋白制品的持水能力差别很大,约为１３０ ｇ 水／１００ ｇ 蛋白～６２５ ｇ 水／１００ ｇ 蛋白,持水性能在本质上是蛋白分子物理截留水的能力,其影响因素包括蛋白分子大小、形状、空间、构象等。高分子物理方法是一种新的研究方法,对这个方法在大豆蛋白吸水及持水性能方面的应用进行了讨论。