Peptide formation in the prebiotic era: thermal condensation of glycine in fluctuating clay environments

As geologically relevant models of prebiotic environments, systems consisting of clay, water, and amino acids were subjected to cyclic variations in temperature and water content. Fluctuations of both variables produced longer oligopeptides in higher yields than were produced by temperature fluctuations alone. The results suggest that fluctuating environments provided a favorable geological setting in which the rate and extent of chemical evolution would have been determined by the number and frequency of cycles.     

Evidence for crystalline water and ammonia ices on Pluto's satellite charon

Observations have resolved the satellite Charon from its parent planet Pluto, giving separate spectra of the two objects from 1.0 to 2.5 micrometers. The spectrum of Charon is found to be different from that of Pluto, with water ice in crystalline form covering most of the surface of the satellite. In addition, an absorption feature in Charon's spectrum suggests the presence of ammonia ices. Ammonia ice-water ice mixtures have been proposed as the cause of flowlike features observed on the surfaces of many icy satellites. The existence of such ices on Charon may indicate geological activity in the satellite's past.     

中性蛋白酶分步酶解花生分离蛋白制备花生短肽的研究

【目的】为了充分利用花生榨油之后的副产物,提高产品附加值,建立花生短肽制备工艺,研发功能性花生短肽产品。【方法】通过比较酶种类、底物浓度、酶解温度、酶解时间对水解度与短肽得率的影响,采用二次回归正交旋转组合设计优化分步酶解制备花生短肽的最佳工艺。【结果】中性蛋白酶分步酶解花生分离蛋白制备短肽的最佳工艺参数为：Neutrase水解花生分离蛋白2.04 h后加入Protamex继续酶解1.96 h,Neutrase添加量为5 200 U•g-1底物,Protamex添加量为422.32 U•g-1 底物,水解温度44.83℃,底物浓度8%,在此条件下,短肽得率为83.93%,水解度为38.25%,花生短肽纯度为93.85%±0.44%。经高效液相色谱测定,分子量小于1 000 D的水解产物占98.88%。【结论】采用Neutrase与Protamex分步酶解花生分离蛋白制备花生短肽,与现有碱性蛋白酶酶解制备花生短肽方法相比,避免了后续脱盐步骤,简化了工艺,且具有制备条件温和,DH和TCA-NSI高,纯度高,分子量集中分布于1 000 D以下等特点。     

Traffic jams reduce hydrolytic efficiency of cellulase on cellulose surface

A deeper mechanistic understanding of the saccharification of cellulosic biomass could enhance the efficiency of biofuels development. We report here the real-time visualization of crystalline cellulose degradation by individual cellulase enzymes through use of an advanced version of high-speed atomic force microscopy. Trichoderma reesei cellobiohydrolase I (TrCel7A) molecules were observed to slide unidirectionally along the crystalline cellulose surface but at one point exhibited collective halting analogous to a traffic jam. Changing the crystalline polymorphic form of cellulose by means of an ammonia treatment increased the apparent number of accessible lanes on the crystalline surface and consequently the number of moving cellulase molecules. Treatment of this bulky crystalline cellulose simultaneously or separately with T. reesei cellobiohydrolase II (TrCel6A) resulted in a remarkable increase in the proportion of mobile enzyme molecules on the surface. Cellulose was completely degraded by the synergistic action between the two enzymes.     

大豆蛋白质水解物——功能性低聚肽物质的开发研究

概述了大豆功能性低聚肽物质的分子组成，理化特性，生理功能，营养特性及功能性低聚肽物质的制备，苦味去除及其应用。     

高纯度大豆低聚肽药代动力学与急性毒性试验

研究了以“高温豆粕”为原料生产的高纯度大豆低聚肽在长白猪体内的药代动力学。结果表明:灌服后5 min进入血液,达峰时间10 min,半衰期为12 h。高纯度大豆低聚肽在最大给药剂量(按体重)30 g/kg时,无中毒现象出现,未测出半数致死量。急性毒性试验证明高纯度大豆低聚肽无毒。     

Composition and physical properties of Enceladus' surface

Observations of Saturn's satellite Enceladus using Cassini's Visual and Infrared Mapping Spectrometer instrument were obtained during three flybys of Enceladus in 2005. Enceladus' surface is composed mostly of nearly pure water ice except near its south pole, where there are light organics, CO2, and amorphous and crystalline water ice, particularly in the region dubbed the "tiger stripes." An upper limit of 5 precipitable nanometers is derived for CO in the atmospheric column above Enceladus, and 2% for NH3 in global surface deposits. Upper limits of 140 kelvin (for a filled pixel) are derived for the temperatures in the tiger stripes.     

羊奶干酪成熟期间蛋白质降解的研究

通过对羊奶干酪成熟９０ｄ内蛋白质降解的研究发现：水溶性氮（ＷＳＮ）和非蛋白氮（ＮＰＮ）在干酷成熟初期变化较大。游离氨基酸（ＦＡＡ）主要由丙氨酸（Ａｌａ）、蛋氨酸（Ｍｅｔ）、赖氨酸（Ｌｙｓ）、组氨酸（Ｈｉｓ）、谷氨酸（Ｇｌｕ）和亮氨酸（ｌｅｕ）等６种氨基酸构成。在蛋白质降解产物中，成熟初期主要是可溶性多肽类，后期寡肽含量较高。     

Coupled ferric oxides and sulfates on the Martian surface

The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) orbital data, we demonstrate that crystalline hematite deposits are associated with layered sulfates in other areas on Mars, implying that Meridiani-like ground water systems were indeed widespread and representative of an extensive acid sulfate aqueous system.     

Chiral-selective aminoacylation of an RNA minihelix

Amino acids in natural proteins have a chiral, asymmetric center at the alpha carbon that is of the L-configuration. The sugar backbone of natural RNAs are also homochiral, but of the D-configuration. Because protein synthesis requires the aminoacylation of RNA, it is this step that could have provided chiral selectivity. Here we show that an RNA minihelix was aminoacylated by an aminoacyl-phosphate-D-oligonucleotide with a clear preference for L- as opposed to D-amino acids. A mirror-image RNA system showed the opposite selectivity. These results suggest the possibility that the selection of L-amino acids for proteins was determined by the stereochemistry of RNA.     

Surface order and stability of langmuir-blodgett films

Angstrom-resolution atomic force microscope images of Langmuir-Blodgett monolayers and multilayers of cadmium arachidate in air and under water show a dramatic change from a disordered arrangement to a crystalline lattice by the addition or removal of a single layer of molecules. The disordered surface is less stable than the ordered one to mechanical stresses such as atomic force microscopy tip forces or at the air-water contact line during contact angle measurements. The difference in the degree of order in the alkyl chains is attributed to the strong attractive interaction between headgroups in the presence of the divalent cation.     

Surface structure of polymers: glancing-angle electron diffraction study of polyethylene

The surface regions of polyethylene nucleated and crystallized in contact with both a high-energy surface (gold) and a low-energy surface (fluorinated ethylene-propylene copolymer Teflon) have been examined by means of glancing-angle electron-diffraction techniques. Examination of these surfaces has been confined to a maximum depth of 120 angstroms. The surface region of the polyethylene generated in contact with the gold is considerably more crystalline than the surface generated in contact with the fluorinated ethylene-propylene copolymer Teflon. These results tend to corroborate recent wettability and infrared studies. Apparently, the surface structure of polyethylene is highly dependent upon the method of preparation.     

梅子苦味寡肽及氨基酸之萃取、分离与鉴定(英文)

先将梅子破碎、冷冻干燥后,以溶剂萃取肽,再将之浓缩,将萃取液经凝胶过滤分离肽后,以高效液相层析仪将各组分进一步分离得肽．由凝胶过滤分离出之肽,以官能品评找出具有苦味之部分,结果显示３个梅子品种在第１９～２８试管中具有苦味;经以高效液相层析仪分析,结果其肽含量与苦味之强弱呈正相关．由杏仁苷阈值试验得知梅子中所含有之杏仁苷尚未达到苦味阈值之要求,由此可证明其中具有其他苦味寡肽及游离氨基酸之存在     

梅子苦味寡肽及氨基酸之萃取、分离与鉴定

先将梅子破碎、冷冻干燥后,以溶剂萃取肽,再将之浓缩,将萃取液经凝胶过滤分离肽后,以高效液相层析仪将各组分进一步分离得肽。由凝胶过滤分离出之肽,以官能品评找出具有苦味之部分,结果显示３个梅子品种在第１９￣２８试管中具有苦味;经以高效液相层析仪分析,结果其肽含量与苦味之强弱呈正相关。由杏仁苷阈值试验得知梅子中所含有之杏仁苷尚未达到苦味阈值之要求,由此可证明其中具有其他苦味寡肽及游离氨基酸之存在。     

Surface crystallization in a liquid AuSi alloy

X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au82Si18, at temperatures above the alloy's melting point. Surface-induced atomic layering, the hallmark of liquid metals, is also found below the crystalline monolayer. The layering depth, however, is threefold greater than that of all liquid metals studied to date. The crystallinity of the surface monolayer is notable, considering that AuSi does not form stable bulk crystalline phases at any concentration and temperature and that no crystalline surface phase has been detected thus far in any pure liquid metal or nondilute alloy. These results are discussed in relation to recently suggested models of amorphous alloys.     

Triacontanol: a new naturally occurring plant growth regulator

Alfalfa meal and chloroform extracts of the meal have increased the growth and yield of several plant species. A crystalline substance isolated from the active fraction of alfalfa meal increased the dry weight and water uptake of rice seedlings when sprayed on the foliage or applied in nutrient culture. The substance was identified as triacontanol by mass spectrometry. Sprays containing this compound also increased the growth of corn, and barley grown in soil. Authentic triacontanol produced a similar response over a wide range of concentrations on rice grown in nutrient cultures and tomatoes grown in soil.     

波涌灌土壤物理性质变化

根据大量田间波涌灌实验分析,对地表土壤物理性质变化进行了研究,证实了土壤容重的变化对波涌灌节水性有重要作用。同时也认识到,波涌灌与传统连续灌地表土壤都可以形成致密层,二者的结构相似。但重要的是波涌灌利用这种致密层的形成和发展,改善了入渗特性和地表水流特性,从而达到节水的效果。     

结晶纤维素降解酶的研究进展

纤维素的结晶区是纤维素酶降解纤维素效率不高的制约因素.在纤维素生物降解的基础上,从产结晶纤维素酶的微生物,酶的作用机理,酶的基因工程与蛋白工程,以及结晶纤维素酶的研究前景等方面对结晶纤维素的降解作了综合评述.     

河北平原水环境状况初步研究

系统调查研究了河北平原水资源的条件和利用状况，包括地表水资源，地下潜水资源和地下深水资源，重点研究了由于各种水资源过量开采所造成的河北平原水环境恶化，主要包括地表水资源的污染，萎缩和由此产生的环境问题；地下潜水资源的过量开采所造成的诸多地质灾害及深层地下水超量开采造成的水位大幅度下降和地面下沉等，针对河北平原的特点和目前存在的突变问题提出了合理利用河北平原水资源和保护其水环境急需解决的问题。     

不同酶解法水解豆粕蛋白的比较研究

研究不同的酶解方式对豆粕蛋白酶解过程及产物的影响。采用Alcalase蛋白酶、Protex.7L蛋白酶对豆粕蛋白进行单酶、双酶同步和双酶分步水解,以水解度、蛋白质利用率、多肽得率、寡肽得率为指标对酶解过程进行分析。结果表明采用先加Alcalase蛋白酶后加Protex.7L蛋白酶组合水解豆粕蛋白的效果最佳,最终水解液中水解度可达23.5%,蛋白质利用率、多肽得率、寡肽得率分别为68.7%、51.0%、21.4%。双酶分步水解的效果优于单酶水解和双酶同步水解;酶的加入顺序对豆粕的酶解过程有一定的影响。