Amino acids from ultraviolet irradiation of interstellar ice analogues

Amino acids are the essential molecular components of living organisms on Earth, but the proposed mechanisms for their spontaneous generation have been unable to account for their presence in Earth's early history. The delivery of extraterrestrial organic compounds has been proposed as an alternative to generation on Earth, and some amino acids have been found in several meteorites. Here we report the detection of amino acids in the room-temperature residue of an interstellar ice analogue that was ultraviolet-irradiated in a high vacuum at 12 K. We identified 16 amino acids; the chiral ones showed enantiomeric separation. Some of the identified amino acids are also found in meteorites. Our results demonstrate that the spontaneous generation of amino acids in the interstellar medium is possible, supporting the suggestion that prebiotic molecules could have been delivered to the early Earth by cometary dust, meteorites or interplanetary dust particles.     

Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues

The delivery of extraterrestrial organic molecules to Earth by meteorites may have been important for the origin and early evolution of life. Indigenous amino acids have been found in meteorites-over 70 in the Murchison meteorite alone. Although it has been generally accepted that the meteoritic amino acids formed in liquid water on a parent body, the water in the Murchison meteorite is depleted in deuterium relative to the indigenous organic acids. Moreover, the meteoritical evidence for an excess of laevo-rotatory amino acids is hard to understand in the context of liquid-water reactions on meteorite parent bodies. Here we report a laboratory demonstration that glycine, alanine and serine naturally form from ultraviolet photolysis of the analogues of icy interstellar grains. Such amino acids would naturally have a deuterium excess similar to that seen in interstellar molecular clouds, and the formation process could also result in enantiomeric excesses if the incident radiation is circularly polarized. These results suggest that at least some meteoritic amino acids are the result of interstellar photochemistry, rather than formation in liquid water on an early Solar System body.     

阿维巴坦类似物的合成及抗菌活性研究

研究阿维巴坦类似物的合成及抗菌活性,以(2S, 5R)-6-苄氧基-7-氧-1,6-二氮杂二环[3.2.1]辛烷-2-甲酸乙酯(2)为原料,经还原和碘代,再与三氮唑缩合反应,经钯碳加氢脱保护和磺化反应后,得到阿维巴坦类似物1,结构经~1H NMR和MS表征确证。生物活性测试结果表明,类似物对铜绿假单胞菌和大肠杆菌较阿维巴坦有更好的抑菌活性,其中化合物1i最小抑菌浓度分别达到4和0.25μg/mL。     

氨基酸衍生物的电化学研究及碱性氨基酸的极谱测定

本文研究了多种氨基酸与水杨醛在碱性介质中的衍生化及其产物（席夫碱）的电化学行为。结果表明：席夫碱的生成和氨基酸的测定灵敏度受氨基酸的性质影响很大，碱性氨基酸能形成很好的极谐波，检测限低于１×１０－６ｍｏｌ／Ｌ，用此法测定了食品中的赖氨酸含量和血清中蛋白质总量，得到较满意的结果．     

星虫状海葵氨基酸和脂肪酸的组成与含量分析

分析了星虫状海葵的营养成分,干物质中的蛋白质和氨基酸含量分别为62．3％和51．9％;必需氨基酸占氨基酸总量的36．6％,氨基酸分为48。脂肪酸组成具有以下几个特点：26种脂肪酸组成;不饱和脂肪酸(UFA)含量为75．27％,高于饱和脂肪酸(SFA);不饱和脂肪酸中高度不饱和脂肪酸(HUFA)的含量(52．71％)较高;EPA和DHA的含量较高,分别为13．88％和10．98％。星虫状海葵是一种开发前景较好的海产品。