生物活性肽——蛋氨酸脑啡肽治疗白血病一例报告

蛋氨酸脑啡肽是内源性阿片样物质。它是由5个氨基酸残基组成的多肽,其第5位氨基酸残基为蛋氨酸。通过抽取病人静脉血,分离淋巴细胞,进行体外扩增激活,然后回输患者体内,患者外周血白细胞计数为3．6×10^9／L,血红蛋白122g/L,血小板116×10^9／L,异常淋巴细胞消失,幼粒细胞消失。骨髓象示粒细胞系统、红细胞系统增生活跃,各阶段细胞比值及形态大致正常;淋巴细胞比值减低,形态正常;造血功能恢复。由此可见,蛋氨酸脑啡肽体外激活免疫系统并回输体内作为一种新的治疗白血病的方法,具有广泛的应用前景。     

固有无序蛋白与蛋白质相互作用位点残基特征分析

本文对固有无序蛋白(IDPs)与其他蛋白质相互作用位点残基特征进行了研究.首先在数据库中选出满足条件的109条IDPs蛋白质链及与其他配体蛋白形成的299个IDPs-蛋白质复合物,然后提取复合物中作为相互作用位点的IDPs-蛋白质残基.这109条IDPs链中共含有50 031个氨基酸残基,其中处于作用位点的残基有4 822个.通过分析发现,20种氨基酸在形成IDPs-蛋白质相互作用位点残基时具有不同的倾向性,根据形成作用位点残基的倾向性,20种氨基酸可分成三大类:倾向型氨基酸(ILE、LEU、ARG、PHE、TYR、MET、TRP)、中间型氨基酸(GLN、GLU、THR、LYS、VAL、ASP、HIS)、非倾向型氨基酸(PRO、SER、GLY、ALA、ASN、CYS).研究结果还进一步表明,不同氨基酸在有序区域与无序区域形成IDPs-蛋白质作用位点残基的倾向性不同.其中,氨基酸TRP、LEU、ILE、CYS在有序和无序区域形成作用位点残基的差异性尤为明显,而氨基酸GLU、PHE、HIS、ALA则基本没有多大差别.对IDPs-蛋白质相互作用位点残基理化特征进行分析发现:疏水性强、侧链净电荷量较少、极性较小、溶剂可及性表面积较大、侧链体积较大、极化率较大的氨基酸比较倾向于形成作用位点残基.主成分分析结果显示,残基的极化率、侧链体积和溶剂可及表面积对作用位点残基影响最大.     

生物活性肽——蛋氨酸脑啡肽的免疫

源自肾上腺前脑啡肽原的具有吗啡样生物活性的内源性神经肽蛋氨酸脑啡肽(methionine enkephalin,MENK),由５个氨基酸残基Tyr Gly Gly Phe Met组成,与G蛋白偶联的７次跨膜特异性受体结合后发挥不同的生物学功能。目前,对蛋氨酸脑啡肽的作用及其机制研究已经取得了很大进展。本文就MENK对于免疫系统的调节及其对肿瘤、自身免疫病、艾滋病等免疫系统相关疾病的治疗作用予以综述。     

N-乙酰鸟氨酸脱酰基酶活性位点的构成研究

目的:用生物信息学软件预测出N-乙酰鸟氨酸脱酰基酶的活性中心的金属离子结合位点.方法:选用DEPC、WRK、PMSF、NBS、DTNB 5种化学试剂选择性修饰N-乙酰鸟氨酸脱酰基酶中组氨酸、天冬氨酸、谷氨酸、丝氨酸、色氨酸和半胱氨酸;同时考察Co2、Fe3 、Mg2 、Mn2 、ZN2 、Ni2 、Cu2 等金属离子对酶活性的影响.结果:在DEPC、WRK修饰后,酶的活力明显下降,而PMSF、NBS、DTNB对酶的活力影响不大;说明组氨酸和酸性氨基酸为酶活性中心的必需氨基酸,而丝氨酸残基、色氨酸残基、半胱氨酸残基不参与酶活性中心的组成;Co2 对酶反应有促进作用,验证了生物信息学的预测结果;底物N-乙酰-D,L-蛋氨酸对酶有较好的保护作用,保护作用随浓度增加而增加.结论:本研究为深入研究酶结构与功能的关系提供实验依据,为N-乙酰鸟氨酸脱酰基酶的工业应用提供理论参考.     

烟草DREBP转录因子结合DRE元件的关键氨基酸

从烟草品种本塞母氏中分离出2条DREB类转录因子基因,分别命名为NbDREB1和 NbDREB2.根据测序结果推导出的氨基酸序列分析显示,NbDREB1和NbDREB2都具有典型的AP2/EREBP转录因子家族EREBP亚族A类特征.酵母单杂交结果显示,它们都不具有激活功能.连接pGADT7反式激活载体形成融合基因表达结果显示,NbDREB1能与DRE顺式作用元件结合,NbDREB2则不能.比较NbDREB1和NbDREB2的AP2区,发现两者的第2和49位氨基酸残基不同.对NbDREB2的第2位氨基酸残基N点突变为Y,NbDREB2也显示出与DRE顺式元件结合的活性,表明烟草DREB转录因子的AP2区第2位氨基酸残基Y是识别及结合DRE顺式作用元件必需的氨基酸残基.     

扩展青霉PF898碱性脂肪酶cDNA的克隆及序列分析

扩展青霉 (Penicilliumexpansum)PF898可产生一种具有工业价值的碱性脂肪酶 (PEL) .在测定了其N端 12个氨基酸残基序列的基础上 ,通过RT PCR、5′RACE、基因克隆及序列测定 ,获得了PEL完整的cDNA序列 (GenBank登录号为AF2 84 0 6 4 ) .cDNA全长 10 5 0bp ,包括PEL编码区、3′非翻译区和部分 5′非翻译区基因的序列 .编码区cDNA由 85 5个碱基组成 ,编码 1个由 2 85个氨基酸残基组成的酶蛋白 ,其信号肽及前肽部分由 2 7个氨基酸残基组成 ,成熟肽部分由 2 5 8个氨基酸残基组成 .根据氨基酸组成推导该脂肪酶蛋白的分子量为 2 7 3kD .该脂肪酶的氨基酸序列 130～ 134位上有各类脂肪酶中普遍存在的G X S X G保守序列     

马槟榔甜味蛋白的研究Ⅱ．甜蛋白Ⅱ和甜蛋白Ⅰ的比较

从马槟榔（Capparis masaikai Levl．）种子分离鉴定了二种甜蛋白：甜蛋白I（mabinlinⅠ或MaⅠ）分子量MWll600,等电点PⅠll.8;甜蛋白Ⅱ（mabinlinⅡ或MaⅡ）MW 10400,PⅠll.3。另一组分mabinlinⅡ MW10200,pl 11.8,可能是提取过程产物。MaⅡ有84个氨基酸残基,比MaⅠ少15个。它们有80个氨基酸残基是共同的,都是缺丝氨酸和蛋氨酸的单一多肽链。MaⅠ还缺赖氨酸和酪氨酸。测不出有自由SH基。在8 M尿素中用巯基乙醇还原处理,两种甜蛋白分子都可转变为二聚体而失去甜味。     

蛋氨酸调控动物主要生理功能的机制

蛋氨酸是动物机体的必需氨基酸,同时也是饲粮中的限制性氨基酸.蛋氨酸可作为底物参与蛋白质的合成,同时也可作为甲基供体参与DNA, RNA和蛋白质等的甲基化,或通过转巯基途径发挥抗氧化功能以及参与多胺的形成.这些代谢途径对动物的生产性能、抗氧化能力、免疫功能以及肠道健康等方面有着重要的调控作用.本文对近年来关于蛋氨酸调控生理功能的机制进行综述,以期为蛋氨酸代谢机制的研究及科学应用提供参考.     

615小鼠血红蛋白α链的氨基酸组成及个别肽段的氨基酸序列

用CM-Cellulose-23柱层析分离纯化了615小鼠珠蛋白α链,测定其N端氨基酸残基为缬氨酸.615小鼠珠蛋白α链含有141个氨基酸残基,其中19个亮氨酸残基,10个组氨酸残基,9个缬氨酸残基,上述氨基酸残基的数目与文献中其亲本C₅₇BL不同.用胰蛋白酶水解615小鼠珠蛋白α链,发现有不溶性的‘核心’和可溶性的酶解片段.其中一个酶解肽段从N端数第8位氨基酸残基发生了突变,由亲本的缬氨酸变为亮氨酸.     

羟基蛋氨酸及其钙盐的合成研究进展

羟基蛋氨酸钙是复方α-酮酸片中一个重要成分,可防止氨基酸缺乏和改善代谢紊乱,对肾功能衰竭具有一定的疗效,并对钙代谢和继发性甲状旁腺功能亢进都具有益作用,同时也是重要的有机合成、药物合成及生物合成中间体.本文对近年来羟基蛋氨酸及其钙盐的合成方法进行了综述.重点介绍了氰醇水解法、蛋氨酸转化法、酮酸转化法、酮醇氧化法、氰代磷酸二乙酯法和α-羟基-γ-丁内酯法等在羟基蛋氨酸及其钙盐合成中的应用.     

Multiple Factors Influencing the In Vitro Release of [Met5]-Enkephalin from Rat Hypothalamic Slices

This study examined several in vivo and in vitro factors which influence the release of [Met5]-enkephalin (Met-ENK) from male rat hypothalamic slices superfused in vitro. Met-ENK release was significantly stimulated by corticotropin-releasing hormone (CRH; 10(-12)-10(-8) M), an effect which was abolished in the presence of the CRH-receptor antagonist, alpha-helical CRF9-41 (10(-6) M). The amount of Met-ENK release diminished with time in experiments in which the slices were continuously exposed to CRH. The opioid receptor antagonist naloxone (10(-6) M) stimulated Met-ENK release, even in the presence of the Na+ -channel blocker tetrodotoxin (10(-6) M), a result indicating presynaptic opioid feedback inhibition of Met-ENK release. The role of gonadal steroids in the control of Met-ENK release in vitro was also examined. It was found that the basal and CRH-induced release of Met-ENK was not changed 1 week after castration. However, a significant increase in the basal release of this peptide was observed 4 weeks after gonadectomy, and the Met-ENK-releasing efficacy of CRH was found to be reduced. The Met-ENK content of hypothalami from 1-week castrates was not significantly changed from control levels, but was significantly reduced in those from 4-week castrates. These long-term effects of castration could be overcome by the subcutaneous implantation of testosterone-containing capsules at the time of castration.     

Characterization of Delta-Sleep-Inducing Peptide-Evoked Release of Met-Enkephalin from Brain Synaptosomes in Rats

Delta-sleep-inducing peptide (DSIP) stimulates the release of Met-enkephalin (Met-ENK) from superfused slices of the rodent lower brainstem in vitro. In our present study, DSIP (10(-10)-10(-9) M) induced a significant release of Met-ENK from medullary synaptosomes of rats. This DSIP-evoked release of Met-ENK was Ca2+ dependent and tetrodotoxin (TTX) insensitive. Furthermore, DSIP (10(-11)-10(-9) M) significantly increased 45Ca2+ uptake in medullary synaptosomes. These results demonstrate that DSIP acts directly on the nerve endings of Met-ENK-containing neurons to release this pentapeptide by generating a Ca2+ influx into these neurons. Effects of DSIP on Met-ENK release in other discrete brain regions were also studied. Significant DSIP-evoked Met-ENK release from synaptosomes was observed in the cortex, hypothalamus, and midbrain (at concentrations of 10(-10) and 10(-9) M) and in the hippocampus and thalamus (only at 10(-9) M), but not in the striatum. In the hypothalamus, the release of Leu-enkephalin from its synaptosomes was slightly, but not significantly, enhanced by DSIP (10(-10)-10(-8) M). Our findings demonstrate that DSIP triggered a Ca2+ influx in nerve endings to induce a subsequent release of Met-ENK from neurons in only certain brain regions.     

Co-existence of the enkephalinergic system and the melanotropinergic system in the rat duodenum shown by immunohistochemistry

The immunohistochemical distribution of alpha-melanotropin (alpha-MSH) and Met-enkephalin (Met-ENK) immunoreactivities in the rat duodenum was examined by using immunofluorescence microscopy. Alternately staining of adjacent frozen serial sections with specific antisera directed to alpha-MSH or Met-ENK revealed that within a subpopulation of myenteric plexus perikarya alpha-MSH immunostaining co-exists with that of Met-ENK. Some myenteric plexus nerve fibres also contain both Met-ENK and alpha-MSH immunoreactivity. These findings might indicate that the genes encoding for the precursors of melanotropins (the pro-opiomelanocortin precursor) and enkephalin (the pro-enkephalin precursor) are generated from a common, large and single ancestor gene which remained conserved during evolution in the rat enteric nervous system.     

Met-enkephalin involvement in morphine-modulated peritonitis in swiss mice

Morphine coinjection with zymosan inhibits pain and leukocyte accumulation during peritonitis in several strains of mice, and affects systems of endogenous opioids. Present investigations focus on Met-enkephalin (Met-ENK) in the inflamed peritoneal cavity and brain centers of Swiss mice. Males of Swiss mice were IP injected with zymosan or zymosan supplemented with morphine. At the selected time points the peritoneal leukocytes were counted and the Met-ENK level was measured in exudatory fluid and leukocytes, striatum, hypothalamus, and pituitary gland. The Met-ENK content in peritoneal fluid rised sharply after zymosan injection, which corresponded with its decline in exudatory leukocytes, hypothalamus, and striatum. Morphine coinjection enhanced intraperitoneal accumulation of Met-ENK and its release from exudatory leukocytes, but inhibited its early fluctuations in hypothalamus and striatum. Effects of morphine-modulated inflammation on the Met-ENK system lasted longer than 7 days.     

Evidence for the presence of enkephalins in the heart

Extracts of guinea pig hearts were subjected to high performance liquid chromatography (HPLC) and the eluted fractions monitored by radioimmunoassays (RIA) for their content of leucine⁵-enkephalin (Leu-ENK) and methionine⁵ enkephalin (Met-ENK). Distinct peaks of both Leu-ENK and Met-ENK immunoreactivity were found corresponding to the position of synthetic Leu-ENK and Met-ENK respectively. The ratio of Leu-ENK to Met-ENK content was about 1:4. Chemical sympathectomy with 6-hydroxydopamine (6-OH-DA) produced a dramatic fall in noradrenaline content of the heart by more than 99%, whereas the concentration in Leu-ENK was reduced by only 70%. The Leu-ENK content of the adrenal glands was not affected by this treatment. These observations point to an enkephalinergic innervation of the heart which appears to be mainly of sympathetic origin. The results suggest the participation of enkephalins in cardiac reflex mechanisms.     

Cardiovascular activities of intravenous methionine-enkephalin-Arg6-Phe7 and methionine-enkephalin-Arg6-Gly7-Leu8 in the conscious dog

The preproenkephalin A molecule from the adrenal medulla contains the opioid peptides methionine-enkephalin (Met-ENK), leucine-enkephalin (Leu-ENK), methionine-enkephalin-Arg6-Phe7 (heptapeptide), and methionine-enkephalin-Arg6-Gly7-Leu8 (octapeptide). In the conscious, chronically instrumented dog, Met-ENK and Leu-ENK simultaneously increase heart rate and systemic arterial pressure following intravenous administration. In 19 of 23 dogs, heptapeptide produced a response identical to Met-ENK and Leu-ENK, which was inhibited by naloxone but unaffected by the dipeptidyl carboxypeptidase inhibitor SQ20881. However, in four dogs, heptapeptide produced only a fall in systemic pressure associated with an increase in heart rate despite characteristic Met-ENK responses in the same dogs; naloxone did not appear to alter this hypotensive response. Octapeptide produced slight increases in systemic pressure and heart rate. These data suggest that heptapeptide may possess intrinsic cardiovascular activity at opiate receptors; however, in certain dogs, non-opiate mechanisms, perhaps histamine release, may predominate.     

氨基酸Schiff碱金属配合物的研究进展

本文概述了近年来国内外在氨基酸Ｓｃｈｉｆ碱金属配合物领域的研究进展。简介了它们的合成方法和在金属离子分析、药物化学、生物模拟、氨基酸的合成及拆分上的应用。     

氨基酸Schiff碱及其金属配合物的抑菌抗癌活性的研究进展

氨基酸Ｓｃｈｉｆｆ碱及其金属配合物具有良好的生理、生物活性,本文就近年来国内外在氨基酸Ｓｃｈｉｆ碱及其金属配合的抑菌抗癌活性的研究进展方面进行了综述     

氨基酸转运体在肿瘤代谢中的研究进展

代谢重编程是肿瘤的重要特征,是指肿瘤细胞为满足其快速增殖的生物合成与能量需求,对其糖代谢、脂代谢以及氨基酸代谢等代谢路径进行的重编程,以维持增长速度以及补偿能量代谢所造成的氧化还原压力。虽然不同的癌症代谢变化不同,但有些特征是所有癌症共有的,氨基酸代谢重编程是其中一个重要的特征。氨基酸进出细胞需要氨基酸转运体的协助,因而在肿瘤细胞中多种特定的氨基酸转运体均过表达。靶向氨基酸转运体通过影响肿瘤细胞的氨基酸代谢从而达到抗肿瘤的目的,是目前抗肿瘤药物的研究热点之一。主要介绍了几种在肿瘤代谢中发挥重要作用的氨基酸转运体以及靶向氨基酸转运体抗肿瘤治疗的研究进展及相关作用机制,旨在了解氨基酸转运体在抗肿瘤研究中的作用,以期促进靶向氨基酸转运体抗肿瘤药物的发展。     

氨基酸转运载体LAT1研究进展

哺乳动物氨基酸的跨膜运输由多种氨基酸转运载体蛋白介导,其中L型氨基酸转运载体1（LAT1）属于L系统,主要转运大分子支链氨基酸和芳香族中性氨基酸。研究表明,LAT1广泛存在于哺乳动物肝脏、骨髓、大脑、胎盘、心脏和睾丸组织中,LAT1在恶性肿瘤中大量表达,对其不断的增殖起着重要的作用。目前国内对氨基酸转运载体LAT1的研究仍是空白,鉴于LAT1的研究在医学、营养等生命科学领域的研究意义,本文就氨基酸转运载体蛋白LAT1的表达、调节及其相关研究进展作一综述。