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1.
The crystal structure of thiamine pyrophosphate has been determined by a three-dimensional x-ray analysis. The conformation of the molecule in the crystalline state is determined by the formal charge distribution within the molecule which exists as a zwitterion with the negative pyrophosphate chain folded back over the positive, ring portion of the molecule. The oxygen atoms in the pyrophosphate group are in the staggered conformation when viewed along the phosphorus-phosphorus axis. Even though the pyrophosphate is present in this compound as the monoionized monoester, the configuration is the same as that present in the inorganic pyrophosphate ion. From a comparison of three different crystal structures containing the thiamine moiety and from studies with atomic models, it seems plausible that the basic molecular conformation observed in this crystal is maintained in the catalytically active molecule. Knowledge of the detailed crystal structure provides new insight into the biochemical mechanism of reactions catalyzed by thiamine pyrophosphate. 相似文献
2.
Extracts of tissue fluids from a patient with subacute necrotizing encephalomyelopathy inhibit thiamine pyrophosphate-adenosine triphosphate phosphotransferase of rat brain. Brain tissue from the patient, in contrast to normal brain tissue, contained essentially no thiamine triphosphate, although thiamine and its other phosphate esters were present in normal concentrations. These findings suggest a relation between this disease and thiamine triphosphate. 相似文献
3.
Thiamine release from nerve membranes by tetrodotoxin 总被引：3，自引：0，他引：3
Tetrodotoxin (3 x 10(-8) molar) promoted the release of thiamine from perfused rat and frog nerve preparations in a manner similar to other neuroactive drugs. When the rats were injected with thiamine labeled with sulfur-35, analyses of brain, spinal cord, and sciatic nerve homogenates revealed labeled thiamine in membrane, synaptosomes, and mitochondrial subfractions. However, on incubation of these fractions with tetrodotoxin, thiamine was released only from the membrane fragments. 相似文献
4.
通过实验进行了二苯酰硫胺素化学合成工艺及其有关特性的研究。确定了二苯酰硫胺素合成的工艺路线、条件和方法。检测了二苯酰硫胺素的实收率、含量、化学结构、热稳定性、水稳定性、脂溶性和安全性。结果表明，所合成出的二苯酰硫胺素完全符合现代食品加工业的要求。 相似文献
5.
Response to ethanol reduced by past thiamine deficiency 总被引：1，自引：0，他引：1
P R Martin E Majchrowicz E Tamborska C Marietta A B Mukherjee M J Eckardt 《Science (New York, N.Y.)》1985,227(4692):1365-1368
Ethanol-induced intoxication and hypothermia were studied in rats approximately 7 months after severe thiamine deficiency, when treated rats appeared to have recovered their physical health. Previously induced thiamine deficiency without prior ethanol exposure significantly decreased the area under the curve plotted for the concentration of ethanol in blood and also decreased behavioral impairment and hypothermia due to ethanol exposure. Pathophysiologic changes resulting from thiamine deficiency may contribute to both the pharmacodynamic and pharmacokinetic tolerance to ethanol in chronic alcoholics. 相似文献
6.
[目的]研究美拉德反应条件对鹅肉风味液的影响,为生产鹅肉风味香精提供理论参考。[方法]首先进行单因素试验,通过排序检验法筛选出适合进行响应面分析的美拉德反应参数,选择硫胺素添加量、半胱氨酸添加量、反应温度和反应时间4个因素进行BoxBehnken试验设计,通过响应面分析法获得最佳的美拉德反应条件。[结果]8个单因素中硫胺素添加量、鹅脂添加量、半胱氨酸添加量、反应时间等6个单因素对鹅肉风味有显著影响,根据F值排序,最终选择硫胺素添加量、半胱氨酸添加量、反应温度、反应时间4个单因素进行响应面分析试验。通过方差分析,确定所建立的二次回归模型为有效模型,通过该模型可求得美拉德反应制备鹅肉风味香精的最佳工艺条件为硫胺素1.09 g,半胱氨酸0.62 g,反应温度118.30℃,反应时间56.33 min。[结论]通过优化后的方法制备鹅肉风味液感官评价最高,达到4.186分。 相似文献
7.
The finding of abnormal estrogenic activity coupled with thiamine deficiency in cases of menorrhagia and uterine cancer suggests a possible etiological correlation between the dietary deficiency, the abnormal estrogen level, and the pathological lesion. The specific element deficient in these cases was thiamine, while the other B factors were normal. Preliminary report of the evidence is made in this small series while more extensive studies on a large series of cases are being pursued. Cornification in cytology smears was used to study estrogenic activity, since the present study was prompted by cytological findings; the method is simple, practical, and reasonably accurate. The urinary estimation measures only the amount excreted, and if liver impairment actually is present, the quantity excreted would not give a true index of the amount retained in the body. Further studies are being undertaken in which estrogenic, urinary, and cornification levels are being compared before and after thiamine administration in cases proven to be deficient. 相似文献
8.
[目的]实现企业在肌苷发酵生产中对酵母粉原料质量的评价,为肌苷发酵的控制奠定重要的方法学基础。[方法]将酵母粉经过高温高压并用盐酸提取,通过试验确定高效液相色谱法分离条件并测定硫胺素含量。[结果]采用Hypersil BDS C18色谱柱,紫外检测波长为254 nm;以0.02 mol/L pH 3的磷酸盐缓冲液为流动相,流速1.0 ml/min对提取液进行色谱测定,可以将硫胺素与其他成分有效分离。用0.1 mol/L HCl悬浮后在超声清洗器中振荡10 min混合均匀,然后于121℃高温高压下30 min离心可将酵母粉中的硫胺素充分释放出来。[结论]采用高效液相色谱法测定酵母粉中硫胺素含量,该方法快速、准确,测定结果可做为评价酵母粉质量的指标,对肌苷发酵有重要指导意义。 相似文献
9.
Reaction of thiochrome with with alpha-chloropropionic acid yields thiamine and acetaldehyde. The reaction seems to proceed by way of a zwitterion intermediate that undergoes decarboxylation and hydrolysis. The biological significance of the reaction cannot yet be evaluated. 相似文献
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11.
【目的】顶质体是存在于包括疟原虫和巴贝斯虫在内的顶复门寄生虫的一种细胞器,在病原体中,它主要承载类异戊二烯前体和脂肪酸合成途径,异戊二烯五碳结构是有机体合成多种化合物的结构基础,对有机体生命活动至关重要,例如,在哺乳动物中成为胆固醇和类固醇激素的基本结构,在植物中参与合成类胡萝卜素。且存在于顶质体的类异戊二烯前体合成途径对于病原体的生命活动至关重要且不存在于人类和哺乳动物机体,这使其成为近年来人们研究抗原虫药物的焦点。有学者发现利用特异性阻断类异戊二烯代谢途径的药物可治疗疟疾。1-脱氧-5-磷酸 D-木酮糖合成酶（DXS）为该途径中的第一个限速酶。因此,针对牛巴贝斯虫的1-脱氧-5-磷酸 D-木酮糖合成酶dxs基因进行克隆和序列分析,并对其进行真核表达和活性检测,以期获得具有活性的1-脱氧-5-磷酸 D-木酮糖合成酶,为进行针对该酶的特异性抑制剂的筛选奠定基础。【方法】首先采用反转录PCR技术从牛巴贝斯虫陕县株总RNA中扩增出DXS基因的全长cDNA,并对其进行克隆测序,对测序结果进行序列分析,将阳性克隆亚克隆至带荧光标签的真核表达载体,利用脂质体转染法将重组真核表达质粒转染至Hela细胞,利用倒置荧光显微镜观察转染细胞的表达情况,消化收集转染细胞,通过超声破碎后采用Western blot技术对DXS蛋白的表达情况进行检测,结合G418压力筛选以及有限稀释的方法对转染阳性细胞进行筛选,获得阳性单克隆细胞。在体外建立DXS酶反应体系,并利用液相质谱联用技术对表达产物的体外活性进行检测。【结果】扩增得到的DXS基因全长共2 061 bp,共编码686个氨基酸,与GenBank上T2Bo株相应基因相似性达到98.0%。利用生物信息学方法对该蛋白质的二级结构进行分析发现,该酶具有3个结构域,分别是焦磷酸硫胺素结合区域;焦磷酸硫胺素嘧啶环结合区域;转酮醇酶C端区域,该酶属于常见的TPP依赖蛋白酶家族。通过倒置荧光显微镜观察,转染重组质粒后的Hela细胞呈现绿色荧光,Western blotting结果显示融合绿色荧光蛋白的DXS酶大小约为102 kD,表明构建的真核表达重组质粒在Hela细胞中进行了正确的表达。通过结合G418加压和有限稀释法筛选得到稳定转染重组质粒PEGFG-DXS的阳性单克隆细胞。利用质谱技术检测到在细胞粗提物与反应混合物反应后的产物中有分子量与DOXP相同的产物存在,在阳离子模式下m/z=237,表明表达产物具有催化活性。【结论】成功的表达了具有活性的牛巴贝斯虫DXS酶,并对融合蛋白的活性进行了定性分析,为今后开展针对DXS酶的特异性化合物体外高通量筛选研究提供了材料。对研究针对DXS为靶标的抗原虫药物具有重要意义,为深入研究该酶的酶学性质和特异性抑制剂筛选奠定了基础。 相似文献
12.
以3个日龄的5个品系F、D、Y、S、B优质肉鸡为试验对象,采用组织化学切片染色技术进行组织学观察,探讨优质鸡肌纤维的发育规律及其对肉品质的影响.结果表明,随着日龄的增加鸡肌纤维的发育呈明显变化.70-90日龄的肌纤维面积的生长强度小于90-120日龄,而肌纤维密度70-90日龄的生长强度大于90-120日龄.同一生长阶段不同品系间肌纤维的生长强度也明显不同,生长较快的D系肌纤维生长强度最大.相关分析表明,肌纤维面积与肌纤维密度呈极显著负相关(P<0.01),与硫胺素含量呈显著正相关(P<0.05),与嫩度、肉色、肌内脂肪含量、肌苷酸含量呈正相关,但相关性不显著(P>0.05).可见,肌纤维的生长发育对肌肉的干物质、肌内脂肪等肉质性状及硫胺素、肌苷酸等风味物质的产生有利. 相似文献
13.
对闭鞘姜的基本营养成分作了较为全面的分析测定。结果表明：粗蛋白含量为4．43％,氨基酸种类齐全,并含有VB1,VB2,VC,VE及胡萝卜素等多种维生素,矿质元素含量丰富,还含有适量的纤维素、可溶性糖、酸及果胶等营养成分;重金属含量,化肥、农药残留量均未超过国家标准。因此,闭鞘姜营养成分种类齐全,含量丰富,具有较高的营养价值。 相似文献
14.
The percentage of isolated bean roots nodulated and the number of nodules per root were increased by the addition of mesoinositol to the agar medium into which the bases of bean roots were inserted. The following were without marked effect: glycine, thiamine, pyrodoxine, niacin, indoleacetic acid, gibberellic acid, kinetin, adenine, adenosinetriphosphate, biotin, riboflavin, calcium pantothenate, and folic acid. 相似文献
15.
采用化学分析方法,分析月季花花瓣和花蕊中常规营养成分,为月季的可食用性研究提供基础。结果表明:每100 g月季花瓣中营养成分含量为:水分85.36 g,灰分0.53 g,蛋白质0.92 g,脂肪0.87 g,总糖5.50 g;硫胺素0.35mg,核黄素0.70 mg;钙26.37 mg,铁0.0063 mg。月季花瓣中必需氨基酸种类齐全,营养价值较高,作为食用花卉具有较大的开发潜力。 相似文献
16.
保加利亚乳杆菌和嗜热链球菌联合发酵的番茄汁和胡萝卜汁随发酵时间延长，ｐＨ值降低，菌数增加。番茄汁和胡萝卜汁经发酵后核黄素、硫胺素、吡哆醇的含量增加而抗坏血酸的数量却减少了。发酵番茄汁和胡萝卜汁中谷氨酸含量较高，而一些含硫氨基酸的数量较少。本实验确定了适宜的发酵温度和接种量，并给出了蔬菜汁活性乳酸菌饮料的生产工艺流程，证明调制后的活性乳酸菌饮料具有良好的工艺学性状。 相似文献
17.
[目的]分析犏牛屠宰性能和风味物质.[方法]以青海犏牛为材料,利用高效液相色谱等方法,对青海犏牛性能指标测定和风味物质进行测定,并通过相关文献对比分析青海犏牛与牦牛的屠宰性能及风味物质.[结果]青海犏牛体尺性状和屠宰性状优于牦牛,且风味物质谷氨酸钠、肌苷、肌苷酸和硫胺素均高于牦牛,其风味更加优质鲜美.[结论]青海犏牛杂种优势明显. 相似文献
18.
小麦籽粒含有多种B族维生素,本研究通过测定24个不同粒色的小麦品种中维生素B1、维生素B2、维生素B6及籽粒色素含量,并研究不同颜色的小麦籽粒中B族维生素含量与小麦籽粒颜色的关系及其变异规律,为B族维生素的利用及小麦品质育种提供依据。应用超高效液相色谱-串联质谱法,采用大气压电喷雾离子源,正离子模式,多反应检测（MRM）模式精确测定小麦籽粒中维生素B1、维生素B2、维生素B6,分光光度法测定小麦籽粒色素含量。黑小麦76和VICTO杂交后代F8代12个姊妹系B族维生素含量变化很大,12个姊妹系间维生素B1、维生素B2、维生素B6的含量差异达极显著水平。冬鉴系列的10个小麦品种（系）维生素B1、维生素B2、维生素B6的含量差异达显著水平。相关分析表明,籽粒色素含量与B族维生素含量不存在显著正相关,籽粒颜色深小麦并不一定富含B族维生素。小麦籽粒中B族维生素含量受基因型的影响, 可以通过遗传改良的手段提高B族维生素在小麦籽粒中的含量。黑小麦76（母本）和VICTO（父本）杂交产生的F8代12个姊妹系的小麦籽粒中B族维生素含量存在着明显的超高亲杂种优势,因此,可通过有性杂交,培育高B族维生素含量的小麦品种。 相似文献
19.
本文提出了利用反相离子对色谱法,简单,快速,准确同时定量测定饲料添加剂中的烟酸,烟酰胺,盐酸吡哆辛,氰钴胺素,核黄素和硫胺素。样品前处理简单,六个维生素能在12min内获得满意的分离,各组份之间的分离度Rs大于1.60。各个维生素的回收率在87.0～101.0％,相对偏差为3.1～2.0％。色谱柱为LichrosorbRP-18 250×φ5mm,流动相为甲醇/水,0.25％TEA,1.25mmol/l PICB-5,3.75mmol/l PICB-7,pH3.00,紫外可变波长检测器采用MAXPL操作方式λ 1=254nm,λ_2=280nm,λ_3=354nm,流速1.1 nl/min。 相似文献
20.
Riboswitches are untranslated regions of messenger RNA, which adopt alternate structures depending on the binding of specific metabolites. Such conformational switching regulates the expression of proteins involved in the biosynthesis of riboswitch substrates. Here, we present the 2.9 angstrom-resolution crystal structure of the eukaryotic Arabidopsis thaliana thiamine pyrophosphate (TPP)-specific riboswitch in complex with its natural ligand. The riboswitch specifically recognizes the TPP via conserved residues located within two highly distorted parallel "sensor" helices. The structure provides the basis for understanding the reorganization of the riboswitch fold upon TPP binding and explains the mechanism of resistance to the antibiotic pyrithiamine. 相似文献