猪心原肌球蛋白的自旋标记研究

从猪心肌中提取的原肌球蛋白(TM),用2,2,6,6-四甲基-4-(二氯三氮嗪代)氨基哌啶-1-氧基进行自旋标记。产物(SL-TM)的ESR波谱属弱固定型。观察了三种变性手段(热、盐酸胍、脲)对上述波谱的影响。SL-TM经酶解后所得ESR波谱与标记物稀溶液的波谱相似,由此测定SL-TM中标记物的结合量。对SL-TM进行变温测定所得Arrhenius图显示两个转折点(TM的构象转变温度),约为45℃和74—75℃,后一种温度迄今未见文献报道。而SL-TM的酶降解产物在对微波功率饱和与变温的响应中的行为则与之截然不同。     

辐射引起的自旋从脱氧核糖核酸(DNA)及胸苷酸(TMP)向没食子酸丙酯转移

本文用小牛胸腺DNA、没食子酸丙酯(PG)和它们的5种分子混合物(PG含量为1—20％)在真空及296°K用γ射线辐照。根据ESR谱形及自由基微波饱和特性,可推断辐射引起的自旋能从DNA向PG转移。PG的自旋产率比其单独辐照时高出2—3个数量级。在自旋转移比率与之间发现有良好的线性关系(r为核苷酸对PG的克分子比率)。在77°K测定说明,此种自旋转移是由于氢转移机制。作者还证实从γ射线辐照的热变性DNA或TMP向PG的自旋转移,并讨论了有关机制。     

乌骨鸡黑素的元素组成与自由基状态初探

乌骨鸡(Gallina lanigera),又名白绒毛鸡,为我国特产的药用鸡种.远在唐代即知乌骨鸡能治风湿等病,明代李时珍在《本草纲目》中亦记载其药效.乌骨鸡的皮肤、肌肉、骨膜及内脏(除心、肝及肺外)中含有大量黑素,但其化学性质迄未鉴定.我们推测可利用黑素的自由基状态来探索黑素的理化性质及其与结构和功能的关系.Commoner 等于1954年最先发现在含黑素的组织(蛙卵)中自由基含量很     

四种哌啶系氮氧自由基的ESR特性研究——固态特性、溶液中的浓度效应和溶剂效应

本文研究四种哌啶系氮氧自由基在固态与在溶液中的ESR特性.它们在固态均显示单峰波谱,而在浓度小于1×10~(-2)M的溶液中则显示三峰波谱.观察并比较溶液中的自由基浓度、溶剂的极性和粘度对ESR波谱五种参数的影响。在超精细分裂常数 A_N与溶剂极性参数 Kosower Z值之间得出线性关系.实验数据表明,自由基的旋转相关时间τ亦与溶剂粘度η成线性关系.并发现高场峰的相对高度与η成反比.对氮氧自由基的这些ESR特性作了讨论。     

ESR STUDIES OF SPIN-TRAPPED RADICALS IN GAMMA-IRRADIATED POLYCRYSTALLINE PYRIMIDINE NUCLEOSIDES——THYMIDINE AND DEOXYCYTIDINE HYDROCHLORIDE

Room-temperature free radicals produced in gamma-irradiated polyerystalline thymidine and deoxy-cytidine hydrochloride were studied by spin-trapping and ESR methods with NtB (nitroso-t-butane) serv-ing as the spin trap. Three types and two types of base radicals were identified for them respectively,which was completely consistent with the results in single-crystal ESR studies, and thereby standard ESRspectra of their R·spin adducts were obtained. In addition, ribose radicals HOC(5')HC(4')H 相似文献   

ESR STUDIES OF SPIN-TRAPPED RADICALS IN GAMMA-IRRADIATED POLYCRYSTALLINE PYRIMIDINE NUCLEOSIDES——CYTIDINE, DEOXYCYTIDINE, URIDINE AND DEOXYURIDINE

Room-temperature free radicals produced in four gamma-irradiated polycrystalline pyrimidine nucleosides (cytidine, deoxycytidine, uridine and deoxyuridine) were studied by an improved spin trapping and ESR methods with NtB (nitroso-t-butane) serving as the spin trap. The presence of three types of radicals was ascertained in all samples, i.e. —C(5)H—C(6) H_2—and —C(5)H_2—C(6)H— base radicals, and —C(5')H_2— ribose radical evolving from HOC(5')H—C(4')H<. In addition, radicals in which the unpaired electron was located on ribose C(1') and C(4') sites were tentatively distinguished. Stress was laid on the discussion of the mechanism of formation of ribose radicals.     

γ射线辐照的多晶态嘧啶核苷类中自旋捕捉自由基的ESR研究——Ⅱ.胸苷和脱氧胞苷盐酸盐

本文以NtB(亚硝基特丁烷)为捕捉剂,利用自旋捕捉(Spin Trapping)和ESR方法,研究了γ射线辐照的多晶态胸苷和脱氧胞苷盐酸盐中产生的室温自由基。对它们分别确定了三种类型与两种类型的碱基自由基,此与单晶ESR研究结果完全一致,从而获得它们R·自旋加合物的标准ESR波谱。此外,对脱氧胞苷盐酸盐还确定了在单晶ESR研究中未被鉴别的核糖自由基HO(5′)HC(4′)H<及由其演变而成的—(5′)H_2自由基。     

STUDIES ON THE ESR CHARACTERISTICS OF FOUR PIPERIDINE NITROXYL RADICALS——CHARACTERISTICS IN THE SOLID STATE,CONCENTRATION EFFECTS AND SOLVENT EFFECTS IN SOLUTIONS

The ESR characteristics are studied for four piperidine nitroxyl radicals in the solidstate and in solutions. They all exhibited singlet ESR spectra in the solid state, but tripletspectra in solutions at a concentration lower than 1×10~(-2)M. The effects of the free radi-eal coneentration and the polarity trod the viscosity of solvents were observed and comparedon five ESR spectral parameters. Linear correlations could be found between the hyperfinesplitting constant A_N and the solvent polarity parameter, namely, Kosower Z value, Ex-perimental data showed also linear relations of the rotational correlation time τ of free rad-icals with the solvent viscosity, η. We have further found that the relative height of thehigh-field peak varied inversely with η. These ESR characteristics of nitroxyl radicals arediscussed.     

γ射线辐照的多晶态嘧啶核苷类中自旋捕捉自由基的ESR研究——Ⅰ.胞苷、脱氧胞苷、尿苷和脱氧尿苷

本文以NtB(亚硝基特丁烷)为捕捉剂,利用自旋捕捉(Spin Trapping)和ESR方法,研究了γ射线辐照的四种多晶态嘧啶核苷(胞苷、脱氧胞苷、尿苷和脱氧尿苷)中产生的室温自由基。对所有样品确定了有三种类型的自由基存在,即—(?)(5)H-C(6)H_2-和-C(5)H_2-(?)(6)H-碱基自由基以及由HO(?)(5′)H-C(4′)H<演变而来的—(?)(5′)H_2核糖自由基。此外,还倾向于鉴别出未成对电子定域在核糖C(1′)和C(4′)位的自由基。着重讨论了核糖自由基形成的机制。     

TRANSFER OF RADIATION-INDUCED SPINS FROM DEOXYRIBONUCLEIC AND TH

When calf thymus deoxyribonucleic acid (DNA), propyl gallate (PG) and their five mo-ecular mixtures (with PG content of 1, 2, 5, 10 and 20%) are irradiated with γ-rays indry state in vacuum at 296°K, the ESR spectra of all molecular mixtures differ strikinglyfrom those of DNA, but bear a close resemblance to those of PG. The spin yield in the PGcontained in these mixtures is two to three orders of magnitude higher than that in the caseof PG irradiated separately. Furthermore, on the basis of the relative saturation characteris-tics of ESR spectra, these molecular mixtures behave more like PG than like DNA. It maybe inferred that the radiation-induced spins could be transferred from DNA to PG. Withr representing the molar ratio of nucleotides to PG, we have found a good linear correlationbetween the transfer ratio (TR) and r~(1/2). One PG molecule could protect at least 68 nu-eleotides in the duplex DNA chain, and thereby the minimal range of spin transfer is estimat-ed at 115 ?. Results obtained from irradiation at 77°K show that PG exerts no protectiveeffect on DNA, so DNA sustains an irreversible damage. It is thought that the spin transferfrom DNA to PG is exclusively due to a hydrogen transfer mechanism. We have also demons-trated the transfer of radiation-induced spins from both thermally denatured DNA and TMPto PG. The former process can be ascribed primarily to the hydrogen transfer mechanism,Whereas the latter, as in the case of native DNA, exclusively to this mechanism.