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971.
This article presents for the first time a modified protocol for RNase protection analysis that allows the substitution of32P with33P without loss of the high sensitivity of this method achieved with32P. With this protocol, we were able to detect at least 1 pg of specific mRNA. In the RNase protection analysis33P labeled riboprobes are more advantageous with regard to an easier handling and better resolution. 相似文献
972.
Vittorio Moretto Fernando Formaggio Marco Crisma Gian Maria Bonora Claudio Toniolo Ettore Benedetti Antonello Santini Michele Saviano Benedetto Di Blasio Carlo Pedone 《Journal of peptide science》1996,2(1):14-27
A complete series of terminally blocked, monodispersed homo-oligopeptides (to the pentamer level) from the sterically demanding, medium-ring alicyclic Cα,α-disubstituted glycine 1-aminocyclooctane-1-carb oxylic acid (Ac8c), and two Ala/Ac8c tripeptides, were synthesized by solution methods and fully characterized. The preferred conformation of all the oligopeptides was determined in deuterochloroform solution by IR absorption and 1H-NMR. The molecular structures of the amino acid derivative Z-Ac8c-OH, the dipeptide pBrBz- (Ac8c)2-OH and the tripeptide pBrBz-(Ac8c)3-OtBu were assessed in the crystal state by X-ray diffraction. Conformational energy computations were performed on the monopeptide Ac-Ac8c-NHMe. Taken together, the results obtained strongly support the view that the Ac8c residue is an effective β-turn and helix former. A comparison is also made with the conformational preferences of α-aminoisobutyric acid, the prototype of Cα, α-disubstituted glycines, and of the other members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n=3, 5–7) investigated so far. The implications for the use of the Ac8c residue in peptide conformational design are considered. 相似文献
973.
神经节苷脂GM_3对小鼠腹腔常驻巨噬细胞(R-M)和Ge-132体内激活的巨噬细胞(Ge-132-M)的磷脂代谢转换有显著的影响,当这两种M在体外用GM_3处理时,表现出[ ̄(32)P]Pi和[ ̄3H]肌醇参入PI降低,参入PIP、PIP_2增加;但在[ ̄(32)P]Pi和[ ̄3H]胆碱参入PC上,R-M与Ge-132-M不同,即GM_3促进同位素前体参入R-M的PC,抑制它们参入Ge-132-M的PC.以上结果表明GM3可能提高了PI或PIP的磷酸激酶的活性,致使[ ̄(32)P]PIP和[ ̄(32)P]PIP_2增多,[ ̄(32)P]PI减少.激活的M(Ge-132-M)本身PC代谢转换率较R-M高,当Ge-132-M再受GM_3刺激,PC代谢转换率降低,这提示GM_3对激活的M的PC代谢转换有调节作用. 相似文献
974.
从人良性增生前列腺组织中经硫酸铵沉淀和肝素-琼脂糖凝胶层析纯化出人前列腺生长因子(hPGF),纯化倍数约1000倍,SDS-PAGE和等电聚焦电泳示分子量约为17kD、等电点同标准bFGF,利用分离培养的人前列腺间质成纤维细胞进行活性鉴定,发现以1.3~1.7mol/LNaCl洗脱部分为hPGF,活性最高,对间质成纤维细胞有显著刺激增殖作用。 相似文献
975.
在吲哚乙酸不同位点偶联载体蛋白对其抗体特异性的影响 总被引:2,自引:0,他引:2
分别选择吲哚乙醇分子上的C1位羧基和吲哚环上的N位作为偶联载体蛋白的位点,用混合酸酐法和甲醛搭桥法分别合成了两种免疫原IAA—CO—NH一HSA和IAA-N-BSA,并进而制得了对吲哚乙酸侧链识别能力不同的两种多克隆抗体,分别可特异识别甲酯化IAA和游离态IAA;用碳化二亚胺法和甲醛搭桥法分别合成IAA—CO—NH-BSAbIAA—N—OVA两种复合物,以之为包被物,建立了两种IAAELISA。其灵敏度分别为0.35pmol和1.80ppmol;检测范围分别为0.78~800pmol和1.95~2000pmol;批内变异系数分别为4.45%和4.79%;批间变异系数分别为1.15%和1.50%。笔者用这两种ELISA检测了兰花气生根和桑树苗样品中IAA的含量,发现两种检测结果相当一致。 相似文献
976.
Forskolin(FSK)是一种植物二萜类化合物,为腺苷酸环化酶的特异激活剂,实验发现:FSK和作为参照的诱导分化剂维甲酸(RA)单独或联合应用均可升高胞浆蛋白激酶C(PKC)活性,并降低膜PKC活性,FSK可使表皮生长因子(EGF)诱导的细胞内三磷酸肌醇(IP3-1,4,5)水平降低至对照组的44.4%至67%;FSK与RA合用可显著降低成骨样细胞特征蛋白碱性磷酸酶(AKP)的活性。以上结果表明,FSK对成骨样细胞内磷脂酰肌醇信息传递体系有深刻影响,可能与其调节细胞的增殖分化有关。 相似文献
977.
To obtain general rules of peptide design using α,β-dehydro-residues, a sequence with two consecutive ΔPhe-residues, Boc-L -Val-ΔPhe–ΔPhe- L -Ala-OCH3, was synthesized by azlactone method in solution phase. The peptide was crystallized from its solution in an acetone/water mixture (70:30) in space group P61 with a=b=14.912(3) Å, c= 25.548(5) Å, V=4912.0(6) Å3. The structure was determined by direct methods and refined by a full matrix least-squares procedure to an R value of 0.079 for 2891 observed [I?3σ(I)] reflections. The backbone torsion angles ?1=?54(1)°, ψ1= 129(1)°, ω1=?177(1)°, ?2 =57(1)°, ψ2=15(1)°, ω2 =?170(1)°, ?3=80(1)°, ψ3 =7(2)°, ω3=?177(1)°, ?4 =?108(1)° and ψT4=?34 (1)° suggest that the peptide adopts a folded conformation with two overlapping β-turns of types II and III′. These turns are stabilized by two intramolecular hydrogen bonds between the CO of the Boc group and the NH of ΔPhe3 and the CO of Val1 and the NH of Ala4. The torsion angles of ΔPhe2 and ΔPhe3 side chains are similar and indicate that the two ΔPhe residues are essentially planar. The folded molecules form head-to- tail intermolecular hydrogen bonds giving rise to continuous helical columns which run parallel to the c-axis. This structure established the formation of two β-turns of types II and III′ respectively for sequences containing two consecutive ΔPhe residues at (i+2) and (i+3) positions with a branched β-carbon residue at one end of the tetrapeptide. 相似文献
978.
A.T. Grazul-Bilska L.P. Reynolds J.D. Kirsch J.J. Bilski D.A. Redme 《Prostaglandins & other lipid mediators》1996,52(4):285-302
Cellular interactions mediated by both contact-dependent and contact-independent mechanisms are probably important to maintain luteal function. The present studies were performed to evaluate the effects of luteotropic and luteolytic hormones, and also intracellular regulators, on contact-dependent gap junctional intercellular communication (GJIC) of bovine luteal cells from several stages of luteal development. Bovine corpora lutea (CL) from the early, mid and late luteal phases of the estrous cycle were dispersed with collagenase and incubated with no treatment, LH, PGF or LH + PGF (Experiment 1), or with no treatment, or agonists or antagonists of protein kinase C (TPA or H-7) or calcium (A23187 or EGTA; Experiment 2). After incubation, media were collected for determination of progesterone concentrations. Then the rate of GJIC was evaluated for small luteal cells in contact with small luteal cells, and large luteal cells in contact with small luteal cells by using the fluorescence recovery after photobleaching technique and laser cytometry. Luteal cells from each stage of the estrous cycle exhibited GJIC, but the rate of GJIC was least (P<0.05) for luteal cells from the late luteal phase. LH increased (P<0.05) GJIC between small luteal cells from the mid and late but not the early luteal phase. PGF increased (P<0.05) GjIC between small luteal cells from the mid luteal phase and diminished (P<0.05) LH-stimulatory effects on GjIC between small luteal cells from the late luteal phase. Throughout the estrous cycle, TPA decreased (P<0.05) the rate of GjIC between large and small, and between small luteal cells, and A23187 decreased (P<0.05) the rate of GJIC between large and small luteal cells. LH and LH + PGF, but not PGF alone increased (P<0.05) progesterone secretion by luteal cells from the mid and late luteal phases. Agonists or antagonists of PKC or calcium did not affect progesterone secretion by luteal cells. These data demonstrate that both luteal cell types communicate with small luteal cells, and the rate of communication depends on the stage of luteal development. LH and PGF affect GjIC between small luteal cells during the fully differentiated (mid-luteal) and regressing (late luteal) stages of the estrous cycle. In contrast, at all stages of luteal development, activation of PKC decreases GjIC between small and between large and small luteal cells, whereas calcium ionophore decreases GjIC only between large and small luteal cells. Luteotropic and luteolytic hormones, and intracellular regulators, may be involved in regulation of cellular interactions within bovine CL which likely is an important mechanism for coordination of luteal function. 相似文献
979.
Net O2 evolution, gross CO2 uptake and net HCO
inf3
su–
uptake during steady-state photosynthesis were investigated by a recently developed mass-spectrometric technique for disequilibrium flux analysis with cells of the marine cyanobacterium Synechococcus PCC7002 grown at different CO2 concentrations. Regardless of the CO2 concentration during growth, all cells had the capacity to transport both CO2 and HCO
inf3
su–
; however, the activity of HCO
inf3
su–
transport was more than twofold higher than CO2 transport even in cyanobacteria grown at high concentration of inorganic carbon (Ci = CO2 + HCO
inf3
su–
). In low-Ci cells, the affinities of CO2 and HCO
inf3
su–
transport for their substrates were about 5 (CO2 uptake) and 10 (HCO
inf3
su–
uptake) times higher than in high-Ci cells, while air-grown cells formed an intermediate state. For the same cells, the intracellular accumulated Ci pool reached 18, 32 and 55 mM in high-Ci, air-grown and low-Ci cells, respectively, when measured at 1 mM external Ci. Photosynthetic O2 evolution, maximal CO2 and HCO
inf3
su–
transport activities, and consequently their relative contribution to photosynthesis, were largely unaffected by the CO2 provided during growth. When the cells were adapted to freshwater medium, results similar to those for artificial seawater were obtained for all CO2 concentrations. Transport studies with high-Ci cells revealed that CO2 and HCO
inf3
su–
uptake were equally inhibited when CO2 fixation was reduced by the addition of glycolaldehyde. In contrast, in low-Ci cells steady-state CO2 transport was preferably reduced by the same inhibitor. The inhibitor of carbonic anhydrase ethoxyzolamide inhibited both CO2 and HCO
inf3
su–
uptake as well as O2 evolution in both cell types. In high-Ci cells, the degree of inhibition was similar for HCO
inf3
su–
transport and O2 evolution with 50% inhibition occurring at around 1 mM ethoxyzolamide. However, the uptake of CO2 was much more sensitive to the inhibitor than HCO
inf3
su–
transport, with an apparent I50 value of around 250 M ethoxyzolamide for CO2 uptake. The implications of our results are discussed with respect to Ci utilisation in the marine Synechococcus strain.Abbreviations Chl
chlorophyll
- Ci
inorganic carbon (CO2 + HCO
inf3
su–
)
- CA
carbonic anhydrase
- CCM
CO2-concentrating mechanism
- EZA
ethoxyzolamide
- GA
glycolaldehyde
- K1/2
concentration required for half-maximal response
- Rubisco
ribulose-1,5,-bisphosphate carboxylase-oxygenase
D.S. is a recipient of a research fellowship from the Deutsche Forschungsgemeinschaft (D.F.G.). In addition, we are grateful to Donald A. Bryant, Department of Molecular and Cell Biology and Center of Biomolecular Structure Function, Pennsylvania State University, USA, for sending us the wild-type strain of Synechococcus PCC7002. 相似文献
980.
Summary Genetic studies have demonstrated biparental inheritance of plastids in alfalfa. The ratio of paternal to maternal plastids in the progeny varies according to the genotypes of the parents, which can be classified as strong or weak transmitters of plastids. Previous cytological investigations of generative cells and male gametes have provided no consistent explanation for plastid inheritance patterns among genotypes. However, plastids in the mature egg cells of a strong female genotype (6–4) were found to be more numerous and larger than in mature eggs of a weak female genotype (CUF-B), and the plastids in 6–4 eggs are positioned equally around the nucleus. In CUF-B, the majority of plastids are positioned below (toward the micropyle) the mid level of the nucleus, which is the future division plane of the zygote. Since only the apical portion of the zygote produces the embryo proper, plastids in the basal portion were predicted to become included in the suspensor cells and not be inherited. In the present study, we examined zygotes and a two-celled proembryo from a cross between CUF-B and a strong male genotype (301), a cross that results in over 90% of the progeny possessing paternal plastids only. Our results indicate that the distribution of plastids observed in the CUF-B egg cell is maintained through the first division of the zygote. Further, paternal plastids are similarly distributed; however, within the apical portion of the zygote and in the apical cell of the two-celled proembryo, the number of paternal plastids is typically much greater than the number of maternal plastids. These findings suggest that maternal and paternal plastid distribution within the zygote is a significant factor determining the inheritance of maternal and paternal plastids in alfalfa. 相似文献