Studies on the structure of NADH: ubiquinone oxidoreductase complex: topography of the subunits of the iron-sulfur protein component

Resolution of the mitochondrial NADH:ubiquinone oxidoreductase complex (Complex I) by chaotropic agents result in the separation of three building blocks of the enzyme, designated FP (flavoprotein), IP (iron-sulfur protein), and HP (hydrophobic protein). FP contains three subunits of Mr 51, 24, and 9 kDa; one FMN; and two iron-sulfur clusters. Immunochemical studies with monospecific antibodies to the FP subunits have indicated that all three subunits of FP protrude from the inner mitochondrial membrane on the matrix side, whereas no reactive epitopes from these subunits were found exposed on the cytosolic side [A.-L. Han, T. Yagi, and Y. Hatefi (1988) Arch. Biochem. Biophys. 267, 490-496]. IP contains six subunits of Mr 75, 49, 30, 18, 15, and 13 kDa and four iron-sulfur clusters. In the present study, immunochemical experiments (enzyme-linked immunosorbent assays and 125I-protein A labeling) were carried out with monospecific antibodies to the above IP subunits and with bovine Complex I, submitochondrial particles, mitoplasts, and intact mitochondria as sources of antigens. Results have indicated that all six IP subunits protrude from the inner mitochondrial membrane into the matrix, and that the 75-kDa subunit, and possibly the 15-kDa subunit, protrude in mitoplasts from the cytosolic side as well. No epitopes reactive toward the monospecific antibodies to the 49-, 30-, 18-, and 13-kDa subunits were detected in mitoplasts.     

Resonance Raman studies of Escherichia coli sulfite reductase hemoprotein. 2. Fe4S4 cluster vibrational modes

Resonance Raman (RR) spectra from the hemoprotein subunit of Escherichia coli sulfite reductase (SiR-HP) are examined in the low-frequency (200-500 cm-1) region where Fe-S stretching modes are expected. In spectra obtained with excitation in the siroheme Soret or Q bands, this region is dominated by siroheme modes. Modes assignable to the Fe4S4 cluster are selectively enhanced, however, with excitation at 488.0 or 457.9 nm. The assignments are confirmed by observation of the expected frequency shifts in SiR-HP extracted from E. coli grown on 34S-labeled sulfate. The mode frequencies and isotopic shifts resemble those seen in RR spectra of other Fe4S4 proteins and analogues, but the breathing mode of the cluster at 342 cm-1 is higher than that observed in the other species. Spectra of various ligand complexes of SiR-HP reveal only slight sensitivity of the cluster terminal ligand modes to the presence of exogenous heme ligands, at variance with a model of ligand binding in a bridged mode between heme and cluster. Close examination of RR spectra obtained with siroheme Soret-band excitation reveals additional 34S-sensitive features at 352 and 393 cm-1. These may be attributed to a bridging thiolate ligand.     

The specific binding activities of human urinary radioiodinated colony-stimulating factor-1 to various human tissue cells

1. Colony-stimulating factor (CSF-1) was isolated from a large volume of fresh normal human urine by 5 steps of purification and enrichment. 2. The purification factor is 100,000 fold and the purified compound exhibits a 2.16 x 10(7) U/mg of protein sp. act. 3. The isolated CSF-1 is a sialoglycoprotein with 41.5% of carbohydrate. The almost complete removal of this carbohydrate moiety (up to 91%) was achieved by incubation with trifluoromethane sulfonic acid. 4. The deglycosylated CSF-1 (DG-CSF-1) possesses an apparent Mr 38,000 compared to native CSF-1 with an initial Mr 57,000 (Goa et al., 1988). 5. The features of the interaction of radio-iodinated [125I]CSF-1 with single cell suspensions from various human tissues (bone marrow, spleen, blood, peritoneal cavity, alveolar lavage, lymph node and thymus), were studied. 6. The binding activity of peritoneal macrophages was the highest among the cells examined and erythrocytes, thymus and blood granulocytes showed no CSF-1 binding. 7. On incubation with [125I]CSF-1 at 0 degrees C, cellular binding of [125I]CSF-1 reached a stable maximum within 16 hr. This is in contrast to the association behaviour at higher temperature. 8. At 37 degrees C, cellular associated [125I]CSF-1 levels reached, within 90 min, an unstable maximum which was up to 10 times less than that occurring under the same conditions at 0 degree C. From the Scatchard plot analysis, we obtained the affinity constant and the number of receptor(s). 9. The binding site is sensitive to trypsin. 10. The receptor alone, (labelled by cross-linking to [125I]CSF-1 with di-succinylimidyl-suberate), is a polypeptide with an approx. Mr 110,000. 11. Our results showed that the receptor of CSF-1 is a tyrosin-kinase.     

Relation of phosphatidylinositol metabolism to glycolytic pathway in skeletal muscle membranes

Skeletal muscle triads are possessing the whole set of enzymes of the phosphatidylinositol (PI)-linked signal generating pathway, PI-kinase, PI(4)P-kinase, and PI(4,5)P₂-phospholipase C (PLC). The activities of these enzymes are comparable to those found in other cell types for which a functional role of the PI-pathway in intracellular signal transduction has been established. For skeletal muscle an unequivocal function and an initiating signal for Ins(1,4,5)P₃-liberation is still unknown. However, the observed Ca-dependency of PLC activity suggests that here Ins(1,4,5)P₃ production is a consequence rather than a cause of increasing cytosolic Ca²⁺. Recently, the glycolytic enzyme aldolase, whose activity can be modulated by inositol polyphosphates, has been localized in the triadic structure. The enzyme which has a high affinity to Ins(1,4)P₂, Ins(1,4,5)P₃ and Ins(1,3,4,5)P₄, seems to be compartmentalized to the junctional foot structure from which it is released upon binding of these molecules. This phenomenon could reflect a capability for regulation of the glycolytic flux even for aldolase, especially if a non steady-state situation in the junctional gap is considered. Meanwhile we have accumulated evidence for the operation of a partial glycolytic sequence in the junctional region established by the enzymes aldolase, glyceraldehyde-3-P (GAP) dehydrogenase and phosphoglycerate kinase. This system is able to produce ATP upon oxidation of GAP and could be, because of the inositol polyphosphate-sensing abilities of aldolase, a target for the membrane associated PI-pathway. The ATP production is however transient which indicates the coupling to an ATP hydrolyzing reaction. Thus, it appears that the ATP produced by the membrane associated system is effectively utilized by an ATP consuming membrane localized system like PI-metabolism or protein kinases. There are indications that exogeneously added ATP does not equilibrate with the ATP synthesized in the junctional region which suggests an effective structural or kinetical compartmentalization of this system. Therefore it is hypothesized that the ATP synthesized by the membrane associated glycolytic sequence is utilized in membrane localized reactions.     

红豆草根瘤侵染细胞的超微结构变化

红豆草(Onobrychis viciaefolia Scop.)是一种抗旱、耐寒、耐热和耐瘠薄的优良豆科牧草,不仅是很好的饲料和绿肥,而且还能大量结瘤固氮,提高土地肥力。因此,它在我国甘肃和其他北方干旱和半干旱贫瘠地区广为种植。虽然不少学者曾对它的引种条件、生产性能、营养成分和形态解剖作过许多研究,但对其共生固氮,特别是与共生固氮息息相关的根瘤在发育中的变化却至今尚无系统报道。因此,为了更好开发利用这一资源,     

椭圆斜羽叶的解剖研究及斜羽叶的系统分类位置

本文根据对椭圆斜羽叶(Plagiozamites oblongifolius)钙质石化化石的研究,认为其主要特征如下:羽状复叶,叶肉无海绵组织和栅栏组织分化。羽片叶脉维管束外韧式,木质部外始式,与现代苏铁属叶脉特征相近。羽轴维管束为“U”形,外始式木质部、梯状纹孔管胞,与现代苏铁属的羽轴维管束相似。根据上述特征,目前可将斜羽叶属归入原始苏铁类植物。但是,如果斜羽叶的生殖器官同 Noeggerathia 一样,为异孢型孢子囊穗,则斜羽叶可能为一种与苏铁类起源有关的原裸子植物。     

A reevaluation of the amino acid sequence of human follitropin beta-subunit

A collaborative study from two laboratories has been undertaken to re-evaluate the human follitropin -subunit sequence (hFSH), since areas of uncertainty remain in the wake of two earlier reports. The first report was by Shome and Parlow (1974). The second, by Saxena and Rathnam (1976), proposed revisions for sequence not definitively placed in the first study, as well as some differences in other placements. We have re-examined the sequence of the hFSH with more recent methodology. This has led to revision of certain areas of the sequence and resolution of differences between the two earlier proposals. Specifically, an-Ile-Ser- is established at 21–22, Asp at 41, Arg at 44, Lys at 46, and Glu at 111. These were areas of disagreement in the earlier proposals. A definitive placement of the residues around tryptophan-27 has now been obtained by three laboratories. C-terminal heterogeneity was observed with subunits ending at residue 107, 109, or 111. N-terminal heterogeneity has been observed in all preparations examined to date. A significant population of molecules with a proteolytic nick between residues 38–39 is noted. This is very likely an artifact of the collection and processing. The preparations examined in the present studies showed no evidence of residues 112–118 proposed by Saxena and Rathnam.     

白腹锦鸡鸣声的声谱分析

1986年1月—8月,12月及翌年1月,我们在云南省昆明市西部山区进行白腹锦鸡野外生态观察期间,录制了白腹锦鸡的鸣声。本文就啼叫声、呼唤声、惊叫声、恐惧叫声、威胁叫声及召唤雏鸟声等6种意义比较明确的鸣声进行了声谱分析,探讨各种鸣声与其相应的行为关系。     

豌豆根瘤侵染细胞衰老过程的电镜观察

用透射电镜观察了豌豆根瘤侵染细胞在衰老过程中的超微结构变化,结果表明,侵染细胞和拟菌体的衰老有一定的规律和特征,首先是一些包裹拟菌体的包囊变得疏松,包囊和拟菌体之间出现较大间隙,间隙中常有一些纤维状和泡状物质。然后,细胞质失去正常结构,逐渐凝聚为染色很深的团块,进而完全泡状化,伴随着拟菌体的衰老,寄主细胞质染色由深变浅,细胞器逐渐减少,最后,液泡和质膜相继破裂,细胞完全瓦解,有时在衰老细胞的胞间隙,或在衰老的细胞质中有一定年轻的细菌,甚至在一片崩溃的拟菌体中还有侵染丝,有的还正在向寄主细胞质释放细菌。     

Alzheimer's disease: study of the distribution of tau proteins constituting helical filament pairs in human central nervous tissue

Tau proteins are the major components of Paired Helical Filaments (PHF) of Alzheimer's disease. Using the immunoblot technique and an antiserum against PHF, we have studied the distribution of Tau proteins in the different areas of normal human brains and Alzheimer brains. Tau proteins were clearly present in cortical grey matter but were difficult to detect in the white matter. In Alzheimer brains, we observed two differences: first, there is an important background due to the partial dissociation of the lesions containing Tau aggregates. Second, the profile of Tau proteins is modified, due to abnormal phosphorylation. Thus, Tau proteins are found in large amounts in the grey matter of the cortical areas and are not exclusively distributed in the axonal domain. The normal cortical distribution of Tau in the human brain correlates well with the distribution of histological lesions that contain PHF (neurofibrillary tangles and neuritic plaques) in the Alzheimer cortex.