Inactivation of the cyclin-dependent kinase Cdc28 abrogates cell cycle arrest induced by DNA damage and disassembly of mitotic spindles in Saccharomyces cerevisiae

Eukaryotic cells may halt cell cycle progression following exposure to certain exogenous agents that damage cellular structures such as DNA or microtubules. This phenomenon has been attributed to functions of cellular control mechanisms termed checkpoints. Studies with the fission yeast Schizosaccharomyces pombe and mammalian cells have led to the conclusion that cell cycle arrest in response to inhibition of DNA replication or DNA damage is a result of down-regulation of the cyclin-dependent kinases (CDKs). Based on these studies, it has been proposed that inhibition of the CDK activity may constitute a general mechanism for checkpoint controls. Observations made with the budding yeast Saccharomyces cerevisiae, however, appear to disagree with this model. It has been shown that high levels of mitotic CDK activity are present in the budding yeast cells arrested in G2/mitosis as the result of DNA damage or replication inhibition. In this report, we show that a novel mutant allele of the CDC28 gene, encoding the budding yeast CDK, allowed cell cycle passage through mitosis and nuclear division in the presence of DNA damage and the microtubule toxin nocodazole at a restrictive temperature. Unlike the checkpoint-defective mutations in CDKs of fission yeast and mammalian cells, the cdc28 mutation that we identified was recessive and resulted in a loss of the CDK activity, including the Clb2-, Clb5-, and Clb6-associated, but not the Clb3-associated, CDK activities. Examination of several known alleles of cdc28 revealed that they were also, albeit partially, defective in cell cycle arrest in response to UV-generated DNA damage. These findings suggest that Cdc28 kinase in budding yeast may be required for cell cycle arrest resulting from DNA damage and disassembly of mitotic spindles.

The EH-domain-containing protein Pan1 is required for normal organization of the actin cytoskeleton in Saccharomyces cerevisiae

Normal cell growth and division in the yeast Saccharomyces cerevisiae involve dramatic and frequent changes in the organization of the actin cytoskeleton. Previous studies have suggested that the reorganization of the actin cytoskeleton in accordance with cell cycle progression is controlled, directly or indirectly, by the cyclin-dependent kinase Cdc28. Here we report that by isolating rapid-death mutants in the background of the Start-deficient cdc28-4 mutation, the essential yeast gene PAN1, previously thought to encode the yeast poly(A) nuclease, is identified as a new factor required for normal organization of the actin cytoskeleton. We show that at restrictive temperature, the pan1 mutant exhibited abnormal bud growth, failed to maintain a proper distribution of the actin cytoskeleton, was unable to reorganize actin the cytoskeleton during cell cycle, and was defective in cytokinesis. The mutant also displayed a random pattern of budding even at permissive temperature. Ectopic expression of PAN1 by the GAL promoter caused abnormal distribution of the actin cytoskeleton when a single-copy vector was used. Immunofluorescence staining revealed that the Pan1 protein colocalized with the cortical actin patches, suggesting that it may be a filamentous actin-binding protein. The Pan1 protein contains an EF-hand calcium-binding domain, a putative Src homology 3 (SH3)-binding domain, a region similar to the actin cytoskeleton assembly control protein Sla1, and two repeats of a newly identified protein motif known as the EH domain. These findings suggest that Pan1, recently recognized as not responsible for the poly(A) nuclease activity (A. B. Sachs and J. A. Deardorff, erratum, Cell 83:1059, 1995; R. Boeck, S. Tarun, Jr., M. Rieger, J. A. Deardorff, S. Muller-Auer, and A. B. Sachs, J. Biol. Chem. 271:432-438, 1996), plays an important role in the organization of the actin cytoskeleton in S. cerevisiae.

A status report on helium inductively coupled plasma mass spectrometry

The current status of helium inductively coupled plasma - mass spectrometry (He ICPMS) is examined, its potentials and limitations are reviewed, and a summary of fundamental properties of atmospheric pressure He ICP discharges is presented. Also included are results of He ICPMS studies with a new helium plasma torch (18 mm i.d.) operated at four sets of operating conditions. Under the "cold plasma" condition (600 W forward power), no secondary discharge is observed and ion kinetic energies ranging from 2.0 eV to 9.5 eV for 6 elements (mass range: 39-208) are measured. At higher power levels, the secondary discharge still is strong. In general, detection limits for certain elements are improved by 1-3 orders of magnitude compared to previous data acquired in 1993 with a 13-mm He ICP torch. Elements such as K, Fe, Cr, Mn, Ni, and Co that suffer from spectral interferences in Ar ICPMS can be detected at pg/mL-levels with an analogue detector and a prototype ICPMS instrument having no photon stops or obstacles present in the ion trajectory path.

[Preparation and identification of monoclonal antibody GB2 directed against human breast cancer serum antigen]

Spleen cells from BALB/c mice immunized with human breast cancer serum antigen were fused with murine myeloma SP 2/0 cells. After screening with ELISA and limited-dilution cloning, one hybridoma which could stably secrete specific antibody was obtained and designated McAbGB2. The titer of McAbGB2 was up to 1.2 x 10(6) after purified by ammonium sulfate and DEAE-cellulose. The McAbGB2 was defined as murine IgG1 by agarose double immunodiffusiong. Immunoblotting analysis revealed that the antigens with molecular weights of 116 kd and 45 kd recognized by McAbGB2 were distributed in human breast cancer tissue and serum.

Differential modulation of binding loop flexibility and stability by Arg50 and Arg52 in Cucurbita maxima trypsin inhibitor-V deduced by trypsin-catalyzed hydrolysis and NMR spectroscopy

The side chains of Arg50 and Arg52 iin Cucurbita maxima trypsin inhibitor-V (CMTI-V) anchor the binding loop to the scaffold region [Cai, M., Gong, Y., Kao, J.L-F., & Krishnamoorthi, R. (1995) Biochemistry 34, 5201-5211]. The consequences of these hydrogen-bonding and electrostatic interactions on the conformational flexibility and stability of the binding loop were evaluated by trypsin-catalyzed hydrolysis of CMTI-V mutants, in which each of the arginines was individually replaced with Ala, Lys, or Gln by genetic engineering methods. All mutants exhibited significantly increased vulnerability to the protease attack at many sites, including the reactive-site (Lys44-Asp45 peptide bond), with the R50 mutants showing much more pronounced effects than the R52 counterparts. For CmTI-V and the mutants studied, a qualitative correlation was inferred between binding loop flexibility and retention time on a reverse-phase high-pressure liquid chromatography C-18 column. The R50 mutants were found to be more flexible than the corresponding R52 versions. These results demonstrate that Arg50 contributes more to the stability and function of CMTI-V. The differing strengths of the hydrogen bonds made by Arg50 and Arg52 were characterized by determining the internal dynamics of their side chains at pH 5.0 and 2.5: 15N NMR longitudinal and transverse relaxation rates and 15N-1H nuclear Overhauser effect (NOE) enhancements were measured for the main-chain and side-chain NH groups in 15N-labeled recombinant CMTI-V (rCMTI-V) and the model-free parameters [Lipari, G., & Szabo, A.(1982) J. Am. Chem. Soc. 104, 4546-59; 4559-4570] were calculated. At both pH 5.0 and 2.5, the arginines at positions 26, 47, 58 and 66 are found to be highly mobile, as the caluculated general order parameters, S2 values, of their NepsilonH groups fall in the range 0.03-0.18. The corresponding values for Arg50 amd Arg52 are 0.73 and 0.63, respectively, at pH 5.0, thus confirming that the two arginines are rigid and hydrogen bonded. At pH 2.5, these hydrogen bonds are still retained with Arg50 appearing to be more restrained (S2 = 0.71) than Arg52 (S2 = 0.56). This is consistent a greater contribution by Arg50 to the conformational stability of the reactive-site loop in CMTI-V. The results also indicate that the Arg50 and Arg52 side chains are not hydrogen-bonded to carboxylate groups, which would be protonated at pH 2.5 and, hence, unavailable for hydrogen-bonding interactions. The overall folding of rCMTI-V appears not to be significantly affected by the pH change, as indicated by comparisons of 1H and 15N chemical shifts, sequential NOE cross-peaks, and S2 values of the backbone atoms, and the conserved side-chain dynamics of Trp9 and Trp54--residues that are involved in hydrophobic and hydrogen-bonding interactions with others in the protein core and the binding loop, respectively.

[Establishment of an effective way for separating and culturing tumor infiltrating lymphocytes]

The key to preparing TILs for clinical application is to enhance its capacity of proliferation and cytotoxicity. For this purpose we have made a study of methodology and established an effective way consisting of 3 processes to separate and culture TILs. It included: (1) mechanical splitting; (2) digesting with 0.05% collagenase I and 0.003% DNAase I mixture in room temperature for 6 hrs and 18hrs in cool, and (3) centrifuging with 75% and 100% Ficoll non-continuous grade density. The separated TILs were suspended in conditional culture medium for proliferation. Most of them reached the amount of 10(9) at the end of culture, which was essential for clinical therapy. Their NK and LAK activities were 56.3 +/- 11.7% and 48.6% +/- 10.6% respectively, in which the CD6+ T cells played an important role. The results suggest this a perfect way for separating and culturing TILs.

Solution structure and backbone dynamics of recombinant Cucurbita maxima trypsin inhibitor-V determined by NMR spectroscopy

The solution structure of recombinant Cucurbita maxima trypsin inhibitor-V (rCMTI-V), whose N-terminal is unacetylated and carries an extra glycine residue, was determined by means of two-dimensional (2D) homo and 3D hetero NMR experiments in combination with a distance geometry and simulated annealing algorithm. A total of 927 interproton distances and 123 torsion angle constraints were utilized to generate 18 structures. The root mean squared deviation (RMSD) of the mean structure is 0.53 A for main-chain atoms and 0.95 A for all the non-hydrogen atoms of residues 3-40 and 49-67. The average structure of rCMTI-V is found to be almost the same as that of the native protein [Cai, M., Gong, Y., Kao, J.-L., & Krishnamoorthi, R. (1995) Biochemistry 34, 5201-5211]. The backbone dynamics of uniformly 15N-labeled rCMTI-V were characterized by 2D 1H-15N NMR methods. 15N spin-lattice and spin-spin relaxation rate constants (R1 and R2, respectively) and [1H]-15N steady-state heteronuclear Overhauser effect enhancements were measured for the peptide NH units and, using the model-free formalism [Lipari, G., & Szabo, A. (1982) J. Am. Chem. Soc. 104, 4546-4559, 4559-4570], the following parameters were determined: overall tumbling correlation time for the protein molecule (tau m), generalized order parameters for the individual N-H vectors (S2), effective correlation times for their internal motions (tau e), and terms to account for motions on a slower time scale (second) due to chemical exchange and/or conformational averaging (R(ex)). Most of the backbone NH groups of rCMTI-V are found to be highly constrained ((S2) = 0.83) with the exception of those in the binding loop (residues 41-48, (S2) = 0.71) and the N-terminal region ((S2) = 0.73). Main-chain atoms in these regions show large RMSD values in the average NMR structure. Residues involved in turns also appear to have more mobility ((S2) = 0.80). Dynamical properties of rCMTI-V were compared with those of two other inhibitors of the potato I family--eglin c [Peng, J. W., & Wagner, G. (1992) Biochemistry 31, 8571-8586] and barley chymotrypsin inhibitor 2 [CI-2; Shaw, G. L., Davis, B., Keeler, J., & Fersht, A. R. (1995) Biochemistry 34, 2225-2233]. The Cys3-Cys48 linkage found only in rCMTI-V appears to somewhat reduce the N-terminal flexibility; likewise, the C-terminal of rCMTI-V, being part of a beta-sheet, appears to be more rigid.

Inhibition of nitric oxide formation with L-canavanine attenuates endotoxin-induced vascular hyporeactivity in the rat

L-Canavanine, a selective inhibitor of inducible nitric oxide (NO) synthase, has beneficial effects on the circulatory failure of rats with endotoxin shock. To investigate the direct relationship between these beneficial effects and the inhibition of the formation of NO in response to L-canavanine in endotoxin shock in the rat, we detected changes in venous nitrosyl-hemoglobin (NO-hemoglobin) levels using an electron spin resonance (ESR) assay. Anaesthetized rats were injected with lipopolysaccharide (10 mg/kg i.v.). 1 h after the lipopolysaccharide injection, the rats were divided into four groups: a lipopolysaccharide group receiving 0.3 ml of saline hourly, an L-canavanine 10 or an L-canavanine 20 group receiving L-canavanine 10 or 20 mg/kg i.v. hourly, respectively, and an L-NAME group receiving NG-nitro-L-arginine methyl ester (L-NAME) 15 mg/kg followed by 10 mg/kg i.v. hourly. A sham group received saline instead of lipopolysaccharide, and an L-canavanine group received L-canavanine 20 mg/kg i.v. hourly, 1 h after the saline injection. At 5 h after the lipopolysaccharide or saline injection, pressor responses to noradrenaline (1 microgram/kg i.v.) were obtained. In the lipopolysaccharide group, lipopolysaccharide caused a progressive decrease in mean arterial pressure and an impairment of pressor responsiveness to noradrenaline. Administration of L-canavanine or L-NAME attenuated the endotoxin-induced hypotension and vascular hyporeactivity to noradrenaline. L-Canavanine did not alter mean arterial pressure and the pressor response to noradrenaline in the L-canavanine group. The endotoxin-induced increases in venous levels of NO-hemoglobin were significantly inhibited by L-canavanine or L-NAME. These data indicate that the beneficial hemodynamic effects of L-canavanine are associated with inhibition of the enhanced formation of NO by inducible NO synthase in a rat model of endotoxin shock. L-Canavanine is a potential agent in the treatment of endotoxin shock.

Reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor-V: function, thermodynamic stability, and NMR solution structure

Reactive-site (Lys44-Asp45 peptide bond) hydrolyzed Cucurbita maxima trypsin inhibitor-V (CMTI-V*) was prepared and characterized: In comparison to the intact form, CMTI-V* exhibited markedly reduced inhibitory properties and binding affinities toward trypsin and human blood coagulation factor XIIa. The equilibrium constant of trypsin-catalyzed hydrolysis, Khyd, defined as [CMTI-V*]/[CMTI-V], was measured to be approximately 9.4 at 25 degrees C (delta G degrees = -1.3 kcal.mol-1). From the temperature dependence of delta G degrees, the following thermodynamic parameters were estimated: delta H degrees = 1.6 kcal.mol-1 and delta S degrees = 9.8 eu. In order to understand the functional and thermodynamic differences between the two forms, the three-dimensional solution structure of CMTI-V* was determined by a combined approach of NMR, distance geometry, and simulated annealing methods. Thus, following sequence-specific and stereospecific resonance assignments, including those of beta-, gamma-, delta-, and epsilon-hydrogens and valine methyl hydrogens, 809 interhydrogen distances and 123 dihedral angle constraints were determined, resulting in the computation and energy-minimization of 20 structures for CMTI-V*. The average root mean squared deviation in position for equivalent atoms between the 20 individual structures and the mean structure obtained by averaging their coordinates is 0.67 +/- 0.15 A for the main chain atoms and 1.19 +/- 0.23 A for all the non-hydrogen atoms of residues 5-40 and residues 48-67.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of the yeast mutation rft1-1 by human p53

Mutations in the gene encoding p53 have been found to be the most common genetic alterations in human cancer, p53 is thought to exert its function of tumor suppression through inhibition of cell proliferation or induction of apoptosis in response to DNA damage. Although there have been no proteins homologous to p53 identified in lower eucaryotic organisms, it is known that overexpression of wild-type human p53 can inhibit cell growth of Schizosaccharomyces pombe and Saccharomyces cerevisiae (Bischoff et al., 1992; Nigro et al., 1992), suggesting that certain aspects of p53 function may manifest or exist in yeast. In an attempt to identify the p53-like proteins in the yeast S. cerevisiae, we isolated a mutant that requires wild-type p53 for its viability. The mutant, rft1-1, is defective in cell cycle progression and arrests before mitosis when p53 protein is depleted. Genetic and biochemical studies show that p53 suppresses the rft1-1 mutation by forming a protein-protein complex with the Rft1 protein.

Solution conformations of proline rings in proteins studied by NMR spectroscopy

Three different conformations of proline rings in a protein in solution, Up, Down and Twist, have been distinguished, and stereospecific assignments of the pyrrolidine beta-, gamma- and delta-hydrogens have been made on the basis of 1H-1H vicinal coupling constant patterns and intraresidue NOEs. For all three conformations, interhydrogen distances in the pairs alpha-beta 3, beta 3-gamma 3, beta 2-gamma 2, gamma 2-delta 2, and gamma 3-delta 3 (2.3 A) are shorter than those in the pairs alpha-beta 2, beta 2-gamma 3, beta 3-gamma 2, gamma 2-delta 3, and gamma 3-delta 2 (2.7-3.0 A), resulting in stronger NOESY cross peaks. For the Up conformation, the beta 3-gamma 2 and gamma 2-delta 3 spin-spin coupling constants are small (< 3 Hz), and weak cross peaks are obtained in a short-mixing-time (10 ms) TOCSY spectrum; all other vicinal coupling constants are in the range 5-12 Hz, and result in medium to strong TOCSY cross peaks. For the Down form, the alpha-beta 2, beta 2-gamma 3, and gamma 3-delta 2 vicinal coupling constants are small, leading to weak TOCSY cross peaks; all other couplings again are in the range 5-12 Hz, and result in medium to strong TOCSY cross peaks. In the case of a Twist conformation, dynamically averaged coupling constants are anticipated. The procedure has been applied to bovine pancreatic trypsin inhibitor and Cucurbita maxima trypsin inhibitor-V, and ring conformations of all prolines in the two proteins have been determined.

A practical method for stereospecific assignments of gamma- and delta-methylene hydrogens via estimation of vicinal 1H-1H coupling constants

Stereospecific assignments are made for gamma- and delta-methylene hydrogens in a protein by means of estimation of vicinal 1H-1H spin-spin coupling constants from a short-mixing-time TOCSY experiment. 3J alpha beta coupling constants, as measured from a P.E. COSY map, are shown to be well correlated with alpha-beta cross-peak intensities of a short-mixing-time (10 ms) TOCSY map. The procedure is illustrated by application to a trypsin-inhibitor protein (M(r) approximately 7 Kd). Thus, gamma-methylene hydrogens of isoleucine residues have been stereospecifically assigned on the basis of 3J beta gamma 1H-1H coupling patterns and intraresidue cross-peak intensities in a NOESY map; gamma-hydrogens of other residues, such as lysine and arginine, have been stereospecifically assigned solely on the basis of cross-peak intensity patterns resulting from coupling of two beta-hydrogens to two gamma-hydrogens, and in conjunction with stereospecific assignments of beta-methylene hydrogens. However, intraresidue NOE intensities are needed if one or two pairs of coupling constants cannot be estimated because of cross peaks either overlapping or occurring proximal to the diagonal. The delta-methylene hydrogens have been stereospecifically assigned on the basis of coupling between two gamma-hydrogens and two delta-hydrogens, in combination with stereospecific assignments of gamma-hydrogens. Stereospecific assignments of side chains should contribute to the overall precision and accuracy of NMR-determined three-dimensional solution structures of proteins.

Three-dimensional solution structure of Cucurbita maxima trypsin inhibitor-V determined by NMR spectroscopy

The solution structure of Cucurbita maxima trypsin inhibitor-V (CMTI-V), which is also a specific inhibitor of the blood coagulation protein, factor XIIa, was determined by 1H NMR spectroscopy in combination with a distance-geometry and simulated annealing algorithm. Sequence-specific resonance assignments were made for all the main-chain and most of the side-chain hydrogens. Stereospecific assignments were also made for some of the beta-, gamma-, delta-, and epsilon-hydrogens and valine methyl hydrogens. The ring conformations of all six prolines in the inhibitor were determined on the basis of 1H-1H vicinal coupling constant patterns; most of the proline ring hydrogens were stereospecifically assigned on the basis of vicinal coupling constant and intraresidue nuclear Overhauser effect (NOE) patterns. Distance constraints were determined on the basis of NOEs between pairs of hydrogens. Dihedral angle constraints were determined from estimates of scalar coupling constants and intraresidue NOEs. On the basis of 727 interproton distance and 111 torsion angle constraints, which included backbone phi angles and side-chain chi 1, chi 2, chi 3, and chi 4 angles, 22 structures were calculated by a distance geometry algorithm and refined by energy minimization and simulated annealing methods. Both main-chain and side-chain atoms are well-defined, except for a loop region, two terminal residues, and some side-chain atoms located on the molecular surface. The average root mean squared deviation in the position for equivalent atoms between the 22 individual structures and the mean structure obtained by averaging their coordinates is 0.58 +/- 0.06 A for the main-chain atoms and 1.01 +/- 0.07 A for all the non-hydrogen atoms of residues 3-40 and 49-67. These structures were compared to the X-ray crystallographic structure of another protein of the same inhibitor family-chymotrypsin inhibitor-2 from barley seeds [CI-2; McPhalen, C. A., & James, M. N. G. (1987) Biochemistry 26, 261-269]. The main-chain folding patterns are highly similar for the two proteins, which possess 62% sequence differences. However, major differences are noted in the N- and C-terminal segments, which may be due to the presence of a disulfide bridge in CMTI-V, but not in CI-2.

[A new zoonosis--investigation of Gardnerella vaginalis disease of fox. II. Identification of pathogenic bacteria]

16 strains isolated from aborted foetus and vaginal exeretions of foxes were used for examination of cell morphology including fine structure of the cell wall and septa, test for homolysis, biochemical reactions and analysis of G+C content of the bacterial DNA. The cells are pleomorphic bacilli and coccobacilli, Gram stain reaction appear positive to variable, catalse and oxidase-negative, with a fermentative type of glucose metabolism, giving acetic and lactic acid as the major end products of fermentation. It's differentiated from the human strains of G. vaginalis by its less fastidious in growth requirements and being facultatively anaerobic to aerobic. We propose the name: a new subspecies--Gardnerella vaginalis subsp. fox, the type strain is U80.

[Development of a monoclonal antibody (AF9) to human breast carcinoma]

A monoclonal antibody AF9 (IgG1) was raised against human breast carcinoma by fusing murine myeloma SP2/0 cells with spleen cells from BALB/c mice immunized with cell membrane extracts from primary breast carcinoma. Immunohistochemical staining using the antibody showed reactivity in 19 out of 20 breast carcinoma tissues and in some nonbreast carcinomas such as hepatic, ovarian, lung, colon, and gastric carcinoma tissues. But no staining was observed in either normal tissues or other carcinomas. By immunological treatment, the antigen recognized by AF9 was referred to be glycoprotein with lipid component, and Western blotting revealed that its molecular weight is 51, 56, 67 and 73kd.

Characteristics of the paramagnetic 1H-NMR spectra of the ferricytochrome c-551 family

Heme proton resonances have been assigned for ferricytochromes c-551 isolated from four distinct species of bacteria. While the available structure information indicates that the four cytochromes have very similar conformations in solution, including the chirality of the methionine ligand sulfur bond, the chemical shifts of the paramagnetically shifted resonances are surprisingly different, more so than has been previously reported for a homologous series of ferricytochromes. The resonances are contrasted in terms of chemical shift and the temperature dependence of the shift, which gives rise to a very strong anti-Curie effect for some specific protons. Non-methyl heme resonances do display an approximately conserved set of chemical shifts, but the heme methyl groups demonstrate a wide range of values. The 12(1) heme methyl group is always the highest frequency heme methyl, but the relative positions of the other methyl groups may change. The 7(1) heme methyl group always displayed strong anti-Curie behavior, while the 12(1) methyl group displayed normal Curie behavior. The behavior of the other methyl groups was variable. Possible reasons for the range of observations will be discussed. In spite of their NMR differences, all the ferricytochromes c-551 demonstrated comparable electron-transfer rates to a membrane-bound cytochrome reductase system.

Solution conformation of cytochrome c-551 from Pseudomonas stutzeri ZoBell determined by NMR

1H NMR spectroscopy and solution structure computations have been used to examine ferrocytochrome c-551 from Pseudomonas stutzeri ZoBell (ATCC 14405). Resonance assignments are proposed for all main-chain and most side-chain protons. Stereospecific assignments were also made for some of the beta-methylene protons and valine methyl protons. Distance constraints were determined based upon nuclear Overhauser enhancements between pairs of protons. Dihedral angle constraints were determined from estimates of scalar coupling constants and intra-residue NOEs. Twenty structures were calculated by distance geometry and refined by energy minimization and simulated annealing on the basis of 1012 interproton distance and 74 torsion angle constraints. Both the main-chain and side-chain atoms are well defined except for two terminal residues, and some side-chain atoms located on the molecular surface. The average root mean squared deviation in the position for equivalent atoms between the 20 individual structures and the mean structure obtained by averaging their coordinates is 0.56 +/- 0.10 A for the main-chain atoms, and 0.95 +/- 0.09 A for all nonhydrogen atoms of residue 3 to 80 plus the heme group. The average structure was compared with an analogous protein, cytochrome c-551 from pseudomonas stutzeri. The main-chain folding patterns are very consistent, but there are some differences, some of which can be attributed to the loss of normally conserved aromatic residues in the ZoBell c-551.

Effects of free radical scavengers, methylprednisolone, and ulinastatin on acute xanthine and xanthine oxidase-induced lung injury in rats

We investigated the role of free radicals, especially from activated neutrophils, in acute xanthine and xanthine oxidase-induced lung injury in rats. We evaluated the effects of intravenously administered intracellular and extracellular free radical scavengers (for O2-., H2O2, and .OH), methylprednisolone (MP), and Ulinastatin (UST, a protease inhibitor), on this animal model of lung injury. At 5 min prior to the intrabronchial injection of a mixture of xanthine (X, 100 nmol) and xanthine oxidase (XO, 1 unit) used to induce unilateral lung damage, rats were pretreated intravenously with superoxide dismutase (SOD, 40 mg/kg), SOD (40 mg/kg) plus catalase (CAT, 30 mg/kg), dimethylthiourea (DMTU, 500 mg/kg), N-2-mercaptopropionyl glycine (MPG, 20 mg/kg), MP, 30 mg/kg, and UST, 50,000 units/kg. Each scavenger was infused intravenously at one-half the initial dose for 20 min after intrabronchial injection; 3 hr later, we examined the wet/dry lung weight ratios and the levels of thiobarbituric acid-reactive substances (TBARS) in lung tissue. Intrabronchial injection of the X/XO mixture markedly increased wet/dry lung weight ratios and lung tissue content of TBARS. Histopathologic changes were observed in the injected lung as well. Pretreatment with SOD + CAT, DMTU, and UST significantly reduced the increases in wet/dry lung weight ratios and lung tissue content of TBARS induced by the intrabronchial injection of the X/XO mixture. Our data suggest indirectly that free radicals (H2O2, .OH) and proteases from activated neutrophils may contribute, in part, to the lung damage induced by the O2-.-generating system of xanthine and xanthine oxidase.

[A new species of Pseudomonas]

A strain No. 9191 isolated from fruit juice mineral drink is gram-negative short-rod. It differs from reported species of Pseudomonas in morphological, physiological and biochemical characteristics. Main characteristics of No. 9191 are single polar flagelled, oxidase and catalase positive, no acid from glucose but producing alkali, nitrate reduced to nitrite, inability to hydrolize gelatin and starch, arginine dihydrolase absent, no growth in presence of 0.85% NaCl. The G+C mol% of DNA is 65.15. It is named Pseudomonas halosensibilis Zou & Cai nov. sp. by the sensibility property for salt.

[Radioligand binding assay of PHSA receptor on hepatocytes]

The radioligand binding assay of PHSA receptor on hepatocytes of 7 adults is reported. The presence of PHSA receptor was demonstrated in all the 7 adults, though the individual difference of the Kds and binding capacities among them was distinct with a higher standard derivation. The mean values of the Kds and binding capacities were as follows: Kd1 = 9.6769 +/- 5.2767fm-2, C1 = 86.1468 +/- 46.4129fm/micrograms; Kd2 = 103.1810 +/- 56.4770fm-2, C2 = 261.5302 +/- 175.9094fm/micrograms. The Scatchard plot was a curve which indicated the PHSA receptor on the hepatocyte was composed of two binding sites of different affinities and capacities. The possible mechanism and significance of PHSA receptor in the hepatotrophism are also discussed.

Investigation of the structure of oxidized Pseudomonas aeruginosa cytochrome c-551 by NMR: comparison of observed paramagnetic shifts and calculated pseudocontact shifts

Extensive main-chain and side-chain assignments are reported for the 1H NMR spectrum of ferricytochrome c-551 from Pseudomonas aeruginosa at 323 K and pH 5.2. These were obtained by sequential assignments of two-dimensional scalar and dipolar correlation spectra. The low-spin (S = 1/2) ferric iron in the oxidized state gives rise to extensive contact and pseudocontact shifts for resonances in the ferricytochrome. Total redox-state-dependent shifts were computed by comparison to the previously assigned ferrocytochrome c-551. A set of 179 firmly assigned protons was selected that were expected to experience only pseudocontact shift contributions in the oxidized form. The pseudocontact shifts were calculated for the set by a standard model [Williams, G., Clayden, N. J., Moore, G. R., & Williams, R. J. P. (1985) J. Mol. Biol. 183, 447-460] using the atomic coordinates from the X-ray crystallographic determination of the oxidized form [Matsuura, Y., Takano, T., & Dickerson, R. E. (1982) J. Mol. Biol. 156, 389-409], and effective anisotropy and geometric factors were adjusted to minimize the sum of the squared differences between observed redox-state shifts and calculated pseudocontact shift contributions. The root-mean-squared deviation with the optimized parameters was 0.12 ppm. The optimized model was then used to calculate pseudocontact shifts for other assigned protons outside the basic set. The overall agreement and the lack of any systematic discrepancies provide evidence that there are no major structural differences among the solution and crystal conformations of the oxidized and reduced forms, within the inherent resolution of this computational approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for the structure of the active site heme P460 in hydroxylamine oxidoreductase of Nitrosomonas

Hydroxylamine oxidoreductase (HAO) is responsible for the oxidation of hydroxylamine to nitrite in nitrification by Nitrosomonas europaea. It has an alpha n subunit structure and eight covalently bound hemes per subunit. Seven of these have visible spectra indistinguishable from heme c. The eighth, designated as P460, has unusual visible spectroscopic features in the enzyme and in a heme-containing proteolytic fragment. Its structure has not been previously determined. Enzymatic digestions of HAO were performed, and various proteolytic fragments were purified. Mass spectrometry confirmed the presence of authentic heme c in some fragments, that is, iron protoporphyrin IX cross-linked by two thioether bonds to cysteine residues. It was possible to detect the presence of the P460 pigment in some fragments, based upon the sensitivity of this pigment to treatment of the holoenzyme with hydrogen peroxide. A proteolytic fragment produced by sequential digestion with trypsin and pronase was shown to contain heme c and a hydrogen peroxide-sensitive heme with an unusual visible spectrum. This fragment contained two covalently cross-linked peptides. Mass spectrometry and NMR indicated that the P460 heme was iron protoporphyrin IX covalently bonded by two thioether bridges to peptide, but in addition there was a new, third covalent bond between a meso heme carbon and an aromatic ring carbon on a tyrosyl residue. The new covalent bond has been tentatively assigned to the C2 carbon of the tyrosyl ring and the 5-meso heme carbon (IUPAC-IUB tetrapyrrole nomenclature), although this location requires further proof.