[One simple and efficient method for purification of IgG McAb from mice ascites: caprylic acid/ammonium sulfate precipitation]

Several ascitic IgG McAbs were purificated by caprylic acid/ammonium sulfate precipitation (CA-AS), ammonium sulfate precipitation (AS) and SPA affinity chromatography. Purity of IgG purificated by CA-AS ranged from 87% to 91%, higher than that obtained by CA (65%-70%), lower than that obtained by SPA affinity chromatography (100%). The yield of IgG purificated by CA-AS ranged from 4.8 g/L to 5.5 g/L, lower than that obtained by CA (7.0-7.9 g/L), more higher than that obtained by SPA affinity chromatography (0.6 g/L). The recovery of IgG purificatied by CA-AS ranged from 39.0% to 44.4%, lower than that obtained by CA (56.0%-65.0%), more higher than that obtained by SPA affinity chromatography (7.4%). The ELISA titer of 4E2 or H6McAb was not impaired by purification of CA-AS. The above results suggested that CA-AS is one simple, efficient, rapid and low-cost method for purification of IgG McAb from ascitic fluid.

NMR structure and mutagenesis of the inhibitor-of-apoptosis protein XIAP

The inhibitor-of-apoptosis (IAP) family of proteins, originally identified in baculoviruses, regulate programmed cell death in a variety of organisms. IAPs inhibit specific enzymes (caspases) in the death cascade and contain one to three modules of a common 70-amino-acid motif called the BIR domain. Here we describe the nuclear magnetic resonance structure of a region encompassing the second BIR domain (BIR2) of a human IAP family member, XIAP (also called hILP or MIHA). The structure of the BIR domain consists of a three-stranded antiparallel beta-sheet and four alpha-helices and resembles a classical zinc finger. Unexpectedly, conserved amino acids within the linker region between the BIR1 and BIR2 domains were found to be critical for inhibiting caspase-3. The absence or presence of these residues may explain the differences in caspase inhibition observed for different truncated and full-length IAPs. Our data further indicate that these residues may bind to the active site and that the BIR domain may interact with an adjacent site on the enzyme.

Recovery of the yeast cell cycle from heat shock-induced G(1) arrest involves a positive regulation of G(1) cyclin expression by the S phase cyclin Clb5

In the yeast Saccharomyces cerevisiae, heat shock stress induces a variety of cellular responses including a transient cell cycle arrest before G(1)/S transition. Previous studies have suggested that this G(1) delay is probably attributable to a reduced level of the G(1) cyclin gene (CLN1 and CLN2) transcripts. Here we report our finding that the G(1) cyclin Cln3 and the S cyclin Clb5 are the key factors required for recovery from heat shock-induced G(1) arrest. Heat shock treatment of G(1) cells lacking either CLN3 or CLB5/CLB6 functions leads to prolonged cell cycle arrest before the initiation of DNA synthesis, concomitant with a severe deficiency in bud formation. The inability of the clb5 clb6 mutant to resume normal budding after heat shock treatment is unanticipated, since the S phase cyclins are generally thought to be required mainly for initiation of DNA synthesis and have no significant roles in bud formation in the presence of functional G(1) cyclins. Further studies reveal that the accumulation of G(1) cyclin transcripts is markedly delayed in the clb5 clb6 mutant following heat shock treatment, indicating that the CLN gene expression may require Clb5/Clb6 to attain a threshold level for driving the cell cycle through G(1)/S transition. Consistent with this assumption, overproduction of Clb5 greatly enhances the transcription of at least two G(1) cyclin genes (CLN1 and CLN2) in heat-shocked G(1) cells. These results suggest that Clb5 may positively regulate the expression of G(1) cyclins during cellular recovery from heat shock-induced G(1) arrest. Additional evidence is presented to support a role for Clb5 in maintaining the synchrony between budding and DNA synthesis during normal cell division as well.

[Genetic polymorphisms of serum orosomucoid in Han population in Nanjing of China]

OBJECTIVE

To determine the genetic polymorphisms of serum orosomucoid (ORM) in Han population in Nanjing of China and provide genetic data for studying the individual variance in the plasma protein binding of weak alkaline drugs.

METHODS

The desialylated sera from 220 unrelated subjects were analyzed by isoelectric focusing on polyacrylamide gels followed by immunoblotting.

RESULTS

The band patterns of ORM showed that the polymorphism of the structural locus ORM1 was controlled by three codominant autosomal alleles, ORM1*F1, ORM1*F2 and ORM1*S, which presented five phenotypes, ORM1 F1(47.27%), ORM1 S(5.46%), ORM1 F1F2 (3.18%), ORM1 F1S(43.64%), and ORM1 F2S(0.45%). The allele frequencies were: ORM1*F1=0.7068, ORM1*F2=0.0182, ORM1*S=0.2750.

CONCLUSION

The ORM1 locus is polymorphic and the ORM2 locus is monomorphic in sera from the Han people in Nanjing of China.

Accurate measurement of H(N)-H(alpha) residual dipolar couplings in proteins

A method for accurately measuring H(N)-H(alpha) residual dipolar couplings is described. Using this technique, both the sign and magnitude of the coupling can be determined easily. Residual dipolar coupling between H(N)(i)-H(alpha)(i) and H(N)(i)-H(alpha)(i-1) were measured for the FK506 binding protein complexed to FK506. The experimental values were in excellent agreement with predictions based on an X-ray crystal structure of the protein/ligand complex, suggesting that these residual dipolar couplings will provide accurate structural constraints for the refinement of protein structures determined by NMR.

[Studies on the parasites of Paris polyphylla var. yunnanensis]

Two bacteria and three fungi were isolated from the hypogeal stems of Paris polyphylla var. yunnanensis. The bacteria were identified as Bacillus cereus and Pseudomonas alcaligenes, and the fungi were identified as Periconia sp., Pachnocybe albida and Hormomyces paridiphilus. The results on liquid culture of B. cereus, P. alcaligenes and H. paridiphilus indicated that the colloidization and polysaccharide content increasing in hypogeal stems of P. polyphylla var. yunnanensis were due to the extracellular polysaccharide secretion of the parasitical fungus H. paridiphilus.

[The extraction of DNA from milligram amounts of wild mountain ginseng tissues]

OBJECTIVE

To keep wild mountain ginseng, a rare medicinal remedy, as intact as possible when extracting DNA from it, a new way to extract DNA has been explored.

METHOD

The CTAB method was improved and a simple and direct way was developed.

RESULT

From 0.001 g of dried samples of ginseng root DNA was obtained in an amount up to 2.25 micrograms.

CONCLUSION

The RAPD fingerprinting generated by this DNA is as good as that by CTAB method. This new method may also be used for extraction of other precious Chinese medicinal materials.

[Effect of antioxidant vitamins on lipid peroxide injury of aortic endothelial cells induced by oxidatively modified low-density lipoprotein in vitro]

The effect of antioxidant vitamins including vitamin E, vitamin C and beta-carotene on lipid peroxidation injury of aortic endothelial cells induced by oxidatively modified low density lipoprotein (oxLDL) were observed. Bovine aortic endothelial cells were incubated in culture media with antioxidant vitamins for 12 hours, and then with oxLDL (0.1 g/L) for 24 hours respectively. The results showed that the malondialdehyde (MDA) content in culture media of the groups with oxLDL was significantly higher than those of groups with vitamin E, vitamin C and beta-carotene alone. The number of HL60 monocyte cells adhered to bovine aortic endothelial cells was obviously higher in oxLDL groups than those in groups with only antioxidant vitamins. This study indicated that antioxidant vitamins are protective on vascular from injury induced by oxLDL, including decreasing lipid peroxidation and reducing adherence of monocyte cells on endothelia and seemed to be promising in the prevention of atherosclerosis.

The sequential analysis of trisomy 12 in B-cell chronic lymphocytic leukaemia

In this longitudinal study we evaluated the clinical significance of screening for trisomy 12 by fluorescence in situ hybridization (FISH) and correlated these findings with survival, disease progression and need for treatment. Interphase FISH was performed on 85 patients in 1993/94 and repeated on 41 patients in 1996/97. Over the 4-year period there was no significant change in the percentage of trisomic cells, even in patients with disease progression. Overall survival and requirement for treatment were similar for patients with and without FISH-defined trisomy 12.

Solution conformation of ferricytochrome c-551 from Pseudomonas stutzeri substrain ZoBell

The main chain protons and the majority of side chain protons have been assigned for the ferric form of Pseudomonas stutzeri substrain ZoBell (American Type Culture Collection 14405) cytochrome c-551. The chemical shifts were compared to those for the ferrous protein to determine the pseudocontact shift contribution. These observed values were compared to contributions calculated from the atomic coordinates of the ferrous cytochrome and an optimized effective room temperature g-tensor centered on the paramagnetic ferric iron. The agreement between observed and calculated values indicates that the conformations of the two forms are highly similar.

Regulation of the actin cytoskeleton organization in yeast by a novel serine/threonine kinase Prk1p

Normal actin cytoskeleton organization in budding yeast requires the function of the Pan1p/ End3p complex. Mutations in PAN1 and END3 cause defects in the organization of actin cytoskeleton and endocytosis. By screening for mutations that can suppress the temperature sensitivity of a pan1 mutant (pan1-4), a novel serine/threonine kinase Prk1p is now identified as a new factor regulating the actin cytoskeleton organization in yeast. The suppression of pan1-4 by prk1 requires the presence of mutant Pan1p. Although viable, the prk1 mutant is unable to maintain an asymmetric distribution of the actin cytoskeleton at 37 degreesC. Consistent with its role in the regulation of actin cytoskeleton, Prk1p localizes to the regions of cell growth and coincides with the polarized actin patches. Overexpression of the PRK1 gene in wild-type cells leads to lethality and actin cytoskeleton abnormalities similar to those exhibited by the pan1 and end3 mutants. In vitro phosphorylation assays demonstrate that Prk1p is able to phosphorylate regions of Pan1p containing the LxxQxTG repeats, including the region responsible for binding to End3p. Based on these findings, we propose that the Prk1 protein kinase regulates the actin cytoskeleton organization by modulating the activities of some actin cytoskeleton-related proteins such as Pan1p/End3p.

Solution structure of the His12 --> Cys mutant of the N-terminal zinc binding domain of HIV-1 integrase complexed to cadmium

The solution structure of His12 --> Cys mutant of the N-terminal zinc binding domain (residues 1-55; IN(1-55)) of HIV-1 integrase complexed to cadmium has been solved by multidimensional heteronuclear NMR spectroscopy. The overall structure is very similar to that of the wild-type N-terminal domain complexed to zinc. In contrast to the wild-type domain, however, which exists in two interconverting conformational states arising from different modes of coordination of the two histidine side chains to the metal, the cadmium complex of the His12 --> Cys mutant exists in only a single form at low pH. The conformation of the polypeptide chain encompassing residues 10-18 is intermediate between the two forms of the wild-type complex.

Solution structure of the cellular factor BAF responsible for protecting retroviral DNA from autointegration

The solution structure of the human barrier-to-autointegration factor, BAF, a 21,000 Mr dimer, has been solved by NMR, including extensive use of dipolar couplings which provide a priori long range structural information. BAF is a highly evolutionarily conserved DNA binding protein that is responsible for inhibiting autointegration of retroviral DNA, thereby promoting integration of retroviral DNA into the host chromosome. BAF is largely helical, and each subunit is composed of five helices. The dimer is elongated in shape and the dimer interface comprises principally hydrophobic contacts supplemented by a single salt bridge. Despite the absence of any sequence similarity to any other known protein family, the topology of helices 3-5 is similar to that of a number of DNA binding proteins, with helices 4 and 5 constituting a helix-turn-helix motif. A model for the interaction of BAF with DNA that is consistent with structural and mutagenesis data is proposed.

[Studies on synthesis and analgesic activities of bifentanyl derivatives]

In order to look for potent analgesic compounds and to study the relationships between structures and activities, twenty bifentanyl derivatives were synthesized and their analgesic activities were tested. The structures of the compounds were confirmed by spectral analysis and elemental analysis. Compounds IIa and IIb showed strong analgesic activities in preliminary pharmacological test. Further pharmacological examinations are in progress.

[Application of stress urethral pressure profile for diagnosis and treatment of stress incontinence]

OBJECTIVE

To apply the stress urethral pressure profile (SUPP) to diagnose the genuine stress incontinence (GSI) and to evaluate the results of treatment.

METHOD

22 patients with GSI underwent SUPP and rest urethral pressure profile (RUPP) using Dantec Menuet.

RESULT

The results showed that the pressure transmission ratio (PTR) was 0.68 +/- 0.06, and urethral close pressure (UCP) was -0.62 +/- 0.22 kPa in 22 patients. PTR and UCP raised significantly after operation in 5 patients, P < 0.01. The results of SUPP were compared with those RUPP.

CONCLUSION

SUPP is important in both diagnosis and evaluation of GSI, although some limitation exists. To improve the level of diagnosis, it should be combined with other method in clinical use.

Three-dimensional solution structure of the 44 kDa ectodomain of SIV gp41

The solution structure of the ectodomain of simian immunodeficiency virus (SIV) gp41 (e-gp41), consisting of residues 27-149, has been determined by multidimensional heteronuclear NMR spectroscopy. SIV e-gp41 is a symmetric 44 kDa trimer with each subunit consisting of antiparallel N-terminal (residues 30-80) and C-terminal (residues 107-147) helices connected by a 26 residue loop (residues 81-106). The N-terminal helices of each subunit form a parallel coiled-coil structure in the interior of the complex which is surrounded by the C-terminal helices located on the exterior of the complex. The loop region is ordered and displays numerous intermolecular and non-sequential intramolecular contacts. The helical core of SIV e-gp41 is similar to recent X-ray structures of truncated constructs of the helical core of HIV-1 e-gp41. The present structure establishes unambiguously the connectivity of the N- and C-terminal helices in the trimer, and characterizes the conformation of the intervening loop, which has been implicated by mutagenesis and antibody epitope mapping to play a key role in gp120 association. In conjunction with previous studies, the solution structure of the SIV e-gp41 ectodomain provides insight into the binding site of gp120 and the mechanism of cell fusion. The present structure of SIV e-gp41 represents one of the largest protein structures determined by NMR to date.

[Determination of copper, iron and zinc in hair of mentally retarded children by oscillopolarography]

The oscillopolarographic method (proposed by Ding Jianwen)for the simulltaneous determination of copper, iron and zinc in hair was further studied and applied to the investigation of copper, iron, zinc content in hair samples from 46 mentally retarded children and 49 healthy children. For copper, iron, zinc, the detection limits were 0.03, 0.03, 0.01 microgram/ml, dynamic range 0.05-15, 0.05-2.5, 0.2-10 micrograms/ml, the RSD of sample analysis 3.2%, 3.3%, 2.4%, the recoveries 96: 0%-105.2%, 2%, 97.3%-109.0%, 94.7%-107.7%, respectively. The difference between the results for the same sample by this method and the atomic absorption spectroscopic method was no statistical significance. The results showed that the copper content and iron content of hair samples from mentally retarded children were significantly lower than those of healthy children.

An efficient and cost-effective isotope labeling protocol for proteins expressed in Escherichia coli

A cost-effective protocol for uniform 15N and/or 13C isotope labeling of bacterially expressed proteins is presented. Unlike most standard protocols, cells are initially grown in a medium containing nutrients at natural abundance and isotopically labeled nutrients are only supplied at the later stages of growth and during protein expression. This permits the accumulation of a large cell mass without the need to employ expensive isotopically labeled nutrients. The abrupt decrease in oxygen consumption that occurs upon complete exhaustion of essential nutrients is used to precisely time the switch between unlabeled and labeled nutrients. Application of the protocol is demonstrated for wild-type and a mutant of the N-terminal zinc-binding domain of HIV-1 integrase.

Solution structure of the Mu end DNA-binding ibeta subdomain of phage Mu transposase: modular DNA recognition by two tethered domains

The phage Mu transposase (MuA) binds to the ends of the Mu genome during the assembly of higher order nucleoprotein complexes. We investigate the structure and function of the MuA end-binding domain (Ibetagamma). The three-dimensional solution structure of the Ibeta subdomain (residues 77-174) has been determined using multidimensional NMR spectroscopy. It comprises five alpha-helices, including a helix-turn-helix (HTH) DNA-binding motif formed by helices 3 and 4, and can be subdivided into two interacting structural elements. The structure has an elongated disc-like appearance from which protrudes the recognition helix of the HTH motif. The topology of helices 2-4 is very similar to that of helices 1-3 of the previously determined solution structure of the MuA Igamma subdomain and to that of the homeodomain family of HTH DNA-binding proteins. We show that each of the two subdomains binds to one half of the 22 bp recognition sequence, Ibeta to the more conserved Mu end distal half (beta subsite) and Igamma to the Mu end proximal half (gamma subsite) of the consensus Mu end-binding site. The complete Ibetagamma domain binds the recognition sequence with a 100- to 1000-fold higher affinity than the two subdomains independently, indicating a cooperative effect. Our results show that the Mu end DNA-binding domain of MuA has a modular organization, with each module acting on a specific part of the 22 bp binding site. Based on the present binding data and the structures of the Ibeta and Igamma subdomains, a model for the interaction of the complete Ibetagamma domain with DNA is proposed.

[Improved MTT colorimetric assay for serum TNF activity]

The activity of serum tumor necrosis factor(TNF) is known to be related with the mechanism and prognosis of many diseases. The aim of this experiment was to look for an economic and reliable method for assaying the activity of serum TNF. We used the neutrophil solventor 20% SDS-50% DMF instead of the acidity solventor 0.04 mol/l acidified isopropy alcohol and established an improved 3-(4,5-dimethyl thiazoly)2,5-diphenyl-tetrazolium bromide (MTT) colorimetric assay for measuring the amount and function of living cell. We used this improved MTT colorimetric assay for measuring TNF activity of peripheral blood serum of healthy persons. It avoided the deposition of the protein in serum and medium and showed more repeatability, as compared with the conventional MTT colorimetric assay. The results showed: when the activity of target cell(TC)-L929 is > or = 95%, the density of TC is > or = 1 x 10(2)/well and the number of living cells in each well is positively correlated with the OD volume (OD570nm-OD630nm of purple formazan metabolite of MTT solution(r = 0.87, P < 0.01); when the density of TC is 5 x 10(4)/well, the level standard of TNF in each well is negatively correlated with the OD volume (OD570nm-OD630nm)r = 0.79, P < 0.01). Using this method, we measured the TNF activity of 20 healthy persons' peripheral blood serum. The mean +/- s of TNF activity is 20.95 +/- 3.2 IU/ml. This method is dependable, easy-to-do and economic, it has good repeatability within 3-12 hours.

[Identification of the anti-rIL-1ra McAb]

Using dot-immuno-blot and Western blotting techniques, we have identified the specificity of anti-rIL-1ra McAbs. The results showed that the anti-rIL-1ra McAb 2E4 specifically reacted with rIL-1ra, from which the recognizing signal of dot-immunoblot was significantly positive (+2) and a single rIL-1ra protein band (20 kd) was clearly recognized by Western blotting. The control results of PcAb recognization have further proved the high sensitivity of Western blotting and high specificity of rIL-1ra McAb 2E4. The successful identification of rIL-1ra McAb 2E4 will be helpful to further understand the biologic effects, especially the pro-inflammatory properties, to study the change of rIL-1ra level during inflammation, and to instruct the clinical use of rIL-1ra.

Determination of the secondary structure and global topology of the 44 kDa ectodomain of gp41 of the simian immunodeficiency virus by multidimensional nuclear magnetic resonance spectroscopy

The gp41 protein of the human (HIV) and simian (SIV) immunodeficiency viruses is part of the envelope glycoprotein complex gp41/gp120 which plays an essential role in viral infection. We present a multidimensional NMR study on the trimeric 44 kDa soluble ectodomain of SIV gp41 (e-gp41), comprising residues 27 to 149. Despite the large molecular weight and very limited spectral dispersion, complete backbone 1H, 13C, 13CO and 15N assignments have been made using a combination of triple resonance experiments on uniformly 13C/15N and 2H/13C/15N-labeled samples. The secondary structure of SIV e-gp41, derived on the basis of 13C chemical shifts, NH exchange rates, medium range nuclear Overhauser enhancements (NOE), and 3JHNalpha coupling constants, consists of a 49 residue helix at the N terminus (residues 29 to 77) and a 40 residue helix at the C terminus (residues 108 to 147), connected by a 30 residue loop which does not display any of the characteristics of regular secondary structure. The cross-peak intensities of the loop region in scalar correlation experiments suggests that it is more mobile than the core helical regions. The presence, however, of numerous long range NOEs, both intra and inter-subunit, within the loop indicates that it adopts a well-defined structure in which the loops from the three subunits interact with each other. Based on a number of long range intra and inter-subunit NOEs, a topological model is presented for the symmetric SIV e-gp41 trimer in which the N-terminal helices are packed within the protein interior in a parallel trimeric coiled-coil arrangement, while the C-terminal helices are located on the protein exterior, oriented antiparallel to the N-terminal helices.

[Study on PHSAr gene expression of HBV in normal human hepatocytes]

Based on the sequence of Hepatitis B Virus (type adr) (HBV) Pre S2 region, we synthesized a pair of PCR primers. After a test of specificity, the primers were employed to amplify the postulated transcripts of PHSAr gene in the liver samples of 3 normal human subjects. By RT-PCR and RNA-PCR, all amplification results were positive, while those from corresponding skeleton muscle controls were negative. It suggests that HBV Pre S2 region should be to some extent homologous to PHSAr gene exon(s). It also indicates that PHSAr gene is in expression at transcriptional level, but not in expression in tissues (e.g. skeleton muscle) un susceptible to HBV infection. Our data further confirm the role of PHSAr in HBV infection of hepatocytes, compared with those from membrane receptor researches.

[Chromosomal aberrations induced in human spermatozoa by mitomycin C]

Human spermatozoa were exposed to Mitomycin C (MM() at the concentrations of 7.5, 15, 3O micrograms/ml for 1 hour respectively before interspecific in vitro fertilization with zona-free hamster ova. The first cleavage metaphases was analyzed to investigate MMC-induced effects on human spermatozoa. The results showed a distinct dose-response relationship in the induction of chromosomal aberrations. The chromatid aberrations were the predominant types in MMC-induced changes. Some chromosome-type aberrations were also observed. This suggested that the induced effects of MMC on human spermatozoa were some different from that of ultraviolet light-like clastogens on somatic cells. 36.89% of MMC-induced aberrations were rejoining-type. This indicated that the DNA repair systems present in golden hamster oocytes were effective in repairing MMC-induced DNA lesions in human spermatozoa.

EH domain proteins Pan1p and End3p are components of a complex that plays a dual role in organization of the cortical actin cytoskeleton and endocytosis in Saccharomyces cerevisiae

Several proteins from diverse organisms have been shown to share a region of sequence homology with the mammalian epidermal growth factor receptor tyrosine kinase substrate Eps15. Included in this new protein family, termed EH domain proteins, are two yeast proteins, Pan1p and End3p. We have shown previously that Pan1p is required for normal organization of the actin cytoskeleton and that it associates with the actin patches on the cell cortex. End3p has been shown by others to be an important factor in the process of endocytosis. End3p is also known to be required for the organization of the actin cytoskeleton. Here we report that Pan1p and End3p act as a complex in vivo. Using the pan1-4 mutant which we isolated and characterized previously, the END3 gene was identified as a suppressor of pan1-4 when overexpressed. Suppression of the pan1-4 mutation by multicopy END3 required the presence of the mutant Pan1p protein. Coimmunoprecipitation and two-hybrid protein interaction experiments indicated that Pan1p and End3p associate with each other. The localization of Pan1p to the cortical actin cytoskeleton became weakened in the end3 mutant at the permissive temperature and undetectable at the restrictive temperature, suggesting that End3p may be important for proper localization of Pan1p to the cortical actin cytoskeleton. The finding that the pan1-4 mutant was defective in endocytosis as severely as the end3 mutant under nonpermissive conditions supports the notion that the association between Pan1p and End3p is of physiological relevance. Together with results of earlier reports, these results provide strong evidence suggesting that Pan1p and End3p are the components of a complex that has essential functions in both the organization of cell membrane-associated actin cytoskeleton and the process of endocytosis.