cAMP-dependent protein kinase and the protein kinase family

The structure of the catalytic subunit of cAMP-dependent protein kinase, the first protein kinase structure to be solved, is reviewed. The general architecture of the enzyme is described as well as the active site regions associated with substrate binding and catalysis. In particular, the unique features of the protein kinase nucleotide fold are outlined. While the catalytic subunit is one of the simplest of the protein kinases, it nevertheless serves as a structural framework for the catalytic core of the entire protein kinase family which now includes over 200 important regulatory enzymes. The essential and conserved features of this core are summarized, and a preliminary model of myosin light-chain kinase, based on the structure of the catalytic subunit, is also discussed.

[Screening of active anti-inflammatory, immunosuppressive and antifertility components from Tripterygium wilfordii. IV. A comparison of the male antifertility activities of 7 diterpene lactone epoxide compounds]

The male antifertility activities under equal toxic dosages 1/10-1/60 LD50 and hemolysin antibody formation parameters under effective threshold dosages respectively of 7 diterpene lactone epoxide compounds extracted from Tripterygium wilfordii (TW) were assayed in mice. The results indicated that among the 7 compounds, 6 (T10, T4, T7, T8, T9 and L2) showed antifertility activities, the effective thresholds of T7, T8, T10 and L2 were below 1/40 LD50, those of T4 and T9 were below 1/60 LD50, while the other one (T11) did not. The above results reconfirm that the antifertility and immunosuppressive activities of all 6 active compounds are inseparable, but the formation of hemolysin antibodies was not inhibited under the total dosages which resulted in antifertility. The lowest dosages which were positive in terms of antifertility activity were 5-28 times lower than those for antiinflammatory activity and 5-12 times lower than those for immunosuppressive activity. And the total dosages necessary for effective immunosuppression were 0.9-1.8 times than the total dosages needed for effective antifertility. Finally, the value for the use of antifertility activity of these compounds, the influence of antifertility on antiinflammatory and immunosuppressive therapy, and the use of mouse models for screening of male antifertility activity are discussed.

[Retinoblastoma-culture in vitro and establishment of cell line]

60 cases of retinoblastoma cells have been cultured in vitro in recent 6 years. 10 of them grew more than 3 months, and one continuous retinoblastoma cell line (SO-Rb50) has been established for more than 3 years. In addition to the degree of malignancy of the tumor cells, selection of tumor tissues, components of culture media, optimal selection of seeding, passage and densities of cells play important roles in the establishment of immortal retinoblastoma cell line.

[Screening of active anti-inflammatory, immunosuppressive and antifertility components of Tripterygium wilfordii. III. A comparison of the antiinflammatory and immunosuppressive activities of 7 diterpene lactone epoxide compounds in vivo]

The half-effective dose(ED50), therapeutic index(TI) and certain safety factor(CSF) of 7 diterpene lactone epoxide compounds with antiinflammatory and immunosuppressive action extracted from Tripterygium wilfordii (TW) were assayed using croton oil-induced ear swelling and hemolysin-antibody formation mouse models. The results indicated that triptolide(T10), tripchlorolide(T4), triptonide(T7), tripdiolide(T8), triptolidenol(T9) and 16-hydroxytriptolide(L2) possessed both anti-inflammatory and immunosuppressive activities, while triptriolide(T11) had antiinflammatory activity only. The TI of the antiinflammatory action of 7 compounds were arranged in following order: T11(greater than 19), T10(17), T9(9.6), T4(9.0), T8(7.3), L2(6.6), T7(5.9), while the TI of the immunosuppressive action of 6 compounds were arranged in following order: T9(30.7), T4(16.7), L2(15.8), T10(13.7), T8(8.8), T7(7.5). The CSF parameters of both the activities of 7 compounds were all higher than 1. In which, the CSF of the immunosuppressive action of T9, T4 and L2 were 7.1, 5.1 and 3.6 respectively. These facts clearly demonstrate that the antiinflammatory and immunosuppressive compounds in TW are pluralistic. These differences among these compounds can be used as one of the bases for the evaluation and selection of these compounds. The above experiments conclude that the practical value of these compounds, however, will also depend on their content and yield rate in the herb, on the degree of difficulty in synthesizing these compounds, and on difficulty involved in the preparation of their derivatives. The future of these compounds will depend on the results of genetic toxicology studies as well.

Case of atypical cyclopia

A case of atypical cyclopia, involving the right eye with double lens, cornea, iris, and ciliary body, is reported. The possible mechanism of the histogenesis is discussed, together with a review of the relevant literature.

The determination of the pKa of histidine residues in proteins by Raman difference spectroscopy

Sensitive Raman difference spectroscopy was used to monitor the protonation and deprotonation of histidine residues in apo-transferrin. We have shown previously that the behavior of small molecules and/or small molecular groups bound to proteins or other large macromolecules can be studied by Raman difference spectroscopy (Yue, K.T. et al. (1989) J. Raman Spectrosc. 20, 541-545). Using this method, we have measured the Raman difference spectra of human transferrin at different pH values with respect to pH 8.9, titrating its various histidine residues. About 12 +/- 2 of the 19 residues were titrated. The pH difference spectrum of transferrin obtained is very similar to that of histidine in solution, but with clear differences in the 1200-1400 cm-1 region. A titration curve with pKa of 6.08 +/- 0.01 fit the data of histidine in solution and a value of 6.56 +/- 0.02 was found for the average value of the 12 histidine residues inside transferrin. The technique has enough sensitivity at present to monitor a single histidine residue in a 130 kDa molecule and to determine the titration curve of one residue in a 40 kDa protein.

A generic algorithm for finding restriction sites within DNA sequences

This paper describes a generic algorithm for finding restriction sites within DNA sequences. The 'genericity' of the algorithm is made possible through the use of set theory. Basic elements of DNA sequences, i.e. nucleotides (bases), are represented in sets, and DNA sequences, whether specific, ambiguous or even protein-coding, are represented as sequences of those sets. The set intersection operation demonstrates its ability to perform pattern-matching correctly on various DNA sequences. The performance analysis showed that the degree of complexity of the pattern matching is reduced from exponential to linear. An example is given to show the actual and potential restriction sites, derived by the generic algorithm, in the DNA sequence template coding for a synthetic calmodulin.

Premercapturic acid metabolites of bromobenzene derived via its 2,3- and 3,4-oxide metabolites

1. A new premercapturic acid metabolite of bromobenzene was isolated from the urine of beta-naphthoflavone-induced rats; using 1H-n.m.r., FAB mass spectrometry and chemical degradation it was identified as S-(2-hydroxy-3-bromocyclohexa-3,5-dienyl)-N-acetylcysteine. 2. Two regioisomeric premercapturic acids apparently derived from bromobenzene-3,4-oxide were isolated as an inseparable 1:1 mixture from the urine of phenobarbital-induced rats and characterized by similar means. 3. Acid dehydration of bromobenzene 3,4- and 4,3-premercapturic acids (mixture) afforded only p-bromophenylmercapturic acid, whereas acid dehydration of 3,2-premercapturic acid gave both o- and m-bromophenylmercapturic acids. This implies a shift of sulphur in acid dehydration of the 3,4- and 3,2- but not the 4,3-premercapturic acids. 4. Base dehydration of the 3,4- and 4,3-premercapturic acid mixture gave a mixture of p- and m-bromophenylmercapturic acids, whereas base dehydration of the 3,2-premercapturic acid gave only m-bromophenylmercapturic acid. This indicates these premercapturic acids dehydrate by direct elimination without rearrangment. 5. The 3,2-premercapturic acid was detected only in the urine of BNF-induced animals, whereas the 3,4- and 4,3-premercapturic acids were detected in the urines of untreated as well as PB- and BNF-induced animals. 6. Together with earlier reports of the isolation of the 2,3-dihydrodiol, the isolation of the 3,2-premercapturic acid as a urinary metabolite of bromobenzene implies that bromobenzene-2,3-oxide is a discrete metabolite of bromobenzene and not merely a hypothetical intermediate.

Tensile regulation of axonal elongation and initiation

Neurites of chick sensory neurons in culture were attached by their growth cones to glass needles of known compliance and were subjected to increasing tensions as steps of constant force; each step lasted 30-60 min and was 25-50 mu dyn greater than the previous step. After correcting for elastic stretching, neurite elongation rate increased in proportion to tension magnitude greater than a tension threshold. The value of the tension threshold required for growth varied between 25 and 560 mu dyn, with most between 50 and 150 mu dyn. The growth sensitivity of neurites to tension was surprisingly high: an increase in tension of 1 mu dyn increased the elongation rate an average of about 1.5 microns/hr. The linear relationship between growth rate and tension provides a simple control mechanism for axons to accommodate tissue expansion in growing animals that consistently maintains a moderate rest tension on axons. Styrene microspheres treated with polyethyleneimine were used to label the surface of neurites in order to determine the site and pattern of surface addition during the experimental "towed growth" regime. New membrane is added interstitially throughout the neurite, but different regions of neurite vary widely in the amount of new membrane added. This contrasts with membrane addition specifically at the distal end in growth-cone-mediated growth. The different sites for membrane addition in growth mediated by towing and by the growth cone indicate that the membrane addition process is sensitive to the mode of growth. We confirmed the finding of Bray (1984) that neurites can be initiated de novo by application of tension to the cell margin of chick sensory neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

A knowledge-based experimental design system for nucleic acid engineering

Presented in this paper is a knowledge-based experimental design system that incorporates the domain expertise used in nucleic acid engineering, thus automating the processing of error-prone, laborious low-level work, and many decision-making steps, and guiding the biologist toward a workable plan. This allows the biologist to work at a higher abstraction level, concentrating on more fundamental, difficult and challenging problems directly related to protein structure - function relationships. Cassette-based site-directed mutagenesis and synthetic gene designs are used as examples to illustrate the utility of the knowledge-based system approach to experimental design.

Molecular properties of pyruvate bound to lactate dehydrogenase: a Raman spectroscopic study

Lactate dehydrogenase (LDH; EC 1.1.1.27) catalyzes the addition of pyruvate to the four position of the nicotinamide ring of bound NAD+; this NAD-pyruvate adduct is bound tightly to the enzyme. We have used the adduct as a model for pyruvate in a competent ternary complex by comparing the Raman spectrum of the bound adduct with that for unliganded pyruvate. To understand the observed normal modes of pyruvate both as the bound adduct and in water, we have taken the Raman spectra of a series of 13C- and 18O-labeled pyruvates. We find that the carboxylate COO- moiety of pyruvate remains unprotonated at LDH's active site and forms an ion pair complex. The frequency of pyruvate's carbonyl C = O moiety shifts from 1710 cm-1 in water downward 34 cm-1 when pyruvate binds to LDH. This frequency shift corresponds to a ca. 34% polarization of the carbonyl bond, indicates a substantial interaction between the C = O group and enzyme, and is direct evidence for and is a measure of enzyme-induced electronic perturbation of the substrate needed for catalysis. This bond polarization is likely brought about by electrostatic interactions between the carbonyl moiety and the protonated imidazole group of His-195 and the guanidino group from Arg-109. We discuss how the data bear on the enzymatic chemistry of LDH.

Classical Raman spectroscopic studies of NADH and NAD+ bound to lactate dehydrogenase by difference techniques

The binding of the coenzymes NAD+ and NADH to lactate dehydrogenase causes significant changes in the Raman spectra of both of these molecules relative to spectra obtained in the absence of enzyme. The molecular motions of the bound adenine moiety of both NAD+ and NADH as well as adenine containing analogues of these coenzymes produce Raman bands that are essentially identical, suggesting that the binding of adenine to the enzyme is the same regardless of the nicotinamide head-group nature. We also have observed that the molecular motions of the bound adenine moiety are different from both those obtained when it is in either water, various hydrophobic solvents, or various other solvent compositions. Protonation of the bound adenine ring at the 3-position is offered as a possible explanation. Significant shifts are observed in both the stretching frequency of the carboxamide carbonyl of NAD+ and the rocking motion of the carboxamide NH2 group of NADH. These shifts are probably caused by hydrogen bonding with the enzyme. The interaction energies of these hydrogen-bonding patterns are discussed. The aromatic nature of the nicotinamide moiety of NAD+ appears to be unchanged upon binding. Pronounced changes in the Raman spectrum of the nicotinamide moiety of NADH are observed upon binding; some of these changes are understood and discussed. Finally, these results are compared to analogous results that were recently reported for liver alcohol dehydrogenase [Chen et al. (1987) Biochemistry 26, 4776-4784]. In general, the coenzyme binding properties are found to be quite similar, but not identical, for the two enzymes.

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.

A knowledge-based system for cassette mutagenesis experimental design

A knowledge-based system for the design and planning of cassette mutagenesis experiments has been developed for scientists working in the field of structural biology and protein engineering. The system applies domain-specific knowledge to manage the menial details and automate most of the decision-making steps involved in the design process. This allows scientists to work at a high abstraction level, and results in significant time savings and increased productivity. The system also includes an automated documentation facility to improve the efficiency and accuracy of record keeping.

[In vivo metastasis of human tumor transplant in T and NK cell immune-deficient mice]

Beige-nude mice with combined T and NK cell deficiency were produced by introducing "nu" gene into the beige mice of C57BL/6 background. The beige-nude mice were characterized by morphological features, level and activity of the NK cell in spleen and peripheral blood. NK cell level of the beige-nude mice was higher than the beige mice and similar to the ordinary nude mice though its NK cell activity was markedly lower than the nude mice. Human lung adenocarcinoma (PAa) was transplanted subcutaneously to the beige-nude mice and nude mice of BALB/cA background. No metastasis was found in BALB/cA nude mice (0/7), while in beige-nude mice, spontaneous lymph node metastasis rate was 36.3% (4/11). It should be noted that the transplanted PAa metastasized to lungs, which had never been seen in BALB/cA nude mice in previous experiments. The increase of metastatic rate is correlated with the relative low NK cell activity of the beige-nude mice. Our observation is that the beige-nude mice could be a suitable experimental model for in vivo study on metastatic behavior of the human tumors.

Studies on the constituents of Artemisia annua Part II

The present paper is a continuation of our study on the Chinese traditional herb Artemisia annua L. [1-5], describing several additional constituents: quinghaosu IV and V (V, VII), quinghao acid (VIII) [6], chrysosplenol (VIa) [7] and a paraffinic alcohol; V, VII and VIII are compounds with unreported structures.