Cross reactive antigens of Acholeplasma laidlawii and L-form of Staphylococcus aureus]

We demonstrated that the membrane of Acholeplasma laidlawii PG8 and L-form of Staphylococcus aureus, both of which induce cellular immunity in BALB/c mice, were antigenically related each other. Foodpad responses of the mice immunized with a mixture of either antigen and Freund's complete adjuvant showed clearly a cross reaction when challenged with the other antigen. Cross responses to incorporate 3H-thymidine to the spleen lymphocytes of the mice immunized with either antigen occurred in the presence of the other antigen. Furthermore, the purified T cells, but not B cells, of the spleen were activated in the presence of antigen-presenting cells. These antigens existing in the membrane fractions of both microorganisms were purified by Razin's method. Finally, these membrane components of A. laidlawii and L-form of S. aureus were subjected to gel electrophoresis and transferring to nitrocellulose membrane and used to stimulate the spleen lymphocytes of the mice immunized with A. laidlawii or of non-immunized mice. The fractions representing molecular weights of approximately 45 kD, 25 kD, and 13 kD of both microorganisms consistently stimulated the lymphocytes of the immunized mice but not those of non-immunized mice.     

Structure-activity relationships in human interleukin-1 alpha: identification of key residues for expression of biological activities.

To identify the sites important for the different biological activities of human interleukin-1 alpha (hIL-1 alpha), 56 single-amino acid-substituted mutants of hIL-1 alpha were produced in Escherichia coli using site-directed mutagenesis, and were examined for their biological activities such as mouse lymphocyte activating factor activity (LAF activity), cytostatic activity against human melanoma cells A-375 (A375 activity) and prostaglandin E2 (PGE2) inducing activity in human osteosarcoma cells MG-63 (PEI activity). Two amino acid residues, Asp26 and Asp151, were found to be important for these activities. The replacement of Asp26 by Val caused a decrease in LAF and PEI activities by one or two orders of magnitude and a slight decrease in A375 activity. The Tyr or Phe substitution for Asp151 caused decreases in LAF and A375 activities by one or two orders of magnitude and complete loss of PEI activity. The change from Asp151 to Lys or Arg resulted in marked decrease in LAF activity and complete loss of A375 and PEI activities. Since Asp26 and Asp151 are close to each other in the three-dimensional structure, the region involving these amino acids seems to be important for the biological activities of hIL-1 alpha.     

A new model of counterion condensation in polyelectrolyte solutions. III. Theoretical predictions of competitive condensation between counterions of different valences

Our model has been extended for theoretical estimation of competitive condensation of counterions of different valences onto polyelectrolytes in solution. The estimations are compared with those obtained from Manning theory and with experimental data on counterion activity coefficients. The agreement with the data for sodium polystyrenesulfonate/MgCl2, CaCl2 is satisfactory.     

Preparation and characterization of human interleukin-5 expressed in recombinant Escherichia coli.

The gene coding for human interleukin-5 was synthesized and expressed in Escherichia coli under control of a heat-inducible promoter. High-level expression, 10-15% of total cellular protein, was achieved in E. coli. The protein was produced in an insoluble state. A simple extraction, renaturation and purification scheme is described. The recombinant protein was found to be a homodimer, similar to the natural murine-derived protein. Despite the lack of glycosylation, high specific activities were obtained in three 'in vitro' biological assays. Physical characterization of the protein showed it to be mostly alpha-helical, supporting the hypothesis that a conformational similarity exists among certain cytokines.     

Biosynthesis of thyrotropin releasing hormone in the skin of Xenopus laevis: partial sequence of the precursor deduced from cloned cDNA

Skin of Xenopus laevis contains relatively large quantities of thyrotropin releasing hormone (TRH). Total mRNA isolated from skin was cloned in the plasmid pUC8. Among 1400 cDNA clones, one was found with an insert of 478 nucleotides coding for the amino-terminal part of prepro-TRH. This clone was detected using a mixture of two synthetic undecanucleotides for colony hybridization. The single open reading frame starts with a methionine residue and a stretch of hydrophobic amino acids, as is typical for signal peptides, and terminates at the poly(C) tail without a stop codon. The deduced polypeptide of 123 amino acids contains three copies of the sequences Lys-Arg-Gln-His-Pro-Gly-Lys Arg-Arg and a fourth incomplete copy at the carboxyl end. Typical pro-hormone processing at this sequence would yield pGlu-His-Pro.NH2,i.e. TRH. It is concluded that the cloned part of the mRNA codes for prepro-TRH and that the TRH precursor from skin of X. laevis is a polyprotein containing at least four copies of the end product in its amino acid sequence.     

Reciprocal translocation between the long arms of chromosomes four and six of Paragonimus westermani from the Philippines.

C-banding patterns have been observed in 14 specimens of Paragonimus westermani from Jaro, Leyte, the Philippines. One of them showed mutations of 2 chromosomes in spreads. Comparative analysis of C-banding patterns between the individual and standard type clarified that the mutant resulted from a reciprocal translocation between the long arms of chromosomes 4 and 6.     

Effects of Dietary Amino Acids on Brain Amino Acids and Transmitter Amines in Rats with a Portacaval Shunt

The etiologic relationship between disturbances in metabolism of amino acids and amines and hepatic coma was investigated by examining the effects of diets containing various mixtures of amino acids on brain amine metabolism in rats with a portacaval shunt, using a method for simultaneous analysis of amino acids and amines. Rats with a portacaval shunt were fed on four different amino acid compositions with increased amounts of various amino acids suspected to be etiologically related to hepatic coma, such as methionine, phenylalanine, tyrosine, and tryptophan. The animals were killed 4 weeks after operation. During the experimental period, these animals did not become comatose, but exhibited various behavioral abnormalities. Marked increase in the plasma and brain levels of the augmented amino acids, especially methionine and tyrosine, were observed in rats with a portacaval shunt. Brain noradrenaline, dopamine, and serotonin levels were significantly decreased when the brain tyrosine level was increased. These results indicate that in rats with a portacaval shunt the dietary levels of amino acids greatly influence the brain levels of both amino acids and transmitter amines.     

Substrate binding characteristics of the active site of spermidine dehydrogenase from Serratia marcescens.

The substrate specificity of spermidine dehydrogenase from Serratia marcescens was studied using many kinds of naturally occurring and synthetic polyamines. Diamines inhibited the enzyme competitively and their inhibitor constants tended to decrease with increasing methylene chain length in the diamines. All of the triamines and tetramines examined were active as substrates, and the amines containing a 4-aminobutylimino moiety (NH2(CH2)4NH-) in their structures were more active. N-Alkylputrescine was also oxidized by the enzyme. All of the amines containing a 4-aminobutylimino group were oxidized to form 1-pyrroline stoichiometrically as one of the products. Tetramines containing a 3-aminopropylimino group (NH2(CH2)3NH-) were oxidized to form 1,3-diaminopropane. However, in the case of an amine containing both 4-aminobutylimino and 3-aminopropylimino groups, the imino moiety of the former was preferentially oxidized by the enzyme. On the basis of the substrate specificity, the binding characteristics of the enzyme are discussed and a subsite model for the binding site is proposed.