Butanol extracts from myelin fragments. III. SDS-urea gel electrophoretic studies

Serotonin binding sites. II. Muramyl dipeptide binds to serotonin binding sites on myelin basic protein, LHRH, and MSH-ACTH 4-10

Previously, we reported the existence of structurally similar serotonin binding sites on myelin basic protein, LHRH, and MSH-ACTH 4-10. We now report that the adjuvant peptide, muramyl dipeptide (N-acetyl-muramyl-L-Ala-D-isoGln) also binds to these sites. This observation may help to explain previous observations of serotonin-like activity by muramyl peptides, including the promotion of slow-wave sleep and fever induction. The observation may also provide an important link between the immune system and the nervous system that may explain the role of muramyl dipeptide adjuvants in causing autoimmune diseases to serotonin-regulated proteins and their receptors, as well as the alterations in serotonin levels that are often observed in autoimmune diseases. The observation provides concrete evidence for a dual-antigen hypothesis for the induction of autoimmune diseases by an adjuvant-peptide complex. Application of such a mechanism for induction of autoimmunity may be of importance in understanding a number of postinfectious and postvaccinal neuropathies, and suggests a possible etiology for autism, in which many patients have high blood serotonin levels, autoimmune reactions to myelin basic protein, and antibodies to serotonin binding sites. Finally, the observation suggests that glycopeptides may act as neurotransmitters.

Serotonin binding sites. I. Structures of sites on myelin basic protein, LHRH, MSH, ACTH, interferon, serum albumin, ovalbumin and red pigment concentrating hormone

We report the results of nuclear magnetic resonance spectroscopy studies of combinations of serotonin (5-hydroxytryptamine) with the tryptophan peptide sequence and similar peptides from myelin basic protein. The binding site appears to consist of the sequence Arg Phe Ser Trp. Similar serotonin binding sites were found to exist on LHRH (Tyr Ser Trp) and MSH-ACTH tetrapeptide (Phe Arg Trp). These binding sites are specific to serotonin as is demonstrated by lack of binding by dopamine, histamine, acetylcholine and a dozen other pharmacologically active amines and indoles. Drugs known to affect serotonin levels, e.g., fenfluramine and L-DOPA, bind weakly to these sites. Structural and functional similarities between the tryptophan peptide, LHRH, and MSH-ACTH with an ACTH-like peptide of human leukocyte interferon, with human and bovine serum albumin, hen ovalbumin, and with red pigment concentrating hormone suggest that the latter peptides may also contain similar serotonin binding sites. The elucidation of serotonin binding sites on these peptides and proteins has implications for understanding various aspects of cancer, autoimmunity, neurological disease, and peptide hormone control.

Chemical and biological properties of Lipopolysaccharides from symbiotic luminous bacteria from several luminous marine animals

The chemical and biological properties of lipopolysaccharides (LPS) in five strains of symbiotic luminous bacteria isolated from four species of luminous marine fishes, Coelorhynchus kishinouyei (CK-1), Chlorophthalmus albatrossis (CA-1), Ventrifossa garmani (VG-1), and Acropoma japonicum (AJ-1b), as well as from a luminous squid, Doryteuthis kensaki (DK-1) were examined. The LPS isolated from these symbiotic luminous bacteria were characterized by the absence of 2-keto-3-deoxyoctonate, known to be a basic component of the usual gram-negative bacterial LPS. All LPS from these symbiotic luminous bacteria upon electrophoresis in sodium dodecylsulfate polyacrylamide gel exhibited one or two clear main bands with high mobility, and one or two obscure minor bands with low mobility when stained with periodate-Schiff reagent. LPS from CA-1 and VG-1 exhibited similar electrophoretic patterns, whereas the electrophoretic patterns of the LPS from CK-1, AJ-1b, and DK-1 were easily distinguishable from each other. All these LPS also had similarly potent and diverse biological activities in regard to their adjuvanticity, immunosuppression, polyclonal effect, B-cell mitogenicity, and activation of the phagocytic function of macrophages.

Butanol extracts from myelin fragments: identification of 5-hydroxytryptamine binding components

To investigate the nature of 5-HT binding components originated from myelin butanol extracts (i.e. proteolipids), the recombinate experiments with acidic lipids were planned. Binding assay of 14C . 5-Ht to recombinates was carried out by Sephadex lh20 column chromatography. Among several recombinate fractions, recombinate of sulphatides, phosphatidylserine and phosphatidylinositol showed the same elution profile and binding capacity for 14C . 5-HT with those of the myelin extracts. The displacement studies with other neurotransmitters revealed that the recombinate of these three acidic lipids completely regenerated the specificity of the original myelin proteolipids. Namely, tryptamine, DA and ACh inhibited the 5-HT binding but NA had no effect. A double reciprocal plot of 5-HT binding represented a multiple binding mode, not a straight line. This observation suggested that, at least, three binding components (or sites) are implicated in the binding of 14C . 5-HT to this recombinate system having 3 Kds of 2.2 x 10(-7), 4.1 x 10(-7) and 4.2 x 10(-6) m. All these observations infer that the 5-HT binding components of myelin proteolipids are mainly three acidic lipids in nature.

Chemical and biological properties of lipopolysaccharide from a marine bacterium, Photobacterium phosphoreum PJ-1

The chemical and biological properties of the lipopolysaccharide (LPS) isolated from a marine bacterium, Photobacterium phosphoreum PJ-1, were studied. This LPS consists of 40.6% carbohydrate, 27.3% fatty acid, 0.2% 2-keto-3-deoxyoctonate (KDO) and other components. One characteristic of this LPS is its small amount of KDO, the basic component of the usual LPS. Electrophoresis in sodium dodecylsulfate polyacrylamide gel revealed at least two staining bands for carbohydrates. These bands were continuous and broad, and showed rapid electrophoretic mobility which corresponded closely to the fastest moving band of LPS from Salmonella typhimurium. This LPS preparation had adjuvant activity, lethality for ddY mice, and the ability to gel Limulus amebocyte lysate, and the strength of these activities corresponded closely to those of LPS preparations from Escherichia coli 0111:B4 and S. typhimurium. In the test for lethality of the LPS for ddY mice, the lethal action appeared in two phases depending on the dose used for intravenous (i.v.) injection: the early lethal action appeared within 30 min after injection of 250 micrograms or less, and the late lethal action occurred gradually after 16 hr at doses of 500 microgrms or more. The total (both phases) LD50 of this LPS (i.v.) for ddY mice was 265 micrograms per mouse and in only the late phase it was 500 micrograms. These results show that in spite of structural differences in regard to KDO content, LPS from P. phosphoreum PJ-1 has some biological properties similar to those of LPS from E. coli 0111:B4 and S. typhimurium but it shows no immunological cross-reaction with other LPS.