The relationship between biological activity and primary structure of troponin I from white skeletal muscle of the rabbit.

1. A series of defined peptides which span the complete sequence were produced from troponin I isolated from white skeletal muscle of the rabbit. 2. Two peptides, CF1 (residues 64-133) and CN4 (residues 96-117) inhibited the Mg2+-stimulated adenosine triphosphatase of desensitized actomyosin. This inhibition was potentiated by tropomyosin and the Mg2+-stimulated adenosine triphosphatase of desensitized actomyosin. This inhibition, unlike that of troponin I and peptides derived from it, was not potentiated by tropomyosin. 4. The most active inhibitor, peptide CN4, was 45-75% as effective as troponin I when compared on a molar basis. The inhibitory peptide, CN4, and also whole troponin I were shown by affinity chromatography to interact specifically with actin. 5. A strong interaction with troponin C was demonstrated with peptide CF2 (residues 1-47), from the N-terminal region of troponin I. Somewhat weaker interactions were shown with peptides CN5 (residues 1-21) and with the inhibitory peptide CN4. 6. The significance of these interactions for the mechanisms of action of troponin I is discussed.     

Studies of polysaccharide fractions from the lipopolysaccharide of Pseudomonas aeruginosa N.C.T.C. 1999.

Two polymeric water-soluble fractions were isolated by gel filtration after mild acid hydrolysis of the lipopolysaccharide from Pseudomonas aeruginosa N.C.T.C. 1999. The fraction of higher molecular weight retained the O-antigenic specificity of the lipopolysaccharide and may be 'side-chain' material. This fraction was rich in N (about 10%) and gave several basic amino compounds on acid hydrolysis; fucosamine (at least 2.8% w/w) was the only specifc component identified. The fraction of lower molecular weight was a phosphorylated polysaccharide apparently corresponding to 'core' material. The major components of this fraction and their approximate molar proportions were: glucose (3-4); rhamnose (1); heptose (2); 3-deoxy-2-octulonic acid (1); galactosamine (1); alanine (1-1.5); phosphorus (6-7). In the intact lipopolysaccharide this fraction was probably linked to lipid A via a second residue of 3-deoxy-2-octulonic acid, and probably also contained additional phosphate residues and ethanolamine. The residues of 3-deoxy-2-octulonic acid were apparently substituted in the C-4 or C-5 position, and the phosphorylated heptose residues in the C-3 position. The rhamnose was mainly 2-substituted, though a little 3-substitution was detected. The glucose residues were either unsubstituted or 6-substituted. Four neutral oligosaccharides were produced by partial acid hydrolysis and were characterized by chemical, enzymic, chromatographic and mass-spectrometric methods of analysis. The structures assigned were: Glcpalpha1-6Glc; Glcpbeta1-2Rha; Rhapalpha1-6Glc; Glcpbeta1-2Rhapalpha1-6Glc. The galactosamine was substituted in the C-3 or C-4 position, the attachment of alanine was indicated, and evidence that the amino sugar linked the glucose-rhamnose region to the 'inner core' was obtained.     

Specific inhibitors of methane oxidation in Methylosinus trichosporium

Methane oxidation by washed cell suspensions of Methylosinus trichosporium OB3B was selectively inhibited by 25 compounds, including metal binding components such as carbon monoxide (85% O₂: 15% CO), KCN (10^-6 M), αα′-dipyridyl (10^-4 M), 8-quinolinol (10^-4 M), thiosemicarbazide (10^-5 M), thiourea (10^-5 M), hydroxylamine (10^-4 M), histidine (10^-2 M), British Anti-Lewisite (5x10^-3 M), and miscellaneous known inhibitors of other oxygenases. A role for copper in the methane oxygenase system was suggested by the pattern of inhibition and relief of inhibition by added metal ions.     

Contact toxicity of some chemical and biological pesticides to several insect parasitoids and predators

Eight pesticides; methyl parathion, malathion (organo-phosphates), toxaphene (chlorinated hydrocarbon), carbaryl (carbamate), pyrethrin (plant derivative),Bacillus thuringiensis, nuclear polyhedrosis virus (Heliothis) (microbial insecticides), and 2,4-DB (postemergence herbicide) were evaluated at the minimum recommended field dose and reduced dosages for contact toxicity toBrachymeria intermedia (Hymenoptera: Chalcididae), Campoletis sonorensis (Hymenoptera: Ichneumonidae), Chelonus blackburni (Hymenoptera: Braconidae), Meteorus leviventris (Braconidae), Voria ruralis (Diptera: tachninidae), Chrysopa carnea (Neuroptera: Chrysopidae), andHippodamia convergens (Coleoptera: Coccinellidae). At minimum field dosages, percent mortality of parasitoids and predators was>27%, for the chemical insecticides. Mortality from pyrethrin was <31%, in all cases and 0% for 5 of the 8 species tested. Mortality of parasitoids and predators exposed toB. thuringiens is and NPV was<4% while mortality from 2,4-DB was<7%. The toxicity of chemical insecticides to parasitoids and predators at reduced dosages in increasing order of toxicity was malathion > carbaryl > toxaphene > methyl parathion.     

Fluorescent and photo-affinity enkephalin derivatives: preparation and interaction with opiate receptors.

The fluorescent and photo-affinity derivatives of enkephalin, Tyr-D-Ala-Gly-Phe-Leu-Lys-N^ε-Rhodamine (II) and Tyr-D-Ala-Gly-Phe-Leu-Lys-N^ε-nitro-azidophenyl (III), were prepared by conventional methods followed by chemical modification. The two peptides inhibit the binding of ¹²⁵I-labeled enkephalin to brain membrane preparations, with apparent IC₅₀ values of 5.9 nM and 5.5 nM for peptides II and III, respectively. The iodinated derivative of peptide III binds specifically to brain membrane preparations with an apparent K_d of about 2.1 × 10^?9M.