Molecular mechanical studies of proflavine and acridine orange intercalation.

Previous workers have reported that proflavine and acridine orange form various structurally different complexes with the dinucleoside phosphates rCpG and dCpG, with uniform C3'-endo and mixed C3'-endo (3'-5') C2'-endo sugar puckers being observed. We present theoretical calculations, based on the method of molecular mechanics, which support the experimental observations. The results suggest that the mixed C3'-edo (3'-5') C2'-endo pucker conformation isi intrinsically more stable than the uniform C3'-endo conformation, but that the additional stabilisation gained from specific, hydrogen bonding, interactions between nucleic acid and solvent, or intramolecularly within the nucleic acid, can lead to the adoption of the latter conformation, or of variants between the two. The role played by hydrogen bonding between amino-groups and nucleic acid phosphate appears more subtle than previously supposed.     

Fermentation of swine waste-corn mixtures for animal feed: Pilot-plant studies

Summary Aerobic culture with solid substrates of fresh swine waste combined with corn resulted in lactic acid fermentation with odor control. Heterofermentative lactic acid bacteria produced lactic and homologous tatty acids from acetic through valeric acid (0.1 meq/dry g) to reduce pH 2 units to 4.2 to 4.6. During the fermentation, lactic acid organisms increased from 10⁷ to 10⁹/dry g. Coliform organisms remained steady in number at 10⁶ organisms/dry g. Pilot-plant scale fermentation produced a product with 21 to 39% more methionine than corn but was still limiting for this amino acid as well as lysine for young pigs. Fermentation product from fresh waste-corn cultures was fed as the major dietary component to young pigs, hens, and sheep. Pigs showed gain and gain/feed diminished by one-third in 13-day trials. Laying hens performed comparably to controls in a 21-day test, and sheep did not discriminate against fermentation product.     

Clonazepam and dopamine-related stereotyped behavior

The effect of clonazepam on behavioral stereotypy induced by a number of dopaminergic agonists was investigated. Clonazepam inhibited levodopa- and amphetamine-induced behavior in guinea pigs but did not alter lergotrile- or apomorphine-induced stereotypy. The results suggest that clonazepam influences the central dopaminergic system through a direct effect of dopaminergic presynaptic mechanisms.     

19F nuclear magnetic resonance studies of the coat protein of bacteriophage M13 in synthetic phospholipid vesicles and deoxycholate micelles.

The nonlytic, filamentous coliphage M13 offers an excellent model system for the study of membrane-protein interactions. We prepare derivatives of the protein containing fluorine-labeled amino acids and use 19F nuclear magnetic resonance (NMR) to study the protein in both deoxycholate micelles and phospholipid vesicles. We have previously described the in vivo preparation of an m-fluorotyrosyl derivative of M13 coat protein and also a method for incorporation of high levels of this protein into small, uniformly sized phospholipid vesicles of defined composition. Herein we describe the in vivo preparation and the characterization of an m-fluorophenylalanine derivative. We simultaneously compare the environment and mobility of the tyrosine and phenylalanine residues (the former in the hydrophobic region of the protein and the latter in the hydrophilic regions) as influenced by bile salt detergent or lipid interactions.     

Design of bioactive peptides based on antibody hypervariable region structures. Development of conformationally constrained and dimeric peptides with enhanced affinity

The variable regions of antibody molecules bind antigens with high affinity and specificity. This binding is imparted largely by the hypervariable portions of the variable region. Hypervariable regions typically fold into reverse turn or loop structures. Peptides derived from antibody hypervariable region sequences can bind antigens with similar specificity, albeit with markedly lower affinity. In this study, cyclic and dimeric peptide analogs of an anti-idiotypic/antireceptor antibody hypervariable region were developed. This antibody (87.92.6) binds to reovirus type 3 receptors on cells as well as to a neutralizing anti-reovirus type 3 monoclonal antibody (9B.G5). The cyclic peptides were utilized to probe the optimal conformation for binding to both the receptor and 9B.G5. By dimerizing or constraining the conformation of these peptides, higher affinity binding was produced. By utilizing several different cyclic peptides, the optimal conformation for binding was established. The conformationally optimized cyclic peptide possessed greater than 40-fold higher affinity for the receptor and the idiotype than the linear analog. This study suggests that conformationally constrained and dimeric peptides derived from antibody hypervariable loop sequences can bind antigens (including receptors) with reasonable affinity. hypervariable loop sequences can bind antigens (including     

Crystallization and preliminary X-ray investigation of bovine liver mitochondrial aldehyde dehydrogenase.

Aldehyde dehydrogenase from bovine liver mitochondria has been crystallized using the sitting drop method of vapor diffusion at 22 degrees C. The crystals formed from solutions containing, 40 mM-sodium citrate, 1 mM-NAD+ and 21% to 24% polyethylene glycol 3400 (pH 5.3 to 5.5). X-ray diffraction data collected from these crystals indicate that the crystals belong to the orthorhombic space group P2(1)2(1)2(1) with cell dimensions of a = 153.7 A, b = 159.37 A and c = 101.45 A. The crystals diffract to at least 2.9 A and a tetramer may comprise the asymmetric unit.     

Hepatitis C virus (HCV) circulates as a population of different but closely related genomes: quasispecies nature of HCV genome distribution.

Sequencing of multiple recombinant clones generated from polymerase chain reaction-amplified products demonstrated that the degree of heterogeneity of two well-conserved regions of the hepatitis C virus (HCV) genome within individual plasma samples from a single patient was consistent with a quasispecies structure of HCV genomic RNA. About half of circulating RNA molecules were identical, while the remaining consisted of a spectrum of mutants differing from each other in one to four nucleotides. Mutant sequence diversity ranged from silent mutations to appearance of in-frame stop codons and included both conservative and nonconservative amino acid substitutions. From the relative proportion of essentially defective sequences, we estimated that most circulating particles should contain defective genomes. These observations might have important implications in the physiopathology of HCV infection and underline the need for a population-based approach when one is analyzing HCV genomes.