Acetone Precipitation—An Improved Procedure for the Isolation of Soybean Agglutinin

Isolation of soybean agglutinin (SBA) by the salt fractionation involves excessive amounts of (NH₄) ₂ SO ₄. We have found that SBA could be fractionally precipitated from an aqueous extract by adding acetone (40% final concentration). It is stable under these conditions for minimum 2 h at 5°C and 25°C. Incorporating these results, an improved procedure for the isolation of SBA has been developed. The SBA isolated by this method is obtained in better yield, has 6000 HU/mg protein and is identical to that isolated by the (NH₄)₂ SO ₄ method as ascertained by chromatographic and electro-phoretic comparisons and hapten inhibition assays.     

The Regulatory Role of Reticulons in Neurodegeneration: Insights Underpinning Therapeutic Potential for Neurodegenerative Diseases

Cellular and Molecular Neurobiology - In the last few decades, cytoplasmic organellar dysfunction, such as that of the endoplasmic reticulum (ER), has created a new area of research interest...     

Microbial β-Glucosidases: Cloning,Properties, and Applications

ABSTRACT:?

β-Glucosidases constitute a major group among glycosylhydrolase enzymes. Out of the 82 families classified under glycosylhydrolase category, these belong to family 1 and family 3 and catalyze the selective cleavage of glucosidic bonds. This function is pivotal in many crucial biological pathways, such as degradation of structural and storage polysaccharides, cellular signaling, oncogenesis, host-pathogen interactions, as well as in a number of biotechnological applications. In recent years, interest in these enzymes has gained momentum owing to their biosynthetic abilities. The enzymes exhibit utility in syntheses of diverse oligosaccharides, glycoconjugates, alkyl- and amino-glucosides. Attempts are being made to understand the structure-function relationship of these versatile biocatalysts. Earlier reviews described the sources and properties of microbial β-glucosidases, yeast β-glucosidases, thermostable fungal β-glucosidase, and the physiological functions, characteristics, and catalytic action of native β-glucosidases from various plant, animal, and microbial sources. Recent efforts have been directed towards molecular cloning, sequencing, mutagenesis, and crystallography of the enzymes. The aim of the present article is to describe the sources and properties of recombinant β-glucosidases, their classification schemes based on similarity at the structural and molecular levels, elucidation of structure-function relationships, directed evolution of existing enzymes toward enhanced thermostability, substrate range, biosynthetic properties, and applications.     

Purine metabolism in Mycobacterium leprae grown in armadillo liver

Abstract Mycobacterium leprae organisms generally incorporated purines more rapidly than pyrimidines into nucleic acids from the incubation medium. Purine synthesis de novo took place at a very slow rate suggesting a preference of the organism for preformed purines. In cell-free extracts of leprosy bacilli, enzyme for scavenging and interconversion of purines were detected. The results are discussed in the light of the failure to cultivate M. leprae in vitro, and the use of labelled substrates to determine the viability of suspensions of leprosy bacilli and their sensitivity to anti-leprosy drugs.     

Activation of potassium-dependent H+ efflux from mitochondria by cadmium and phenylarsine oxide

Addition of Cd²⁺ or phenylarsine oxide (PhAsO) to respiring rat liver mitochondria results first in acidification of the medium (H⁺ efflux) followed by disappearance of H⁺ (discharge of the pH gradient or uncoupling). The first phase of H⁺ efflux is dependent upon the presence of K⁺ in the medium, and is not seen in the presence of valinomycin, which is consistent with the conclusion that H⁺ efflux is linked to membrane potential-dependent uptake of K⁺. These effects are abolished by low levels of 2,3-dimercaptopropanol but potentiated by excess of 2-mercaptoethanol, showing involvement of a dithiol type of group in the response. Mersalyl produces only the H⁺ efflux, and subsequent addition of Cd²⁺ or PhAsO produces collapse of the pH.Abbreviations BAL British Anti-Lewisite or 2,3-dimercaptopropanol - 2-ME 2-mercaptoethanol - PhAsO phenylarsine oxide - FCCP carbonylcyanide trifluoromethoxyphenylhydrazone - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid     

Plant growth regulatory metabolites from novel actinomycetes

Metabolites from 796 isolates of aerobic actinomycetes were screened for plant growth regulatory properties using an algal bioassay. These included 266 isolates ofStreptomyces, 28 unidentified actinomycetes, and 502 isolates of novel actinomycetes represented by 18 genera. Algal growth inhibition of 30% was observed with 60 isolates, 37 of which belonged to the genusStreptomyces. Among other inhibitors were 8 isolates ofActinomadura, 6 ofActinoplanes, 2 each of the generaThermomonospora, Streptoverticillium, andPromicromonospora, and 3 unidentified. Metabolites from 70 isolates promoted algal growth by 20%. These included 13 isolates ofMicromonospora, 11 ofStreptomyces, 6 ofNocardia, 5 ofActinomadura, and 4 each ofRhodococcus andThermomonospora. Sixteen unidentified isolates; 3 isolates ofPromicromonospora; 2 isolates each ofActinoplanes, Streptosporangium, andOerskovia; and 1 of Thermoactinomyces peptonophilus-like organism andSaccharomonospora viridis also promoted the algal growth by 20%. The plant growth inhibitory properties of 9 actinomycetes and the growth promoting properties of 6 were demonstrable during the secondary screening on higher plants using chemicals extracted from the culture broth. The metabolites fromMicromonospora, Nocardia, Rhodococcus, Streptosporangium, andOerskovia isolates were associated with plant growth promotion only; those fromStreptomyces were most frequently involved with the growth inhibition.This is Michigan Agriculture Experiment Station Journal Article No. 12191.     

The effect of pH and organic ester penetration enhancers on skin permeation kinetics of terbutaline sulfate from pseudolatex-type transdermal delivery systems through mouse and human cadaver skins

The purpose of this research was to prepare a pseudolatex transdermal delivery system for terbutaline sulfate and to evaluate the effect of pH and organic ester penetration enhancers on permeation kinetics of terbutaline sulfate through mice abdominal skin and human cadaver skin. An increase in the permeation flux by increasing pH was observed. The distribution coefficient of terbutaline sulfate between 1-octanol and buffers of different pH values was also pH-dependent. Furthermore, the change of the permeability coefficient with pH correlated well with the distribution coefficient by a 2-degree polynomial equation. The permeation profile and related kinetic parameters of terbutaline sulfate was determined in presence of 3 estertype permeation enhancers incorporated in the films, viz methyl laureate, isopropyl lanolate, and isopropyl myristate. Among the 3, the more pronounced enhancing effect was obtained with isopropyl myristate, regarding the permeatin flux, permeability coefficient, and diffusion coefficient. This was attributed to solubility parameter of isopropyl myristate being closer to the solubility parameter of human skin, and such a pronounced enhancing effect was probably caused by its passage across the skin barrier through the lipid pathway. Published: September 30, 2005     

The needle component of the type III secreton of Shigella regulates the activity of the secretion apparatus

Gram-negative bacteria commonly interact with eukaryotic host cells by using type III secretion systems (TTSSs or secretons). TTSSs serve to transfer bacterial proteins into host cells. Two translocators, IpaB and IpaC, are first inserted with the aid of IpaD by Shigella into the host cell membrane. Then at least two supplementary effectors of cell invasion, IpaA and IpgD, are transferred into the host cytoplasm. How TTSSs are induced to secrete is unknown, but their activation appears to require direct contact of the external distal tip of the apparatus with the host cell. The extracellular domain of the TTSS is a hollow needle protruding 60 nm beyond the bacterial surface. The monomeric unit of the Shigella flexneri needle, MxiH, forms a superhelical assembly. To probe the role of the needle in the activation of the TTSS for secretion, we examined the structure-function relationship of MxiH by mutagenesis. Most point mutations led to normal needle assembly, but some led to polymerization or possible length control defects. In other mutants, secretion was constitutively turned "on." In a further set, it was "constitutively on" but experimentally "uninducible." Finally, upon induction of secretion, some mutants released only the translocators and not the effectors. Most types of mutants were defective in interactions with host cells. Together, these data indicate that the needle directly controls the activity of the TTSS and suggest that it may be used to "sense" host cells.