Theodore Chase

The effect of elastase-specific monoclonal and polyclonal antibodies on the virulence of Aspergillus fumigatus in immunocompromised mice.

Elastase has been implicated as a potential virulence factor involved in the invasion process of the opportunistic pathogen,Aspergillus fumigatus. Monoclonal and polyclonal antibodies, known to inhibit elastase in vitro, were employed in an immunocompromised mouse model of invasive aspergillosis to determine if the antibodies could protect mice from fatal infection. Individual monoclonal antibodies, known to inhibit elastase partially (13 to 23%), or combinations of monoclonal antibodies, known to inhibit elastase 70 to 100%, were tested in the mouse model. No individual nor combination of monoclonal antibodies protected immunosuppressed, infected mice in the doses tested. Similarly, elastase-specific polyclonal antibodies, raised in mice or rabbits, did not exhibit a protective effect, nor did immunization of mice with elastase prior to immunosuppression and infection. Histological examination of the lungs of immunosuppressed, infected mice showed no amelioration of fungal invasiveness by treatment with elastase-specific monoclonal or polyclonal antibodies. However, immunocompetent mice, instilled with a spore inoculum much higher than used in the preceding studies and treated with antibodies, survived, while control mice not treated with antibodies were overwhelmed by the massive spore dose and died. Nevertheless, overall evidence suggests that elastase may not be the primary virulence factor involved in invasive pulmonary aspergillosis.

Chemical Modification of Mushroom Tyrosinase for Stabilization to Reaction Inactivation

The utilization of chemical modification to evoke or favor a particular response while avoiding an undesirable characteristic of the protein is nothing new. Formaldehyde has been used to modify bacterial toxins, rendering them incapable of eliciting a toxic response, but still able to produce an immunological response when injected into an animal. The ancient process of tanning has been improved by the use of glutaraldehyde, a cross-linking agent. Insolubilization of enzymes for use in column or filtration techniques for the destruction or alteration of substances has received much recent attention. Hence, immobilization and subsequent modification of an enzyme, or immobilization of the modified enzyme, would seem to be a reasonable procedure.

Electrophoresis of the Proteins of the Nuclear Polyhedrosis Virus of Porthetria dispar

The nuclear polyhedrosis virus (NPV) of Porthetria dispar (gypsy moth) was isolated and purified in order to examine its protein components, which have been little studied in insect viruses. Virus par

Determination of protein immobilized on solid support by tryptophan content

Abstract The method of Gaitonde and Dovey [ Biochem. J. 117, 907 (1970)] for the determination of tryptophan by reaction with ninhydrin in acid is adapted for the measurement of protein bound to solid support materials, including collagen. DEAE-Sephadex, DEAE-cellulose, polyacrylamide and collodion give negligible background absorbance with the reagent; collagen and activated agarose give some color, but this can be abolished by pretreating the collagen with H 2 O 2 . Collagen, Sephadex and agarose dissolve in the reagent. Levels of lactase (β-galactosidase) and glucoamylase were readily and linearly measured down to 0.2 mg in the presence of 21 mg collagen, and activity and immobilized protein content of lactase-collagen complexes were linearly related.

Non-coding nucleotides and amino acids near the active site regulate peptide deformylase expression and inhibitor susceptibility in Chlamydia trachomatis

Chlamydia trachomatis, an obligate intracellular bacterium, is a highly prevalent human pathogen. Hydroxamic-acid-based matrix metalloprotease inhibitors can effectively inhibit the pathogen both in vitro and in vivo, and have exhibited therapeutic potential. Here, we provide genome sequencing data indicating that peptide deformylase (PDF) is the sole target of the inhibitors in this organism. We further report molecular mechanisms that control chlamydial PDF (cPDF) expression and inhibition efficiency. In particular, we identify the σ66-dependent promoter that controls cPDF gene expression and demonstrate that point mutations in this promoter lead to resistance by increasing cPDF transcription. Furthermore, we show that substitution of two amino acids near the active site of the enzyme alters enzyme kinetics and protein stability.

Subunit structure and kinetic properties of l-β-hydroxyacid dehydrogenase of Drosophila

Abstract l -β-hydroxyacid dehydrogenase ( l -glutonate:NAD+ 3-oxidoreductase, EC 1.1.1.45) of Drosophila is made up of two non-identical subunits with molecular weights of 40 000 and 23 500. Michaelis constants calculated at saturating concentrations of th other substrate were 0.13 mM for NAD+, .85 mM for l -gulonate, 14.8 mM for l -β-hydroxybutyrate; dissociation constants ( K ia ) were 2.8 mM for l -gluonate, 22 mM for l -β-hydroxybutyrate. The maximum velocity with l -gluonate as substrate was ten-fold greater than with β-hydroxybutyrate. As product inhibitors, both NADH and acetoacetate are competitive vs. both substrates, suggesting a rapid equilibrium random mechanism.

Inhibition ofZymomonas growth by carbon sources

SummaryZymomonas mobilis growth is slowed by 250g substrate/L. The effect is less marked in media containing 20g substrate/L and 230g non-fermentable sugar/L. This suggests that high sugar media exert more than a simple osmotic effect.

Chemical characterization studies of the nuclear polyhedrosis virus of Porthetria dispar

Abstract The nuclear polyhedrosis virus (NPV) of Porthetria dispar was isolated and purified through a two-step zonal centrifugation procedure. The LD50 of the purified NPV was determined by a dose-response assay. Quantitative analyses were made of whole polyhedra and of separated fractions of polyhedral protein, virus rods, and denatured material, i.e., the pellet obtained from low speed centrifugation of dissolved polyhedra, to determine the protein, DNA, and “RNA” (orcinol-positive material) present in this NPV. Approximately one-half the “RNA” was present in the denatured material. Trace elements were also determined, and four, Fe, Mg, Cu, and Zn, of the ten assayed were present in the polyhedral protein fraction, while only Mg and Zn were in the virus rod fraction.