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H L Asch

Publications and source records attributed to H L Asch.

4 recordsLinked to original sources
PubMed1979

Acidic thiol proteinase activity of Schistosoma mansoni egg extracts.

Extracts of the eggs of the human blood fluke, Schistosoma mansoni, exhibit proteolytic activity which requires the presence of added thiol reagents or cyanide. The pH optimum for hydrolysis of Azocoll and cartilage proteoglycan is 4.8--5.2 and the molecular weight of the major component is 25--26,000. The effects of inhibitors suggest this activity belongs to the acidic thiol proteinase class, with a similarity to Cathepsin B. These proteinases may be involved in nutrition of the egg or sporocyst, in penetration of eggs or miracidia through host tissues, or in the immunopathology of schistosomiasis.

Animals↗
PubMed1978

Effects of gentamicin on trypsin, chymotrypsin, and collagenase.

The effects of gentamicin on three proteolytic enzymes were studied. Gentamicin was tested at concentrations of 0.5-500 microgram/ml. Trypsin was tested at 0.5 microgram/ml using p-tosyl-L-arginine methyl ester and at 0.1 and 0.5 microgram/ml using azocoll as the substrate. Chymotrypsin was tested at 0.1 and 0.5 microgram/ml with azocoll. A soluble [14C]collagen assay was used to measure activity of collagenase derived from Clostridium histolyticum. The profiles of proteolytic activity vs. gentamicin concentration were similar for all three enzymes. At lower concentrations of gentamicin (less than 70 microgram/ml), there were two peaks of enhanced protease activity generally followed by inhibition. These unusual multiphasic effects of gentamicin on three different proteases are not presently understood, but they imply a previously unreported mode of action for this antibiotic.

Chymotrypsin↗
PubMed1977

Schistosoma mansoni: inhibition of cercarial "penetration" proteases by components of mammalian blood.

1. Normal human sera and plasma were fractionated in order to identify inhibitors of the "penetration" proteases of Schistosoma mansoni cercariae. 2. The main inhibitor, accounting for 90% of the total activity of serum, appears to be alpha 1-antitrypsin (alpha 1-AT) as identified by separation on DEAE-cellulose and Sephadex, by immunoelectrophoresis and by anticercarial protease activity of purified alpha 1-AT preparations. 3. The inhibition profiles of purified preparations of the 6 known serum antiproteases suggest that the parasite protease is similar to vertebrate chymotrypsin. 4. On a molar basis, the order of inhibitory activity against the cercarial protease is: alpha 1-AT = alpha 2-macroglobulin; C'-1-inactivator; alpha 1-antichymotrypsin. No inhibition was obtained with inter-alpha-inhibitor or antithrombin III.

Animals↗