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Biomedical subjects

A S Brecher

Publications and source records attributed to A S Brecher.

At least 37 records · Page 2Linked to original sources
PubMed1976

The hydrolysis of biologically active peptides by bovine lung tissue factor (thromboplastin).

Tissue factor apoprotein and relipidated tissue factor preparations extensively hydrolyze bradykinin, Lys-bradykinin, Met-Lys-bradykinin, substance P, [Asp1, Ile5]-angiotensin II, [Asp1, Ile5]-angiotensin I, and human fibrinopeptide A while acting more slowly on [Sar1, Ile5]-angiotensin II, [Me2Gly1, Ile5]-angiotensin II, bradykinin potentiating pentapeptide from B. jararaca, luteinizing hormone-releasing hormone, melanocyte stimulating hormone-release-inhibiting factor (Pro-Leu-Gly-NH2), and oxytocin. No hydrolysis of thyrotropin-releasing factor or bradykinin potentiating nonapeptide from B. jararaca is observed. Relipidated and apoprotein tissue factor act at identical rates under the conditions of the assay. Dansylation and chromatography of tissue factor-peptide incubation mixtures further indicate that relipidated and apoprotein tissue factor also hydrolyze peptides by identical mechanisms. No fewer than six bonds are hydrolyzed in bradykinin while the angiotensins and substance P are degraded to constituent amino acids. Only the N-terminal alanine is released from fibrinopeptide A. 2-Mercaptoethanol greatly inhibits the hydrolysis of bradykinin by relipidated tissue factor.

Angiotensin II↗
PubMed1975

Isolation and identification of alpha1-antitrypsin as a component of normal and malignant human breast and other tissues.

Alpha1-Antitrypsin has been detected using radial immunodiffusion in the 90,000g supernatant fraction of malignant and adjacent normal human breast, colon, and anal tissue, as well as malignant lung, stomach, and ileum. Immobilized chymotrypsin, bound to Sepharose or Affi-Gel 10 has been utilized to separate 11 peaks of antiproteolytic activity by affinity chromatography of normal and malignant human breast tissue extracts. Glycoproteins are associated with eight of the peaks. Peak 1 contains predominantly alpha1-antitrypsin in addition to a minor component. The purification of the inhibitors, as judged by disc gel electrophoresis, is extensive. In some peaks, only one or two protein bands are observed, suggesting that affinity chromatography on Sepharose- or Affi-Gel 10-chymotrypsin might be used for the isolation of alpha1-antitrypsin and other inhibitors in preparative amounts.

Anal Canal↗
PubMed1969

Brain arylamidase. Purfication and characterization of the soluble bovine enzyme.

1. An enzyme acting on aminoacyl-beta-naphthylamides has been isolated from the soluble fraction of bovine brain and purified 205-fold by means of ammonium sulphate fractionation, hydroxyapatite adsorption and DEAE-Sephadex column chromatography. 2. Arylamidase requires thiol groups for retention of its activity, is heat-labile and is susceptible to freezing. p-Chloromercuribenzoate and N-ethylmaleimide inactivate the enzyme rapidly. 3. Metal ions are not required for its activity, but stimulation by Mn(2+) and Mg(2+) and inactivation by Co(2+) and Zn(2+) are observed. 4. Optimum pH7.5 in phosphate buffer was exhibited for all substrates tested except l-leucyl-beta-naphthylamide, for which optimum pH is 6.5. 5. K(m) values for a number of substrates have been obtained and substrate inhibition at high concentrations was demonstrated. 6. The molecular weight is approx. 70000 as determined by Sephadex-gel filtration.

Aminopeptidases↗