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W J Schrenk

Publications and source records attributed to W J Schrenk.

7 recordsLinked to original sources
PubMed1982

Antithrombin BM from human plasma: an antithrombin binding moderately to heparin.

A human antithrombin was purified app. 60 fold from Cohn fraction IV, to give a single band of about 70.000 molecular weight in polyacrylamide gel electrophoresis. Compared to the similar antithrombin III, this glycoprotein binds only moderately to porcine heparin (hence its name Antithrombin BM), thus requiring higher heparin concentration for full thrombin inhibitor function, and lower ionic strength for elution from a heparin sepharose column. In these respects it resembles "heparin cofactor A", which is, however, characterized by a substantially larger molecular weight. From AT III, AT BM further differs in its absolute dependency on the presence of heparin(oids) for antithrombin activity, in its more pronounced inhibitory specificity largely restricted to thrombin, and in the absence of substantial immunological crossreaction with antibody to AT III. Based on comparative measurements of antithrombin activity in the presence of different amounts of heparin, up to 40% of the antithrombin activity present in human blood may be attributed to AT BM. The in vivo role of this new inhibitor remains to be elucidated.

Adult↗
PubMed1981

Expression in Escherichia coli of biologically active enzyme by a DNA sequence coding for the human plasminogen activator urokinase.

We have isolated clones of Escherichia coli strain K-12 that contain a hybrid pBR322 plasmid having a 4.2-kilobase insert of a DNA transcript of the mRNA of human plasminogen activator, urokinase. The bacterially produced enzyme has properties similar to those of urokinase from human fetal kidney cells. Both enzymes occur in discrete forms ranging from 32,000 to 150,000 daltons in size. They react with antibody to purified urokinase from human kidney cells, bind to a benzamidine-Sepharose column, and induce plasminogen-dependent lysis of a fibrin clot.

Base Sequence↗
PubMed1972

Detection and isolation of the repressor protein for the tryptophan operon of Escherichia coli.

DNA from a transducing bacteriophage carrying a fusion of the tryptophan and lactose operons of E. coli (lambdadtrp-lac) has been used to direct cell-free synthesis of beta-galactosidase (EC 3.2.1.23). Whereas normal lac operon (lambdadlac) DNA requires adenosine-3':5'-cyclic monophosphate (cAMP) for beta-galactosidase synthesis, trp-lac DNA is unaffected by cAMP. This difference in cAMP dependence verifies the presence of a cAMP-requiring promoter in the lac operon that has been removed from the trp-lac DNA. Synthesis with trp-lac DNA is controlled by the protein product of the tryptophan repressor gene (trpR). Synthesis in extracts of trpR(-) (repressor-negative) cells is progressively reduced by increased additions of extract from trpR(+) cells. No trpR(-) product repression is seen when beta-galactosidase synthesis is programmed by normal lac DNA. This highly sensitive and specific assay has facilitated quantitation and partial purification of the trp repressor.

Bacterial Proteins↗