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H R Lill

Publications and source records attributed to H R Lill.

3 recordsLinked to original sources
PubMed1981

Isolation of a second rifamycin-binding from Escherichia coli by affinity chromatography.

When extracts of Escherichia coli are filtered through a Sepharose column containing covalently bound rifamycin a protein is bound which can be eluted either with a high concentration of urea or more specifically with low concentrations of rifamycins. Its Mr is 18,000 +/- 1,000 in the presence of dodecylsulfate, in its absence 36,000 +/- 3,000. The association constant of the protein for rifampicin is 2.4 +/- 0.5 x 10(-4) M with two binding sites per dimer as determined by equilibrium dialysis. Large amounts of this protein are released from the cells by an osmotic shock.

Binding Sites↗
PubMed1975

Digestion with matrix-bound proteases as a possible probe for the topography of the DNA-dependent RNA polymerase from Escherichia coli.

DNA-dependent RNA polymerase lacking subunit sigma was digested with matrix-bound chymotrypsin or trypsin in the presence of 0.4 M NaCl in the monomeric form or at low ionic strength in the oligomeric form. Sigma-containing polymerase was digested in the same way. The course of proteolysis was followed by polyacrylamide gel electrophoresis after dissociation of the enzyme with detergent into subunits and the fragments produced by the hydrolysis. The following results were obtained. (a) The large subunits beta and beta' are cleaved with a much higher rate in the monomeric than in the oligomeric polymerase. (b) Both large subunits are hydrolysed with the same rate. (c) Subunit alpha is hydrolysed almost with the same rate in the monomeric and oligomeric form of polymerase. (d) The same was found for subunit sigma. (e) These effects were independent of the substrate specificity of the protease used. (f) Subunit sigma is much more susceptible to chymotrypsin than to trypsin. (g) Subunit sigma protects the large subunits beta and beta' against tryptic cleavage. These results can be explained in terms of a tentative model for the topography of the protomer-protomer interactions in RNA polymerase. According to this model subunits beta and beta' contain two sites for isologous interactions of protomers. One site can be blocked by attachment of subunit sigma. Subunits alpha and sigma do not participate directly in the association.

Acrylamides↗