Shear thickening of DNA in SDS lysates.

Cells of Escherichia coli were subjected to lysis by an alkali detergent treatment (sodium dodecyl sulphate). The rate of detergent lysis was not first order. The rheological properties of the lysate were measured using a controlled stress rheometer. Detergent-lysed cells produced a lysate which showed marked non-Newtonian properties. The material showed a shear thickening at specific low shear stress conditions. The acceleration of the cone during the ascent stage of a flow curve, influenced the shape of the flow curves. These findings are discussed in relation to the form of bacterial DNA in solution.     

Iron: a possible heterotropic effector of prolyl hydroxylase.

The mechanism of ferrous ion binding to prolyl hydroxylase (prolyl-glycyl-peptide,2-oxoglutarate:oxygen oxidoreductase, EC 1.14.11.2) was studied according to Koshland's curve-fitting procedure (Cornish-Bowden, A. and Koshland, Jr., D.E. (1970) Biochemistry 9, 3325--3336). The calculated data obtained by means of the unrestricted Adair equation were found to provide an adequate fit with experimentally obtained values, whereas those obtained on the basis of Michaelis-Menten kinetics did not. This suggests that prolyl hydroxylase could be an allosteric enzyme under positive heterotropic control.