Action Of Sodium Dodecyl Sulfate Research Articles

Interaction of sodium dodecyl sulfate and of non-ionic detergents with S-carboxyamidomethyl- κ-casein

Sodium dodecyl sulfate binds to S-carboxyamidomethyl- κ-casein in a highly cooperative manner at a concentration near the critical micelle concentration, showing a strong dependence on ionic strength. The maximum number of sodium dodecyl sulfate molecules bound is attained above the critical micelle concentration, and is very close to the micelle aggregation number in the absence of protein. The binding sites on the protein for sodium dodecyl sulfate are localized mainly on para- k-casein part, which is a hydrophobic fragment of κ-casein produced by rennin attack. The mode of the action of sodium dodecyl sulfate on S-carboxyamidomethyl- κ-casein resembles that of several integral membrane proteins, rather than of water soluble proteins. On considering possible situations, it is suggested that the unusual interaction of S-carboxyamidomethyl- κ-casein with sodium dodecyl sulfate is responsible for an anomalous migration of reduced κ-casein observed in sodium dodecyl sulfate polyacrylamide gel electrophoresis. Further, the suggestion was made by the binding studies of sodium dodecyl sulfate and non-ionic detergents that the sites which were involved in self-association of S-carboxyamidomethyl- κ-casein participated in the binding sites of detergents.

Comparative study on conformational stability and subunit interactions of two bacterial asparaginases

The denaturation and reconstitution of Erwinia carotovora and Escherichia coli l-asparaginases has been followed by optical rotatory dispersion, circular dichroism and analytical ultracentrifugation. Denaturation in urea results in dissociation of the native enzyme (mol. wt. 140 000 approx.) to produce unfolded subunits (mol. wt. 35 000 approx.); the Erwinia l-asparaginase subunits can be refolded by dilution or dialysis in alkaline conditions, pH 10.5, without aggregation to the active tetramer, to give a rather unstable solution of a monomer possibly in equilibrium with dimer. These alkaline-reconstituted subunits undergo a conformational change to a more ordered state in the presence of sodium dodecylsulphate, similar to those produced by the action of sodium dodecylsulphate on the native enzyme. If the denatured subunits are reconstituted in the pH range 5.0–7.5, the enzymically active tetramer is reformed in up to 80% yield, depending upon the conditions of temperature and concentration. Kinetic data for these various transitions suggest that dissociation is a rate-limiting step while conformational changes of the polypeptide chains are relatively much more rapid. The possible significance of these different rates of change to therapeutic considerations is discussed.

Specific role of sex pili in the effective eliminatory action of sodium dodecyl sulfate on sex and drug resistance factors in Escherichia coli.

Evidence is presented for the specific role of sex pili in the eliminatory action of sodium dodecyl sulfate (SDS) on sex (F) and drug resistance (R) factors in Escherichia coli K-12 strains leading to their loss. SDS at 0.03% concentration lysed JE3100 F(8) (+) (F-gal)/gal(-)fla(-)pil(-) in Penassay broth after they had grown exponentially and reached maximum growth to the extent that the agent at concentrations higher than 1% did. However, the agent was only effective in eliminating sex factors from JE3100 in high frequencies at concentrations higher than 1%. Increase of osmotic pressure of the culture with SDS at concentrations as low as 0.03 to 0.1% by addition of sucrose led to the substantial increase of elimination efficiency. Reconstruction experiments between F(8) (+) and F(-) cells in the SDS culture revealed the selective growth of F(-) cells as well as a delay of maximum growth of F(-) variants derived from F(8) (+) cells, compared with those of F(8) (+) cells, as well as F(-) cells originally added to the culture. The agent was not very effective in eliminating sex factors from JE3427 F(8)m(+)5/fla(-)pil(-) cells which lack the function of production of F pili. F(8)m(+)5 cells showed a sensitivity toward SDS intermediate between those of F(8) (+) and F(-) cells. SDS was further effective in eliminating R factors from KE132 R(100-1) (+)/fla(-)pil(-) cells in high efficiency; however, the action was not efficient with KE133 F(100) (+) cells possibly with fewer sex pili than R(100-1) (+). Action of acridine orange on these F(+) or R(+) strains was found to be different in some aspects from that of SDS.

Molecular organization in bacterial cell membranes: I. Sodium dodecyl sulphate solubilization and fractionation of the components of a depleted membrane from Micrococcus lysodeikticus

A method is presented for the solubilization and fractionation of Micrococcus lysodeikticus membrane after it has been subjected to mild washing procedures ( i.e. depleted membrane). The method involves the solubilization of the membrane, treatment with iodoacetamide and sodium dithionite and the action of sodium dodecyl sulphate on the membrane extracted with n-butanol. Polyacrylamide electrophoresis and Sephadex G-200 filtration in the presence of dodecyl sulphate result in the separation of at least eleven protein components whose molecular weights range from 17000 to 75000. Residual lipid and carbohydrate are found as components of the depleted membrane, and fractionated as a glycolipoprotein complex. A component tentatively identified as ribonucleic acid is also found associated with the membrane although its association with other membrane components appears to be broken by the detergent.

Specific action of sodium dodecyl sulfate on the sex factor of Escherichia coli K-12 Hfr strains.

A specific action of sodium dodecyl sulfate (SDS) on the sex (F) factor in the integrated state of Escherichia coli K-12 Hfr H strain is reported. Growth of Hfr cells in Penassay Broth containing SDS results in the elimination of part or all of the F factor, yielding low and nonfertile variants of defective Hfr type and F(+) cells and also F(-) derivatives. Appearance of such variants was generally observed after the culture reached stationary phase. The frequencies of F(-) cells then increased. F(-) cells were usually isolated as the major population among survivors. Some defective variants of Hfr cells with an intermediate fertility between standard Hfr and F(+) cells had lost sensitivity toward the male-specific ribonucleic acid phage M12. Other defective Hfr variants with as much or less fertility than standard F(+) cells had also all lost sensitivity to phage M12. On single-colony isolation, they segregated nonfertile female H cells which, when infected with F, could restore high fertility with oriented transfer of the chromosome the same as that of the original Hfr H. Also, sensitivity to phage M12 was regained. Female H cells were characterized as those lacking fertility but still retaining a small segment of F or sfa locus at the original part of the chromosome, where newly infected F could attach. Similar results were obtained with two other Hfr strains. A possible mechanism of the specific action of SDS is discussed.

The submolar quantities of N-terminals in proteins. Effect of sodium dodecyl sulfate on the N-terminals of egg albumin and bovine, equine, and procine γ-globulins

The quantities of the N -terminal amino acids of the proteins investigated were increased twofold to tenfold and more by action of sodium dodecyl sulfate in acid; serine and threonine were affected most. The limited action of trypsin caused an increase of the quantities of all the N -terminals of porcine γ-globulin. In all the cases investigated, although the quantities changed, no new N -terminal appeared beside the ones present in the untreated protein. The submolar quantities of the N -terminals of the proteins under study were not impurities; the increased quantities of N -terminals derived not from the uncovering of masked N -terminals because of denaturation, but more likely from a specific hydrolysis, which was catalyzed by trypsin and by the acidic alkyl sulfate. It is suggested that the N -terminals of a number of proteins may be the products of autolysis or hydrolysis (of particularly labile peptide bonds) which took place at various times during the physiological and laboratory history of the protein molecule.

A study of the effects and mechanism of action of sodium dodecyl sulphate on gastric secretion in rats.

A study of the effects and mechanism of action of sodium dodecyl sulphate on gastric secretion in rats.