Sodium Docecyl Sulfate Research Articles

Application of Derivative Variable-angle Synchronous Scanning Phosphorimetry in a Microemulsion Medium for the Simultaneous Determination of 2-Naphthoxyacetic Acid and 1-Naphthalenacetamide

The applicability of derivative variable-angle synchronous scanning (DVASS) microemulsion phosphorimetry at room temperature (ME-RTP) was demonstrated for the simultaneous determination of the plant growth regulators 2-naphthoxyacetic acid and 1-naphthalenacetamide in soil samples. This technique permits linear or non-linear paths to be scanned at preselected angles through the excitation–emission phosphorescence matrix in order to obtain the highest signal values and interference-free bands. The phosphorescence emission of the two compounds was obtained using sodium sulfite as an O 2 scavenger and thallium nitrate as an external heavy atom salt perturbed in sodium docecyl sulfate microemulsion aqueous solutions. A statistical model of the central composite design type to obtain the optimum phosphorescence responses was applied. The increased selectivity afforded by the DVASS technique permitted the demonstration of its applicability to the simultaneous determination of phosphorescent signals of these two compounds obtained in a microemulsion medium which show closely overlapped profiles giving mean recoveries of 89.0% (n = 5) for 1-naphthalenacetamide and 103.5% (n = 5) for 2-naphthoxyacetic acid, with an RSD of 7.35 and 5.90%, respectively, in real samples.

Comparison of three methods for extraction of viral nucleic acids from blood cultures

Reliable nucleic acid extraction techniques for blood specimens are required for the sensitive detection of viral DNA. Standardized procedures for processing blood specimens for the molecular detection of herpesviruses (cytomegalovirus [CMV], herpes simplex virus, varicella-zoster virus, and Epstein-Barr virus [EBV]) have not been established. Three methods were used to extract DNA from blood specimens from healthy donors and asymptomatic immunocompromised patients: (i) IsoQuick treatment of whole blood, (ii) extraction of the peripheral blood leukocytes by lysis (lysis buffer and proteinase K), and (iii) extraction of peripheral blood leukocytes with phenol-chloroform (sodium docecyl sulfate solution and proteinase K). All blood specimens from 25 healthy blood donors were negative for CMV, herpes simplex virus and varicella-zoster virus nucleic acid sequences, regardless of the extraction method, while three samples (12%) extracted by the lysis technique were positive for EBV DNA. Of 25 blood samples from asymptomatic immunocompromised patients, CMV and EBV each were detected in nine specimens by lysis extraction, four each by IsoQuick and four (CMV) and six (EBV) by the phenol-chloroform method. Our results indicate that the lysis method is optimal for the detection of CMV and EBV DNA sequences by PCR from the leukocytic fraction of blood specimens. DNA of these viruses is frequently present in blood specimens from asymptomatic immunocompromised patients and occasionally from healthy donors.

Gender differences and time course of castration-induced changes in porphyrins, indoles, and proteins in the Harderian glands of the Syrian hamster

Sexual differences and the effects of orchidectomy were determined for porphyrin and melatonin concentrations and for the activities of the enzymes N-acetyltransferase and hydroxyindole-O-methyltransferase, which synthesize melatonin from serotonin, in the Harderian glands of the Syrian hamster. Porphyrin concentrations in intact males were about 1/400th those of intact females. Castration for 1 week increased male Harderian porphyrin concentrations 10-fold; by 3 weeks, castrated male porphyrin levels were 140 times those of control values. N-Acetyltransferase activity in intact male Harderian glands was about 4 times that of females. Castration led to a drop in N-acetyltransferase activity to female levels within 2 weeks. Hydroxyindole-O-methyltransferase activity was 7 times higher in females than in males and castration had no effect on male Harderian hydroxyindole-O-methyltransferase activity. Neither gender nor castration influenced Harderian melatonin concentrations. Soluble proteins in Harderian glands from male and female hamsters and from male hamsters castrated for 1 and 4 weeks were examined by sodium dodecyl sulfate--polyacrylamide gel electrophoresis. The gel profiles revealed several differences among the protein distribution in male and female gland lysates. Orchidectomy led to a female protein pattern within 4 weeks.

High-performance liquid chromatography of levomepromazine (methotrimeprazine) and its main metabolites

The phenothiazine drug levomepromazine (methotrimeprazine) has five metablolites which previously have been identified in plasma from psychiatric patients. These are formed by sulphoxidation, N-demethylation, O-demethylation and aromatic hydroxylation in two different positions. A high-performance liquid chromatographic system is described for the analysis of levomepromazine and its main metabolities on a Supelcosil C 18-DB column, based on ion-pair formation with sodium docecyl sulphate. The effects of variations in pH, buffer concentration, counter-ion concentration, temperature and concentration and composition of the organic solvent were examined. The six components may be analysed in 27.4 min at room temperature using 25 m M sodium dodecyl sulphate in 500 m M ammonium acetate buffer (pH 5.0% v/v tetrahydrofuran in acetonitrile (50:50, v/v) as the mobile phase.

UDP‐glucose pyrophosphorylase from the plant fraction of nitrogen‐fixing soybean nodules

UDP‐glucose pyrophosphorylase (EC 2.7.7.9) has been highly purified from the plant fraction of soybean (Glycine max L. Merr. cv Williams) nodules. The purified enzyme gave a single polypeptide band following sodium docecyl sulphate polyacryla‐mide gel electrophoresis, but was resolved into three bands of activity in non‐denaturing gels. The enzyme appeared to be a monomer of molecular weight between 30 and 40 kDa. UDP‐glucose pyrophosphorylase had optimum activity at pH 8.5 and displayed typical hyperbolic kinetics. The enzyme had a requirement for divalent metal ions, and was highly specific for the substrates pyrophosphate and UDP‐glucose in the pyrophosphorolysis direction, and glucose‐1‐phosphate and UTP in the direction of UDP‐glucose synthesis. The Km values were 0.19 mM and 0.07 mM for pyrophosphate and UDP‐glucose, respectively, and 0.23 mM and 0.11 mM for glucose‐1‐phosphate and UTP. The maximum velocity in the pyrophosphorolysis direction was almost double that for the reverse reaction. UDP‐glucose pyrophosphorylase did not appear to be subject to a high degree of fine control, and activity in vivo may be regulated mainly by the availability of the substrates.

Circular dichroic, infrared and other studies on the protein component of pig brain thromboplastin.

1. A four-step procedure used to isolate the protein component (apoprotein III) of pig brain thromboplastin yielded approximately 25 mg from 500g of brain. 2. In the absence of detergent, apoprotein III had an apparent mol.wt. of 360 000 by gel-filtration, and, after electrophoresis on polyacrylamide gels in the presence of sodium docecyl sulphate, it appeared as a major protein band of mol.wt.59 000, suggesting the existence of polymeric and monomeric forms. 3. Chemical analyses of apoprotein III revealed that hydrophilic and hydrophobic amino acids were present in a ratio of 3:2, together with approx, 9% (w/w) of carbohydrate. 4. The far-u.v.c.d. and i.r. spectral data indicated that, like other membrane proteins, apoprotein III has a high percentage of unordered structure with lesser amounts of alpha and beta-forms. 5. Relipidation of apoprotein III to restore clotting activity caused no extensive alteration in the c.d. and i.r. spectra, indicating that the phospholipid associates with a comparatively small hydrophobic segment. The constrained unordered conformation, which makes the major contribution to the c.d. spectrum, probably forms a separate domain in the aqueous phase. The absence of any increase in the amplitude of both negative c.d. extrema, following relipidation, contrasted with the substantial increase observed in a helix-forming solvent and raises the possibility that the more stable polymeric form of apoprotein III is retained as the active form in the lipid phase. 6. We suggest that as a consequence of cell membrane damage, the recognition and activation of factor VII may involve minor changes of conformation that are dependent upon the flexibility inherent in an unordered secondary structure.

Lysis of Escherichia coli with a neutral detergent

1. When Escherichia coli cells are treated with lysozyme and versene for 30–45 sec in an ice-bath, they become susceptible to lysis by the neutral detergent Brij-58. 2. The rate of lysis is dependent upon the concentration of the detergent. Brij-58 is approx. 1000-fold less active in lysis of the lysozyme-versene-treated cells than is deoxycholic acid or sodium docecylsulphate. 3. The extent of cell disruption is dependent upon the Mg 2+ concentration and the ionic strength at the time of lysis. In 70 mM Mg 2+, only the low molecular weight soluble RNA and soluble protein are released from the cell. In 40 mM Mg 2+, the 70-S monosomes and the ribosome subunits are released together with the soluble material. At still lower Mg 2+ concentrations, the polyribosomes are released. 4. Unless the Mg 2+ concentration is reduced below 5 mM, the cellular DNA, after lysis, may be almost completely sedimented by centrifugation at 3000 × g for 5 min. 5. All strains of E. coli tested were susceptible to lysis by this method.

Studies on cytochrome a VII. Physico-chemical properties of purified cytochrome a

This paper gives results of an investigation on the homogeneity and molecular state of preparations of cytochrome a solubilized with surface-active agents and studied by sedimentation experiments and electrophoresis. The sedimentation pattern of cytochrome a in the presence of the non-ionic detergent. Emasol 1130, shows a single homogeneous and symmetric monodispersed component, whereas in the presence of the ionic detergent, sodium cholate, the protein behaves as a polydispersed, aggregated system. Based upon experimental results indicating a sedimentation coefficient of 21.9 S, a diffusion constant of 3.58·10 −7 cm 2/sec and a partial specific volume of 0.72 ml/g, it si calculated that cytochrome a solubilized with Emasol 1130 has a molecular weight of approx. 530 000, whereas its minimum molecular weight calculated from its iron content is 100 000. Thus the existence of the rigid structure of a pentamer is indicated. It was, furthermore, found that by treatment with reagents such as sodium docecyl sulfate or urea the protein is split into smaller subunits. Based on these results, the molecular state of cytochrome a is discussed.