Isoenzymes of lipoxidase

A polyacrylamide disc gel electrophoretic technique is described for studying isoenzymes or multiple molecular forms of lipoxidase in extracts of fresh green peas, pea seeds, wheat, fresh green beans and green bean seeds. After electrophoresis, gels containing starch were incubated with linoleic acid. Hydroperoxide bands were visualized by treating the gel with acidic potassium iodide. Staining specificity was established using the following criteria. Activity was absent when extracts or gels were boiled and when linoelaidic and oleic acids were used as substrates. Cyanide did not inhibit staining, whereas α-tocopherol, hydroquinone and nordihydroguaiaretic acid did. Prevention of the appearance of artifactual bands was attempted by: pre-electrophoresis of the gels; electrophoresis in the presence of thioglycollic acid; elimination of the large pore gel; pH adjustment of the plant extracts; and extraction of extract solids with lipid solvents. Gel patterns indicated two to three lipoxidase bands for fresh green peas and pea seeds, one to two bands for fresh green beans and green bean seeds, and four bands for wheat.     

Identification of betanin degradation products

Betanin in solution, upon heating, was found to hydrolyze to betalamic acid and cyclodopa-5-O-glycoside. This reaction was monitored by an analytical high performance liquid chromatography (HPLC) method. The products were isolated by preparative reversed-phase HPLC or column chromatography using anion-exchange resins. Derivatives of betalamic acid (anilide, semicarbazone, condensation with L-proline) and cyclodopa-5-O-glycoside (hexacetate) were prepared as evidence to support the identification of these decomposition compounds. Formation of decarboxylated betanin was proposed based on the identification of CO2, chromatographic properties and the light absorption characteristics of the decarboxylated product.     

Oxygen involvement in betanine degradation—Measurement of active oxygen species and oxidation reduction potentials

The possible involvement of active oxygen species in the degradation of betanine was investigated using a variety of chemical and enzymatic tests. Neither singlet oxygen nor superoxide anion were implicated in the oxidative degradation of betanine. Betanine was destroyed in solutions containing photosensitized riboflavin. Oxidation—reduction (redox) potentials were measured in solutions containing betanine or its aglycone, betanidin. The lower potential of betanidin, relative to betanine, coincided with a greater susceptibility of the aglycone to destruction by molecular oxygen.     

Reduktive alkylierung von azobenzol

The electrochemical reduction of azobenzene in the presence of some α,ω-dibromoalkanes led to the corresponding cyclic hydrazo compounds. Mono- and diallylated hydrazobenzene could be isolated by adding allylchlorides. The preparative aspects of these experiments are discussed.     

Autoantibodies to desmoplakin I and II in patients with erythema multiforme

Erythema multiforme (EM) represents a syndrome of chronic recurrent inflammatory skin disease. Depending on the severity and extent of skin and mucosal involvement, it is defined either as EM minor or EM major. In this study we demonstrate the presence of autoantibodies (aAbs) against desmoplakin I and II, two major proteins of the desmosomal plaque, in six of six patients with the severe variant of EM, EM major. Light microscopic studies of lesional skin and mucous membranes localized in vivo bound immunoglobulin G (IgG) in a dotted desmosomal pattern along the cytoplasmic membranes of keratinocytes. By immunoelectronmicroscopy, in vivo bound IgG was confined to the desmosomal plaques. These findings were confirmed by indirect immunolocalization studies that demonstrated the presence of IgG aAbs in the serum of patients during active disease. These aAbs did not only bind to desmosomal plaques of epithelial cells where they colocalized with defined murine monoclonal antibodies directed against desmoplakin I and II, but also labeled the intercalated discs of myocardial cells. Biochemical characterization of circulating IgG aAbs revealed desmoplakin I and II as actual target autoantigens. By passive transfer of serum into newborn mice, in vivo binding of serum aAbs to keratinocytes was shown. The findings presented in this study imply a humoral immune response in certain patients with EM major and indicate a potential pathogenetic role of aAbs against desmoplakin I and II in this disease.     

Electrochemical reductive alkylation of benzil

The electrochemical reduction of benzil in dimethylformamide (DMF) in the presence of different alkylating agents and supporting electrolytes lead to the formation of products derived from alkylation at oxygen (E-and Z-dialkoxy stilbene), alkylation at carbon (alkylated benzoin derivatives) and from a reaction with the solvent DMF followed by alkylation and cyclisation to 2-methoxy-4,5-diphenyl-1,3-dioxole. The relative amounts of these products depend very much on the supporting electrolyte, the alkylating agent and its concentration. LiCl in small concentrations, (C₂H₅)₄NCl and large excess of dimethyl sulfate favor the formation of the dioxole derivative. LiCl in larger concentrations and alkylating agents other than dimethyl sulfate favor alkylation at oxygen and/or carbon. The results of the preparative electrolysis under various conditions are described.