Edwin H. Liu

Rapid Evolution in a Post-Thermal Environment

geographic variation patterns. Syst. Zool. 28:227232. -9, AND F. J. ROHLF. 1969. Biometry. W. H. Freeman and Co., San Francisco. STEARNS, S. C., AND R. D. SAGE. 1980. Maladaptation in a marginal population of the mosquitofish, Gambusia affinis. Evolution 34:65-75. WALLACE, B. 1968. Topics in population genetics. W. W. Norton and Co., New York. WRIGHT, S. 1980. Genic and organismic selection. Evolution 34:825-843.

Visualization of peroxidase isozymes with eugenol, a noncarcinogenic substrate

Abstract Plant peroxidase isozymes utilize hydrogen peroxide to oxidize redox dyes. Benzidine, the substrate most commonly used for identification of peroxidase isozymes, is a potent carcinogen and has been banned from laboratory use. O -Dianisidine, the other common substrate for peroxidase isozymes, is structurally related to benzidine and is a possible carcinogen. A peroxidase zymogram stain has been developed which uses eugenol, a substrate which is safe to use in the laboratory. Peroxidase isozymes are recognized as bright blue fluorescent bands under ultraviolet light and develop within 1 min after staining. Eugenol may also be used in a quantitative fluorimetric assay of peroxidase activity.

A simple method for determining the relative activities of individual peroxidase isozymes in a tissue extract

Abstract A peroxidase specific zymogram staining procedure has been designed which not only locates peroxidase isozymes which have been resolved electrophoretically, but simultaneously estimates the relative activity of each peroxidase isozyme in the system under study. This quantitative assay of individual peroxidase isozymes is chronometric; the time required for the appearance of a peroxidase band is inversely proportional to its activity. By recording the time required for the appearance of each peroxidase isozyme in a tissue extract, the percent contribution each isozyme makes toward the total peroxidatic activity of that tissue can readily be determined.

The inhibition of peroxidase and indole-3-acetic acid oxidase activity by British Anti-Lewisite

Abstract British Anti-Lewisite (BAL) binds to horseradish peroxidase in a manner which results in inhibition of both peroxidatic and oxidative functions of the enzyme. BAL competes with hydrogen peroxide for binding on peroxidase, and the inhibition of peroxidatic activity is irreversible. Solutions of purified horseradish peroxidase and individually resolved peroxidase isozymes show a gradual loss of peroxidatic activity with time when incubated with BAL. In these same treatments, however, the inhibition of indole-3-acetic acid (IAA) oxidase activity is immediate. With increasing amounts of enzyme in the incubation mixture, IAA oxidase activity is not completely inhibited and is observed following a lag period in the assay which shortens with longer incubation times. Peroxidase activity during this same time interval shows a lag period which increases with longer incubation times. Lowering the pH removed the lag period for oxidase activity, but did not change the pattern of peroxidase activity. These results suggest that the sites for the oxidation of indole-3-acetic acid and for peroxidatic activity may not be identical in horseradish peroxidase isozymes.

SUBSTRATE SPECIFICITIES OF PLANT PEROXIDASE ISOZYMES

ABSTRACT. Peroxidase (E. C. 1.11.1.7) utilized hydrogen peroxide to oxidize a wide range of hydrogen donors. Because this enzyme system consists typically of a large number of isozymes in plants, the possibility exists that the peroxidase system consists of a family of homologous enzymes which have different substrate specificities and perform different physiological functions in the cell.

Enzyme Levels in Natural Mosquitofish Populations

Adenosine deaminase (ADA), lactate dehydrogenase (LDH), and malate dehydrogenase (MDH) activity levels were measured in mosquitofish populations from contrasting natural environments. Significant differences in enzyme level, in the level of soluble protein, and in length and weight were observed among populations from different habitats. MDH and LDH activities were highest in running-water populations, whereas ADA was elevated in coastal environments. Still-water females were longer and weighed less than running-water females. The regression relationships of length vs. weight and protein vs. weight also varied significantly among populations. The proportion of enzyme activity variation which could be accounted for by habitat, location, or log length was not the same for the three enzymes, suggesting that biological and physical factors influence the activities of various enzymes in different ways.

A solid-phase radio-binding assay for the characterization of lectin recognition☆

A rapid and quantitative method for characterizing lectin specificity is presented. This assay is analogous to solid-phase radioimmune assays and utilizes the property of irreversible binding of proteins to vinyl microtiter plates. The lectins phytohemagglutinin and concanavalin A bind to vinyl and retain their biological properties. Iodinated fetuin and immunoglobulin G are both bound by the immobilized lectins. Competing amounts of ligands presented at the same time as the iodinated glycoproteins are shown to reduce binding to the immobilized lectins. Conversely, glycoprotein ligands immobilized to vinyl retain their ability to be recognized and bind lectins. The solid-phase binding assay can be used to characterize the ligand-binding specificity of lectins. For example, the pattern of glycoprotein inhibition of the binding of iodinated gorgonian lectin from Leptogorgia virgulata to insolubilized thyroglobulin is virtually identical to the pattern reported previously using hemagglutination inhibition. The solid-phase radio-binding assay is rapid, reproducible, and sensitive to nanogram quantities of ligand added. Most importantly, it provides quantitative information on lectin recognition.

Characterization of a hemagglutinin from Leptogorgia virgulata

Abstract 1. 1. Extracts of the marine coral Leptogorgia virgulata possess potent hemagglutination activity. 2. 2. The hemagglutination activity is both heat and protease sensitive. 3. 3. The hemagglutination activity requires the divalent cation, Ca 2+ . 4. 4. Competitive inhibition experiments with complex carbohydrates indicate that this hemagglutinin recognizes a glycosyl aspect on the oligosaccharides of thyroglobulin glycopeptides, submaxillary mucin and human IgG. 5. 5. Other glycoconjugates were effective as inhibitors only after desialylation of the oligosaccharides.