Glucose oxidase/lactoperoxidase

Figure 12.6 The immobilized glucose oxidase/lactoperoxidase system radioiodinates proteins through the intermediate formation of hydrogen peroxide from the oxidation of glucose. H2O2 then reacts with iodide anions to form reactive iodine (I2). This efficiently drives the formation of the highly reactive H2OI+ species that is capable of iodinating tyrosine or histidine residues (see Figure 12.2).

The glucose oxidase-lactoperoxidase (GO-LPO) iodination method of Tower et al. was used to produce [ I]hPRL. After purification on a column of Sephadex G-lOO, the major peaks of iodinated material were screened for use in RIA by the talc-resin-TCA test (Fig. I). Peak III material obtained from the Sephadex G-lOO gel filtration purification was the... 

Talc-Resin-Trichloroacetic Acid (TCA) Test Results for -I-Labeled Hormones Prepared by the Glucose Oxidase-Lactoperoxidase (GO-LPO) Iodination Method ... 

Fig. 3. Elution pattern of I-labeled rat prolactin, [ I]rPRL (AFP 1-2), prepared by the glucose oxidase-lactoperoxidase iodination procedure and purified as described in Pig. I for human PRL. The unlabeled hormone was stored as a dry powder, desiccated, and weighed out just prior to iodination this resulted in a maximum yield of peak III material. The peak III monomeric hormone is suitable for use in radioimmunoassay (cf. Fig. 4) (Tower er o/. ).

Fig. 5. Identical standard curves obtained from human prolactin (hPRL) (VLS No. 4) iodinated by the glucose oxidase-lactoperoxidase method and purified as described in Fig. 1. One standard curve (O—O) was obtained with freshly prepared peak III iodoprolactin on the day of iodination. The other standard curve ( — ) was obtained from peak III material from the same iodination, which then had been stored at - 20° for 3 months before use in radioimmunoassay. Before storage, 50 mg of resin and 100 /il of 5% BSA had been added to each 2-ml fraction of the peak III material. Both standard curves were obtained with AFP No. 1 hPRL antiserum and AFP No. 1 hPRL standard. In both instances the nonspecific binding was 3% and the initial binding (B/T) was 32% (Tower et al. ).

Amylase bromelain catalase glucose oxidase lactoperoxidase lipase papain pepsin superoxide dismutase urease... 

Glucose oxidase, in combination with peroxidase or lactoperoxidase Polynucleotide phosphorylase... 

Since the principal constituents of milk are proteins, lipids and lactose, proteinases, lipases and / -galactosidase (lactase) are the principal exogenous enzymes used in dairy technology. Apart from these, there are, at present, only minor applications for glucose oxidase, catalase, superoxide dismutase and lysozyme. Lactoperoxidase, xanthine oxidase and sulphydryl oxidase might also be included, although at present the indigenous form of these enzymes is exploited. 

Cell Membrane Labeling. Five million line-10 tumor cells are washed 3 times with 25 ml of PBS, resuspended in 0.4 ml of PBS, and incubated with 10 /ag of lactoperoxidase, 3 mU of glucose oxidase, 2.5 yM glucose (0.23 /xg), and 100 /xCi of Na I in a total volume of 0.5 ml for 15 min at ambient temperature. The cells are washed 5 times with 10 ml of PBS, and the lipid and nonlipid fractions of the cells are obtained through a Folch extraction. The cellular lipids are separated by thin layer chromatography. ... 

The oxidation of iodide is performed by enzymes of the peroxidase type (Morrison, 1980), mainly lactoperoxidase, but also by horseradish peroxidase, microperoxidase and chloroperoxidase, which are hemoproteins with tetrapyr-rolic cores chelating iron. These enzymes are active in the presence of small amounts of hydrogen peroxide or glucose oxidase. They form a first complex with H2O2 that... 

Kawakami K, Nagamatsu S, Ishii M et al. (1986) Enzymatic formation of propylene bromohydrin from propylene by glucose oxidase and lactoperoxidase. Biotechnol Bioeng 28 1007-1013... 

The separation of lactoperoxidase from the labeled protein may be avoided by using the immobilized enzyme (David and Reisfeld 1974). This technique applies immobilized lactoperoxidase together with glucose oxidase, which produces H2O2 in the presence of glucose. 

Enzymatic oxidizing systems are capable of generating reactive oxygen species as well. The system Myavert C uses a balance of lactoperoxidase and glucose oxidase to yield preservation in cosmetic and toiletry formulations (Guthrie, 1992). For optimum performance a target pH of between 4 and 6 should be considered. 

Zhou, Y. Lim, L. T. (2009). Activation of Lactoperoxidase System in Milk by Glucose Oxidase Immobilized in Electrospim Polylactide Microfibers. Journal of Food Science, 74(2), C170-C176. 

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