Latex Extraction

The purification of glutamine cyclotransferase from papaya latex has been carried out by Messer and Ottesen (116). A batch procedure was used for the removal of impurities by passage of a papaya latex extract through a thin layer of carboxymethyl-Sephadex the active protein was separated by selective elution. Additional purification was achieved by chromatography on a column of carboxymethyl-Sephadex and by gel filtration on Sephadex G-100. The purified enzyme was homogeneous by the criteria of paper electrophoresis, ultracentrifugation, and gel filtration on Sephadex G-100 columns and chromatography on carboxy-methyl- or DEAE-Sephadex. The electrophoretic behavior of the enzyme indicates that it is a basic protein with an isoelectric point near... 

It is obtained from latex extracted from the Hevea brasiliensis tree. There exists another structural isomer called gutta-percha formed from po y trans-1,4-isoprene), whose elastic properties differ from those of natural rubber. 

Leynadier F, Herman D, Vervolet D, Andre C. Specific immunotherapy with a standardized latex extract versus placebo in allergic health care workers. J Allergy Clin Immunol 2000 106 585-590. 

R Wahl, T Fuchs. Serological diagnostic of natural latex allergy and molecular characterization of a natural latex extract. Allergologie 9 374-378, 1995. 

Aloe latex extract (up to 1000 mg/kg) administered to pregnant rats did not demonstrate any embryotoxic, fetotoxic, or teratogenic activity (ESCOP 2003). Some fetal abnormalities were noted in fetuses of pregnant albino rats fed an extract of ground aloe vera leaf on days 0 through 9 of gestation (Nath et al. 1992). 

The first material known as rubber was a polyisoprene produced from latex extracted from Hevea brasiliensis trees. Currently latex world production is concentrated in three areas Asia (93,3%), Africa (4,5%) and Latin America (2,2%). In Latin America the production reaches 195,000 tons, subdivided between Brazil, Ecuador, Guatemala and Mexico, and 54% of this production refers to Brazilian supply, with approximately 105 thousand tons, representing 1.2% of world production." ... 

NR can be included in the list of materials with possibility of application on nanostructures synthesis by green chemistry. In literature is possible to find the synthesis of nanoparticles using latex extracted from other trees of Euphor-biaceae family, such as Jatropha curcas as well as the seed extract used as liquid compound and inserted direetly into an aqueous solution of AgNOa. 

An essentially pure extracellular glycoprotein proteinase inhibitor was isolated from the latex of green fruits of papaya by a single affinity chromatography purification step. An immobilized trypsin-Sepharose CL 4B column was prepared according to the manufacturer (Amersham Pharmacia Biotech), which provided elaborated bulletins for the preparation procedures and applications of these affinity gel columns. Latex extract was applied to the column after equilibration with 20 mM Tris-HCl, pH 8.0, containing 0.5 M NaCl and 0.05 M CaCli. The column was extensively washed with the same buffer until ultraviolet (UV) absorbance became undetectible. The bound trypsin inhibitor was eluted with 0.02 M HCl and recovered by lyophilization after dialysis against water. 

The organic peroxide curing system was used to cure films made fi om latex extracted from different guayule lines and plant parts as well as from Hevea samples. Performance parameters (Table 6) indicate that good quality films can be made from different guayule lines, and from stem latex and latex extracted from the roots and stem bases. 

Gloves from different manufacturers were used for protein extraction, and salt precipitation, while hydrophobic interaction chromatography (HIC) was applied to obtain the enriched latex extracts [39. The major latex allergens were quantified by an enzyme immunoassay. The extracts obtained were tested in 14 volunteers using skin prick test (SPT). 

Latexes of synthetic resins are identified by ir spectrometry. Selective extraction with organic solvents is used to obtain purified fractions of the polymers for spectrometric identification. Polymeric films can be identified by the multiple internal reflectance ir technique, if the film is smooth enough to permit intimate contact with the reflectance plate. TAPPI and ASTM procedures have not been written for these instmmental methods, because the interpretation of spectra is not amenable to standardization. 

Membrane-retained components are collectively called concentrate or retentate. Materials permeating the membrane are called filtrate, ultrafiltrate, or permeate. It is the objective of ultrafiltration to recover or concentrate particular species in the retentate (eg, latex concentration, pigment recovery, protein recovery from cheese and casein wheys, and concentration of proteins for biopharmaceuticals) or to produce a purified permeate (eg, sewage treatment, production of sterile water or antibiotics, etc). Diafiltration is a specific ultrafiltration process in which the retentate is further purified or the permeable sohds are extracted further by the addition of water or, in the case of proteins, buffer to the retentate. 

Porous membranes with selective permeabiUty to organic solvents have been prepared by the extraction of latex films prepared with moderate ratios of PVA—PVAc graft copolymer fractions. The extracted films are made up of a composite of spherical cells of PVA, PVAc microgel, and PVA—PVAc graft copolymers (113). 

Guayule, potentially a source of natural mbber, is an unusual crop in that it has been an article of commerce in the past. Guayule grows wild in northern Mexico and the southwestern United States. When the leaves are milled in water, a latex is released that coagulates into natural mbber worms. These can easily be collected and relatively easily refined to give a product that is almost identical to the natural mbber from southeast Asia. During World War II there were several thousand acres of guayule planted in California and a small plant estabUshed to extract the mbber for military use. After the war. 

Type of dryer tions, extracts, milk, blood, waste liquors, rubber latex, etc. gents, calcium carbonate, bentonite, clay sbp, lead concentrates, etc. trifuged sobds, starch, etc. dry. Examples centrifuged precipitates, pigments, clay, cement. ores, potato strips, synthetic rubber. objects, rayon skeins, lumber. sheets. her sheets. 

We have found that in the system of presulfate initiator, the PVAc latexes are not dissolved transparently in the methanol-water mixture [8], and in the system of HPO initiator, the extraction of the polymer from the PVAc latex films with acetone greatly depends on the polymerization condition [9]. These results suggest that if a polymerization method can be found in which the grafting polymerization of VAc onto PVA is controlled to the minimum, a large portion of PVAc in the latex film will have a chance of extraction with solvents. In this Chapter, the preparations of the unique porous films from the PVAc latexes containing PVA as a protective colloid by an extraction of the PVAc particles with acetone and the characteristic properties of the porous films are summarized. 

The PVAc latex was cast 1.8 mm in thickness on a poly(-ethylene) plate and dried at room temperature. The latex film was dried further in a vacuum desiccator for 24 h, and extracted in Soxhlet extractor with acetone for 20... 

Judging from the extraction percentage of PVAc and from the swelling degree of latex films in acetone, it is... 

Figure 2 Electron microphotographs of crack surface (a) and (b) and upper surface (c) and (d) of PVAc latex film. Acetone extraction (a) and (c) before, (b) and (d) after.

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