Cell walls extraction

All cell-wall extracts contained several PME isoforms differing in their isoelectric points. The isoenzyme patterns changed significantly during cell ageing. 

Figure 3. PME isoform patterns in cell wall extracts fiom active and resting cells, a cell wall extracts from successive segments (A, B, C and D) sectioned along mui bean hypocotyb and exhibiting decreasing elongation rates a, and y m c the main PME isoforms present in the extracts, tteir pi are respectively around 7.5, S.5 and above 9.1. b cell wall extracts obtained from poplar cambium and inner bark tissues during cambial active (may) and rest (december and march) periods 1, 2 and 3 represent the activity of 3 groups of PME isoforms with pi around 5-6, 7.5 and above 9.1. Activities expressed as percent of total PME activity present in each extract.

Fig. 23 Saliva and serum IgA (primary and secondary) response following orally administered soluble antigen Streptococcus mutans cell wall extract (open circles, soluble antigen solid circles, liposome-encapsulated material) (phosphatidylcholine, phosphatidic acid, cholesterol). (From Ref. 277).

Following a stimulation by the yeast cell wall extract zymosan, phagocytosing human leukocytes show an enhanced oxygen consumption, the cyanide-insensitive respiratory burst , after a lag period of 30-40 s. The production of superoxide anions, measured by the reduction of Fe(ni)-cytochrome c, followed the same... 

Within the extracts (thermal or enzymatic), besides polysaccharides, mannoproteins were proven to be the main components, the molecular characterization of which has been carried out using SEC and SDS-PAGE (Martfnez-Rodrfguez et al. 2007 Nunez et al. 2006). Results showed in both cell wall extracts a protein band corresponding to a relative molecular mass of 30kDa (Eig. 5.9). Moreover, three bands, which were absent from the extract obtained enzymatically, with relative molecular masses between lOkDa and 21.5 kDa were observed in the thermal extract. Only glycoproteins with Mr between 10 kDa and 21.5 kDa, were proven to be foam-active though the protein at 30 kDa (also present in the enzymatic extract) was found to be inactive. 

In addition to chitin, a polysaccharide-containing cell-wall extract, termed trichophytin, was obtained by Bloch and coworkers from dermatophytes. As part of an immunological study. Bishop, Blank, Perry, and others " have conducted investigations on the structural units contained in the constituent polysaccharides. 

Hoppe-Seyler s Zeitschrift fur Physiologische Chemie, 346, 296-8 Klis, F.M., Tegelaers, F. Hazenberg, C.A.M. (1979) Cell Wall Extractable... 

Elicitors are often apphed in the form of crade mixtures, such as a fungal cell wall extract. In a few eases, ehdtors have been purified to... 

Success in structural studies of cell walls depends largely on the purity and homogeneity of the cell wall preparations examined. Some studies have been made of primary cell walls extracted from whole plant tissues. Since all tissues of intact plants contain a variety of cell types, the walls prepared from these tissues are not homogeneous. The desire for homogeneous wall preparations has been satisfied by use of suspension-cultured cells. Suspension-cultures, of at least some types of plant cells, can be maintained in a totally undifferentiated state. These types of suspension cultures provide a source of homogeneous primary cell walls. 

Agar occurs as a cell-wall constituent of the red marine algae Rho ophyceae, from which it is extracted by hot water, and marketed as a dry powder, flakes, or strips. It dissolves in hot water and sets on cooling to a jelly at a concentration as low as 0-5%. Its chief uses are as a solid medium for cultivating micro-organisms, as a thickener, emulsion stabilizer in the food industry and as a laxative. 

Silicon is important to plant and animal life. Diatoms in both fresh and salt water extract Silica from the water to build their cell walls. Silica is present in the ashes of plants and in the human skeleton. Silicon is an important ingredient in steel silicon carbide is one of the most important abrasives and has been used in lasers to produce coherent light of 4560 A. 

Pectin. Pectin [9000-69-5] is a generic term for a group of polysaccharides, mainly partially methoxylated polygalacturonic acids, which are located in the cell walls of all plant tissues. The main commercial sources of pectin are citms peel and apple pomace, where it represents 20—40% and 10—20% of the dry weight respectively. The pectin is extracted, the extract purified, and the pectin precipitated (50) increased extraction times lead to the production of low methoxyl pectins. 

Hemicellulose [9034-32-6] is the least utilized component of the biomass triad comprising cellulose (qv), lignin (qv), and hemiceUulose. The term was origiaated by Schulze (1) and is used here to distinguish the nonceUulosic polysaccharides of plant cell walls from those that are not part of the wall stmcture. Confusion arises because other hemicellulose definitions based on solvent extraction are often used in the Hterature (2—4). The term polyose is used in Europe to describe these nonceUulosic polysaccharides from wood, whereas hemicellulose is used to describe the alkaline extracts from commercial pulps (4). The quantity of hemicellulose in different sources varies considerably as shown in Table 1. 

Extraction of proteia requires breaking the cell wall to release the cytoplasmic contents. This can be achieved by high speed ball or coUoid mills or by high pressure (50—60 Mpa) extmsion. Proteia is extracted by alkaline treatment followed by precipitation after enzymatic hydrolysis of nucleic acids. Although the proteia can be spun iato fibers or texturized, such products are more expensive than those derived from soybean and there is no market for them. 

Detergent Methods. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) methods (2), later modified for human foods (13), measure total insoluble plant cell wall material (NDF) and the cellulose—lignin complex (ADF). The easily solubilized pectins and some associated polysaccharides, galactomaimans of legume seeds, various plant gums, and seaweed polysaccharides are extracted away from the NDF. They caimot be recovered easily from the extract, and therefore the soluble fiber fraction is lost. 

Lysozyme, extracted from egg whites, is an enzyme that cleaves bacterial cell walls. A 20.0-mg sample of this enzyme is dissolved in enough water to make 225 mL of solution. At 23°C the solution has an osmotic pressure of 0.118 mm Hg. Estimate the molar mass oflysozyme. 

Cell wall lysed with organic solvent extraction... 

Xyloglucans are classified as gum when they are extractable with hot water from seed endosperm cell walls, such as the tamarind seed xyloglucan, and as hemicelluloses because they are alkali-extractable from the cell walls of vegetative plant tissues where they are closely associated with cellulose [2]. Also /3-glucans with mixed linkages appear under the name gum as well as hemicellulose in the literature. 

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