Substances, pectic

Pectin and related substances are widespread in the plant kingdom. They are normally obtained from the dilute acid extract of the inner portion of citrus peels or from apple pomace. The extraction of pectin is carried out at elevated temperatures at a controlled pH. The process must be very carefully checked in order to avoid a possible hydrolysis of glycosidic and ester linkages. The crude extract is concen- 

Commercial pectin is a fine, yellowish white, almost odorless powder with a mucilaginous taste. It is completely soluble in twenty parts of water giving an acidic, viscous, and opalescent solution. 

Pectin is mainly used as a suspending agent and is an ingredient in many anti-diarrheal formulas. As a colloidal solution, it conjugates toxins and enhances the physiological functions of the intestinal system through its physical and chemical properties. 

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PEC-1000 Pechmann reaction Peclet numbers PE coatings Pectic acid Pectic acids [9046-40-6] Pectic materials Pectic substances Pectin... 

The common hemiceUulose components of arborescent plants are listed in Table 3. Xylans, arabinogalactans, and pectic substances are common to all while only traces (if at all) of glucomaimans are found in the cell walls of bamboo. Other polysaccharides are found in trace amounts in wood as well as in bark, growing tissues, and other specialized parts of trees. 

Most of the pectin ia the cotton fiber is ia the primary wad. Removal of the pectic substances is accompHshed by scouting, which does not change the properties of the cotton greatiy. 

Pekannuss, /. pecan nut, pecan, pektin-artig, a. pectin-like, -ig, a. pectinous. Pektin-korper, m. pectic substance, -s ure, /. pectic acid, -stoff, m., -substanz, /. pectio substance, -zucker, m. arabinose. pelagisch, a. pelagic. 

As investigations with polysaccharides of microbiological, plant, and animal origin revealed the presence in these substances of uronic acids, it became necessary to know more about the acids. Moreover, the occurrence of uronic acids in plant gums and pectic substances, and the structures of urinary... 

This review will focus on pectic substances that have been shown to exhibit biological activity. Their structure, bioactivity and possible structure activity relations will be discussed. 

Pectins can generally be divided into neutral and acidic polymers, but certain structural features are common between the different types of pectic substances. These will be described below. Concerning the general chemistry of carbohydrate types of linkages, the reader can find details on this in general textbooks of chemistry and biochemistry and is for this reason not included. 

From the science performed mainly over the last ten years it is obvious that the role of pectic substances in health care has been substantiated. For some of the pectic substances, parts of the structure of the bioactive sites have been determined, but further studies of the relevant structures for the individual active polymers must be performed in order to find a possible common structure for the activities observed. It also appears that there are special structural features present in some of the polymers, which are not foimd in others, and which are important for their activity, and this may explain the different behaviour of the polymers in the same system. 

Individual classes of the pectic substances will be discussed below. 

IS A GENERAL MODEL FOR PLANT CELL WALL PECTIC SUBSTANCES FEASIBLE ... 

Table 5. Suggested subunits present in most pectic substances, next to possible variations within an individual subunit.

Kauss, H., Swanson, A.L., Arnold, R., and Odzuck, W. (1969) Biosynthesis of Pectic Substances. Localization of enzymes and products in a lipid-membrane complex. Biochim.Biophys.Acta, 192 55-61. 

Stoddart, R.W. and Northcote, D.H. (1967) Metabolic relationships of the isolated fractions of the pectic substances of actively growing sycamore cells. BiochemJ. 105 45-59. 

With endogeneous pectic polysaccharides as substrates, the pectin methyhransferase activity was measured as radioactivity linked to oxalate-soluble polys x harides after extensive washing of microsomes with IM ethanolic NaCL Figure 2 shows that the rate of methylesterification of pectic substances was maximal on days 4 and 6 these maximum activities were observed within this period in at least five independent ejqjeriments. On the other hand, little activity was noted in young cells before day 2, and in old cells after day 9. In other words during the stationary phase the newly synthesised pectins remained unesterified because of the lack of pectin methyltransferase activity. 

The PGI and PGII produced from strains transformed with the promoter gene fusion are in all respects tested identical to those enzymes obtained from the wild type strain when grown on pectic substances. For both PGI and PGII the pH optimum is 4.1-4.2 in 50 mM Na-acetate buffer, 30 °C. All further kinetic analyses were performed under these conditions. 

Matsuhashi S, Inoue S-1, Hatanaka C (1992) Simultaneous measurement of the galacturonate and neutral sugar contents of pectic substances by an enzymic-HPLC method. Biosci Biotech Biochem 56 1053-1057... 

In this report we describe the kinetics of pectate and pectin degradation by Eca PL isoenzymes. Moreover, action pattern analyses using various pectic substances provide further insights into specific differences among the isoenzymes. 

The plant cell wall is a polymeric mesh consisting of cellulose, hemicellulose, pectin and protein. Cellulose and hemicellulose are integral components of the cell wall, but pectic substances are located mainly in the outer wall regions within the middle lamella (McNeil et ai, 1984). Pectic substances are more susceptible to enzymatic degradation, because they are more exposed than other cell wall components. Therefore, pectin-degrading enzymes may play a central role in the penetration of plant tissue by bacteria. 

Effect of a new canning process on cell wall pectic substances, calcium retention and texture of canned carrots... 

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