Plants pectins

Pectin is a long chain of pectic acid and pectinic acid molecules. Because these acids are sugars, pectin is categorized as a polysaccharide. It is prepared from citrus peels and the remains of apples after they are squeezed for juice. In the plant, pectin is the material that joins the plant cells together. When fungus enzymes break down the pectin in fruit, the fruit gets soft and mushy. 

Homology between PemA and PemB is quite low (19). Thus, it seems unlikely that the presence in E. chrysanthemi of two pern genes results firom a recent duplication of an ancestral gene as proposed for pel genes. The six regions conserved in bacterial or plant pectin methylesterases are present in PemA and PemB (19, 21). Since the central regions II, III, IV and V are more conserved than regions I and VI, they are more probable candidates to be involved in the catalytic site. 

To date only homooligogalacturonides from plant pectin have been shown to exhibit the regulatory effects. Meanwhile pectin polysaccharides consist of neutral highly branched blocks, so it was of interest to search for possible biological activity of oligomers released from such structures. 

Plant pectin heparinium Dancus carota 1GQ8 1.75 et al. (1999) Johansson... 

Johansson, K., El-Ahmad, M., Friemann, R., Jomvall, H., Markovic, O., and Eklund, H. (2002). Crystal structure of plant pectin methylesterase. FEBS Lett. 514, 243-249. 

It is proposed that the CH3C1 missing source (vide supra) may be the abiotic methylation of chloride in plants and soils (280, 281). This methylation by plant pectin in senescent and dead leaves efficiently produces CH3C1 and shows a positive correlation with temperature. Plants studied include Norway maple, horse chestnut, cherry, oak, beech, a Eucalyptus sp., and a salt marsh (Batis maritima) (281). This important study complements that of Myneni (172-174) and Keppler et al. (175,176), cited earlier, and Oberg (298, 299). 

Hamilton JTG, McRoberts WC, Keppler F, Kalin RM, Harper DB (2003) Chloride Methylation by Plant Pectin An Efficient Environmentally Significant Process. Science 301 206... 

Fungal pectin esterases have lower pH optima (ca 4.5) than plant pectin esterases (7,8) and are less heat stable (3 5,26 ). A commercially available fungal PE preparation has been introduced for industrial application in cider and lemon juice clarification (52,60). A process for the manufacture of low-ester pectins with a lower sensitivity for calcium has been patented by Ishii et al. 

D(+)-galacturonic acid. C00H(CH20)4CH0. A major constituent of plant pectins. It exhibits mu-tarotation, having both an a and a (3 form. 

Polysaccharides.—This research is centered around 1900. Many pectins were isolated from various plants gentian, red currant, and Rosa canina. Bourquelot and H issey were among the first to point out that natural macromolecules, while possessing certain general properties in common, differ nevertheless from one species to another in their degree of complexity. Plant pectins could be differentiated from one another by optical rotation, but all produced, on hydrolysis, L-arabinose and n-galac-tose. 

Bio-based materials can be obtained mainly by two different ways the direct production of polymers or the production of bio-based monomers and their further (bio)chemical polymerization. The direct production of biopolymers can be achieved by microorganisms (polyhydrojgralkanoates, PHA), by algae (alginate etc.), by superior plants (pectin etc.) or by several types of producers, e.g. cellulose is produced by superior plants but also by bacteria, chitosan is produced by crustacean but also by fungi. 

Methanol (8-11) is a member of the homologous series of saturated aliphatic alcohols found in plants in the form of various esters, most often in pectins and esters of aromatic carboxylic acids (benzoic, salicylic, cinnamic and others). Free methanol results mainly by hydrolysis of pectin catalysed by plant pectin esterases therefore, it occurs regularly in small amounts as a component of aU natural fruit juices and is present in larger amounts in wines and fruit distillates. 

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