Pectic acids

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

Pectins are generally classed according to their ester content as high methoxyl pectins (>50% of the carboxyl groups esterified) or low methoxyl pectins (<50% of carboxyl groups esterified) (pectic acid, methyl ester [9049-34-1]). Low methoxyl pectins, like algins, require calcium for gelation. 

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. 

Schneider and Ziervogel (Ref 2) obtained nitric esters of pectin as intermediate products which were then esterified by means of acet anhydr to the corresponding acetates. In 1949, Rogovin, Treyvas and Shorygina (Ref 5) prepd pectin nitric esters by nitrating pectic acid for 4 hrs at 20° in a mixt composed of 48% HN03,... 

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. 

PDMS. See polydimethylsiloxane pectic acid, 142 pectin, 141-142 pectinic acid, 142... 

Pectin belongs to a family of plant polysaccharides in which the polymer backbone consists of (1— 4)-linked a-D-galacturonic acid repeating-units. Often, (1— 2)-linked a-L-rhamnose residues interrupt the regular polygalacturonate sequence. The high viscosity and gelling properties of pectins are exploited by the food and pharmaceutical industries. X-Ray studies on sodium pectate, calcium pectate, pectic acid, and pectinic acid (methyl ester of pectic acid) have disclosed their structural details. 

Paper ionophoresis, sugars, Maurice Stacey s work, 17 Pectic acid, 350, 352,414 Pectin, 348, 350-353 Pectinic acid, 353 Pentulose, synthesis, 281 D-cryt/iro-Pentulose 5-phosphate, 289 Peptidoglycans, 167-168 Per-O-acetylated di-D-fructose dianhydride derivatives... 

The mild-alkali-extract was digested to completion with excess EPG at room temperature for at least 48 hours. Figure 1 shows the separation of the products on a Dionex PAl ion-exchange column. The limit digest of pectic acid (nonesterified HG) by this enzyme is mono-. 

MacDonnell et al. (15) first suggested competitive displacement for the stimulation of PE activity. An increase in activity was ascribed to competitive displacement of PE from an inactive complex followed by a decline in activity at higher concentrations due to competition for carboxylic acid binding sites between PE and cations. Competitive displacement of PE from pectic acid by cations was conclusively shown with Lineweaver-Burke plots (7). The effect was moderated by pH (7, 15). We have shown that other polyamines, including putrescine, a diamine, and spermine, a tetramine, "activate PE activity similarly to inorganic cations (13). 

In the course of studies on the physicochemical properties of natural polymers in aqueous solution, attention has been drawn to pectic acid, i.e. poly (a-D)galacturonic acid as a potential model of a rigid polysaccharide. 

The length-to diameter ratio strengthens the assumption that pectic acid is a fairly rigid, rod-hke molecule and comparable to the structure of cellulose... 

The enzyme had a requirement for calcium. The addition of EDTA to the reaction mixtures, resulted in complete loss of activity, whereas the addition of CaCl2 increased the activity (figure 8). Presumably, sufficient contaminating calcium ions were present in the dialyzed enzyme and substrate mixture to permit the limited activity of the controls, but apparently these were removed by chelation with EDTA. The optimum concentration was in the range of 5 to 15 M, and higher concentration resulted in a decrease in activity. Phoma medicaginis var. pinodella synthesizes a pectin lyase that lacked an absolute requirement for calcium ions but maximum enzyme activity required the presence of 1 mM Ca [25]. The lyase from Fusarium solani f sp. phaseoli, that is active on pectin and pectic acid, is calcium-dependent [30]. Most of the pectate lyases characterized are calcium-dependent the pectate lyase from Rhizoctonia solani [34] and the endopectate lyase fi om Fusarium solani f sp. pisi [31]. 

Figure 8. Relationship of cellulose, olginic acid, and pectic acid...

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