ABSTRACT
TYPES OF INTERACTIONS 119
Table 4.1 Continued
Polar side chains (continued):
Tyrosine
Asparagine
Glutamine
Hydroxyproline
Potentially negatively charged side chains:
Aspartate
Glutamate
Table 4.1 Continued
Potentially negatively charged side chains (continued):
Phosphoserine
Potentially positively charged side chains:
Lysine
Arginine
Histidine
(b) Polysaccharides
Neutral polysaccharides
methylcellulose: (1-4)-linked glucose units in a linear chain
R = H or CH3
TYPES OF INTERACTIONS 121
Table 4.1 Continued
Neutral polysaccharides (continued)
dextran (glucan): α-(1-6) glycosidic linkages between glucose units; branching from α-(1-4) linkages (in some cases, α-(1-2) and α-(1-3))
starch polysaccharides: amylose, amylopectin, maltodextrins
(from acidic or enzymatic hydrolysis of starch)
amylose: α-(1-4) linearly linked glucose units
amylopectin: glucose units linked linearly via α(1-4) bonds; branching from α(1-6) bonds every 24 to 30 glucose units
Table 4.1 Continued
Neutral polysaccharides (continued)
galactomannans: (1-4)-linked -D-mannopyranose backbone; branch points (1-6)-linked -D-galactopyranose
In order of increasing mannose-to-galactose ratio:
fenugreek gum, mannose : galactose ~ 1:1 guar gum, mannose : galactose ~ 2:1 tara gum, mannose : galactose ~ 3:1 locust bean gum or carob gum, mannose : galactose ~ 4:1
Anionic polysaccharides
carboxymethylcellulose: (1-4)-linked in a linear way glucose units
R = H or CH2CO2H
TYPES OF INTERACTIONS 123
Table 4.1 Continued
Anionic polysaccharides (continued)
pectin: α-(1-4) linked D-galacturonic acid [m] with α-(1-2) linked Lrhamnose [n] (by convention, 50 % of R = CH3 for high-methoxyl
pectin, and 50 % for low-methoxyl pectin)
R = H or CH3
alginate: (1-4)-linked β-D-mannuronate and its C-5 epimer α-Lguluronate
-carrageenan and -carrageenan: repeating disaccharide residues; Residue A is (1,3-linked) D-galactose-4-sulfate; Residue B is (1,4linked) 3,6-anhydro-D-galactose for -carrageenan and (1,4-linked)
3,6-anhydro-D-galactose 2-sulfate for -carrageenan
Residue A Residue B
R = H or SO3
Table 4.1 Continued
Anionic polysaccharides (continued)
xanthan: (1-4) linked β-D-glucose backbone; side chains of mannose and glucuronic acid (side chain linked to every other glucose of backbone at the 3 position; about half terminal mannose units with pyruvic acid group linked as a ketal to its 4 and 6 positions;
other mannose unit with acetyl group at the 6 positions)
Cationic polysaccharide
acetyl-D-glucosamine (acetylated unit)
R = H or –COCH3 (acetyl)
TYPES OF INTERACTIONS 125
1. Van der Waals Interactions This is a general term to describe the universal weak long-range attractive interactions (0.4-2 kJ/mol) of electromagnetic origin exhibited by all functional groups with permanent or induced dipoles. At very short range separations (2-3 nm), of course, such attractive interactions are transformed into strong repulsion (Finkelstein and Ptitsyn, 2002).
