1. IntroductionAgars, the sulfated

1. Introduction
Agars, the sulfated galactans are the most abundant structural
polysaccharide of red algal cell walls and are generally considered
as the mixture of agarose and agaropectin, and accounts for ca. 50%
of algal dry weight (Yoon & Park, 1984). These sulfated galactans
constitute a large family of hydrocolloids composed of linear chains
of galactose (Gal) with alternating-1,3 and-1,4 linkages and differ in degree and position of sulfate esterification. The agar quality
in terms of gel strength is solely attributed to the 3–6, AG content
while the sulfate moiety and the contaminating floridean starch
(storage sugars of red algae) undermine the quality of agar. In addition, presence of acidic groups such as sulfonic, pyruvic and uronic
acid in agar deteriorate its gel strength by blocking the formation
of double helices between the molecules. The proportion and distribution of the aforementioned substituents in the skeletal chain
of the galantans modify the physico-chemical properties of the
agar (Lahaye & Rochas, 1991; Yaphe & Duckworth, 1972). Among
the others, viscosity and gelling capacity are the key features that
confer diverse industrial applications for these hydrocolloids as
stabilizers, thickeners and gelling agents (Usov, 1992).
The Gal-6-sulfurylases found in agarophytes and the analogous
sulfohydrolase activities extracted from carrageenophytes represent a novel class of enzymes owing to the chemical reaction