Hence RLL may be used in carbohydra

Hence RLL may be used in carbohydrate banding research and the
production of immobilized lectins for affinity chromatography.
The lectin was stable up to 701C. The hemagglutinating
activity was reduced to 50% when the temperature was elevated
to 801C. No hemagglutinating activity was detected when the
temperature was or above 901C(Table 4). The hemagglutinating
activity was retained in the presence of 6 mM and 12.5 mM
solutions of NaOH or HCl, but was reduced to 25% when the
molarity of the acid or alkali was increased to 25 mM. The
hemagglutinating activity disappeared altogether in 100 mM
NaOH and HCl solutions (Table 5). It is more thermostable than
some mushroom hemagglutinatins, such as those from
Schizophyllum commune (Han et al., 2005) and Pleurotus
ostreatus (Wang et al., 2000), which are stable at and below
401C, respectively. The thermostability of RLL is very similar to
that ofArmillaria luteo-virenslectin which is stable up to 701C but
inactivated at 801C and 901C(Feng et al., 2006). Comparisons of
pH and temperature stability of R. lepida lectin and other
mushroom lectins was showed inTable 3.
The hemagglutinating activity of the lectin was unaffected by
the presence of Ca
2+
,Mg
2+
,Zn
2+
,Fe
2+
,Al
3+
, and Fe
3+
ions. It was
increased by Cu
2+
, but decreased by Co
2+
,Mn
2+
, and Hg
2+
ions
(Table 6). It is noteworthy that Cu
2+
ions augment the
hemagglutinating activity of R. lepida lectin. Dolichos biflorus
lectin possesses bound Cu
2+
ions which, however, are not related
to its sugar binding activity (Borrebaeck et al., 1981). The activity
ofR. lepidalectin is not affectied by Fe
2+
,Fe
3+
and Al
3+
ions. In
contrast, Fe
3+
and Al
3+
ions are important to the hemagglutinating activity ofBoletus edulislectin (Zheng et al., 2007).
The hemagglutinating activity of RLL is inhibited by Mn
2+
,Co
2+
and Hg
2+
ions. By comparison, the hemagglutinating activity of
Boletus edulis(Zheng et al., 2007) and Schizophyllum commune
(Han et al., 2005) lectins are also depressed by Mn
2+
ions.
RLL inhibited the proliferation of Hep G2 and MCF-7
tumor cells with an IC50value of 1.6mM and 0.9mM, respectively
(Fig. 4), with a higher potency than French bean lectin (Lam and
Ng, 2009). Daily intraperitoneal injections of the lectin (5.0 mg/kg
body weight/day for 20 days) brought about 67.6 % reduction in
weight of S-180 tumor (Table 7). RLL exhibited a weaker
antitumor potency thanPleurotus citrinopileatuslectin (Li et al.,
2008) which had the same molecular weight (Table 6) The lectin
lacked anti HIV-1 RT, antifungal, and ribonuclease activities when
tested up to 100mM (data not shown).
RLL manifested potent antitumor activityin vivo and vitro.
Previously, the antiproliferative effect of lectins on tumor cell
lines and the antitumor action of lectins in tumor-bearing mice
have been demonstrated usingAgaricus bisporuslectin (Wang
et al., 1998;Yu et al., 1993),Pleurotus ostreatuslectin (Wang et al.,