Abstract:
Alliinase (EC 4.4.1.4) has been isolated from commercially available garlic
(Allium sativum L., Alliaceae) powder and was investigated
with respect to its use as ingredient of herbal remedies. The enzyme was purified
to apparent homogeneity and results were compared with those obtained from
a sample of fresh A. sativum var.
pekinense. The purification of the enzyme involved a gel filtration step
as well as affinity chromatography on concanavalin-A agarose.
V
max using L-(+)-alliin as substrate (252 μmol
min-1 mg-1) was at the lower range of data
given in the literature (214-390 μmol min-1
mg-1). L-(-)-Alliin was also accepted as
substrate (54 μmol min-1 mg-1). V
max for alliinase from
A. sativum var. pekinense was at 332 μmol
min-1 mg-1 and 90 μmol min
-1 mg-1 for L-(+)- and L-(-)-alliin,
respectively. The Kμ values for alliinase from
garlic powder were estimated to be 1.6 mM for L-(+)-alliin
and 2.8 mM for L-(-)-alliin. In contrast to literature
values, both temperature and pH optima were somewhat higher (36 °
and pH 7.0 versus 33 ° and pH 6.5, respectively). The enzyme was
found to be active in a range from pH 5 to pH 10. Gel electrophoresis gave
evidence that the alliinase obtained from garlic powder consisted of two slightly
different subunits with molecular weights of 53 and 54 kDa whereas
alliinase obtained from fresh garlic consists of two identical subunits. It
is assumed that the alliinase gets significantly altered during the drying
process of garlic powder but is still capable to convert alliin to allicin.
Key words:
Garlic -
Allium sativum var. pekinense
- Alliaceae - garlic powder - alliinase
