P. Lechevalier et A. Vanwormhoudt, ALPHA-GLUCOSIDASE FROM THE HEPATOPANCREAS OF THE SHRIMP, PENAEUS-VANNAMEI (CRUSTACEA-DECAPODA), The Journal of experimental zoology, 280(6), 1998, pp. 384-394
Penaeus vannamei is an omnivorous species, and it can be assumed that
a high level of carbohydrates is necessary for growth. Alpha-glucosida
ses are important enzymes necessary for the ultimate liberation of glu
cose residues from various carbohydrates. Using acarbose affinity chro
matography, a glycosylated alpha-glucosidase with a molecular mass of
approximately 105 kDa was isolated for the first time from the hepatop
ancreas of the shrimp. Exhibiting an optimal catalytic activity in the
temperature range from 40 degrees C to 50 degrees C at pH 6, the puri
fied enzyme hydrolyses alpha 1-4 bonds and liberates glucose from diff
erent oligo and polysaccharides. By contrast to other known glucosidas
es, no alpha 1-6 glucose link with hydrolysis has been observed. This
could explain the different rates of growth in shrimp aquaculture with
starches from various origins. The amino-acid composition, together w
ith the partial sequence of a hydrolytic peptide, shows a high degree
of similarity to the alpha-glucosidases reported for various organisms
including yeast and fungi and may help determine the phylogeny of the
family. (C) 1998 Wiley-Liss, Inc.