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Amylase activity and inhibition from Ipomoea batatas (Caiapo) protein
Author(s) -
Peters Tiffany Beth,
Truong Van Den,
Allen Jonathan C.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a363-e
Subject(s) - amylase , ipomoea , starch , chemistry , pellet , food science , alpha amylase , biochemistry , potato starch , enzyme , botany , biology , zoology
Caiapo, an extract of sweet potato ( Ipomoea batatas ), modified the glycemic index of foods in studies suggesting Caiapo inhibits pancreatic amylase. This study aimed to determine α‐amylase inhibitory effects of sweet potato protein fractions. Proteins were precipitated from the water‐soluble fraction of sweet potato flesh with ammonium sulfate. When the precipitated protein pellet was dialyzed against water, a portion of the protein pellet redissolved and insoluble pellet remained. Both fractions were assayed for amylase and α‐amylase inhibitor activity. The samples were allowed to incubate with or without α‐amylase before starch addition. Amylase activity was calculated from absorbance of the starch solution after adding iodine. Native sweet potato amylases that were found in both insoluble and soluble protein fractions were reduced by heat treatment (97±2 and 69±5% respectively) but no heat‐stable amylase inhibition remained. Our data show native amylase activity to be greater than the amylase inhibitor activity we expected to find. Thus, a mechanism other than amylase inhibition may be responsible for the hypoglycemic effect of Caiapo. Support: NC Sweetpotato Commission