| Isolation and Characterization of Multiple Forms of Friabilin. Journal of Cereal Science 21:167-174 |
| Morris,C.F., Greenblatt,G.A., Bettge,A.D. and Malkawi,H.I. |
| The control of endosperm texture
on wheat grain is poorly understood at the molecular level. This study reports
the isolation and partial characterization of multiple forms of friablilin a
starch granule protein associated with endosperm softness. Starch granule proteins
were isolated from water-washed wheat starch using sodium dodecyl sulfate (SDS),
NaCl, propan-2-ol or NaCl plus propan-2-ol. SDS polyacrylamide gel electrophoresis
under unreduced conditions revealed the presence of at least three components
of what we all the Mr 15k complex, i.e. starch granule proteins of
ca. Mr 15k, which have been considered previously to be single protein,
friabilin. Based on selective extraction from starch, a fourth component may
also be present. One of these four components may by as alpha-amylase inhibitor
reported previously. N-terminal amino acid sequence data suggest that major
components of the Mr 15k complex may by similar to Triton x-114-extractable
proteins, termed puroindolines, isolated from wheat flour. Members of the Mr
15k complex shared similar dehydration-denaturation characteristics based on
selective acetone precipitation. The results indicate that the operational use
of friabilin as a discrete, single protein associated with endosperm texture,
and possibly involved in texture control, must be re-evaluated. Nevertheless,
friabilin remains a useful though enigmatic, biochemical marker for grain softness.
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