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PDBsum entry 1bea
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Serine protease inhibitor
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PDB id
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1bea
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References listed in PDB file
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Key reference
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Title
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Structural determinants of the bifunctional corn hageman factor inhibitor: X-Ray crystal structure at 1.95 a resolution.
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Authors
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C.A.Behnke,
V.C.Yee,
I.L.Trong,
L.C.Pedersen,
R.E.Stenkamp,
S.S.Kim,
G.R.Reeck,
D.C.Teller.
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Ref.
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Biochemistry, 1998,
37,
15277-15288.
[DOI no: ]
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PubMed id
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Abstract
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Corn Hageman factor inhibitor (CHFI) is a bifunctional 127 residue, 13.6 kDa
protein isolated from corn seeds. It inhibits mammalian trypsin and Factor XIIa
(Hageman Factor) of the contact pathway of coagulation as well as alpha-amylases
from several insect species. Among the plasma proteinases, CHFI specifically
inhibits Factor XIIa without affecting the activity of other coagulation
proteinases. We have isolated CHFI from corn and determined the crystallographic
structure at 1.95 A resolution. Additionally, we have solved the structure of
the recombinant protein produced in Escherichia coli at 2.2 A resolution. The
two proteins are essentially identical. The proteinase binding loop is in the
canonical conformation for proteinase inhibitors. In an effort to understand
alpha-amylase inhibition by members of the family of 25 cereal
trypsin/alpha-amylase inhibitors, we have made three-dimensional models of
several proteins in the family based on the CHFI coordinates and the coordinates
determined for wheat alpha-amylase inhibitor 0.19 [Oda, Y., Matsunaga, T.,
Fukuyama, K., Miyazaki, T., and Morimoto, T. (1997) Biochemistry 36,
13503-13511]. From an analysis of the models and a structure-based sequence
analysis, we propose a testable hypothesis for the regions of these proteins
which bind alpha-amylase. In the course of the investigations, we have found
that the cereal trypsin/alpha-amylase inhibitor family is evolutionarily related
to the family of nonspecific lipid-transfer proteins of plants. This is a new
addition to the group which now consists of the trypsin/alpha-amylase
inhibitors, 2S seed storage albumins, and the lipid-transfer family. Apparently,
the four-helix conformation has been a successful vehicle in plant evolution for
providing protection from predators, food for the embryo, and lipid transfer.
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