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Title
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Nuclear magnetic resonance solution and X-ray structures of squash trypsin inhibitor exhibit the same conformation of the proteinase binding loop.
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Authors
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T.A.Holak,
W.Bode,
R.Huber,
J.Otlewski,
T.Wilusz.
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Ref.
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J Mol Biol, 1989,
210,
649-654.
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PubMed id
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Abstract
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A comparison of the solution nuclear magnetic resonance (n.m.r.) structures of
squash trypsin inhibitor from seeds of the squash Cucurbita maxima with the
X-ray structure of a trypsin complex of the inhibitor shows that the n.m.r. and
X-ray structures are similar in terms of the global folding and secondary
structure. The average atomic root-mean-square difference between the 36 n.m.r.
structures on the one hand and the X-ray structure is 0.96 A for the backbone
atoms and 1.95 A for all heavy atoms. The n.m.r. and X-ray structures exhibit
extremely similar conformations of the primary proteinase binding loop. Despite
the overall similarity, there are small differences between the mean computed
structure and the X-ray structure. The n.m.r. structures have slightly different
positions of the segments from residues 16 to 18, and 24 and 25. The n.m.r.
results show that the inclusion of stereospecific assignments and precise
distance constraints results in a significant improvement in the definition of
the n.m.r. structure, making possible a detailed analysis of the local
conformations in the protein.
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