Conformational analysis of PKI(5-22)amide, the active inhibitory fragment of the inhibitor protein of the cyclic AMP-dependent protein kinase. |
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| Authors: | J Reed J S De Ropp J Trewhella D B Glass W K Liddle E M Bradbury V Kinzel and D A Walsh |
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| Institution: | Institute of Experimental Pathology, German Cancer Research Center, Heidelberg, Federal Republic of Germany. |
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| Abstract: | Fourier-transform i.r. spectroscopy, 1H-n.m.r. spectroscopy and X-ray scattering were used to study the conformation and shape of the peptide PKI(5-22)amide, which contains the active site of the inhibitor protein of the cyclic AMP-dependent protein kinase Cheng, Van Pattern, Smith & Walsh (1985) Biochem. J. 231, 655-661]. The X-ray-scattering solution studies show that the peptide has a compact structure with Rg 0.9 nm (9.0 A) and a linear maximum dimension of 2.5 nm (25A). Compatible with this, Fourier-transform i.r. and n.m.r. determinations indicate that the peptide contains approx. 26% alpha-helix located in the N-terminal one-third of the molecule. This region contains the phenylalanine residue that is one essential recognition determinant for high-affinity binding to the protein kinase catalytic site. |
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