CIRCULAR-DICHROISM ANALYSIS OF LIGAND-INDUCED CONFORMATIONAL-CHANGES IN PROTEIN-KINASE-C - MECHANISM OF TRANSLOCATION OF THE ENZYME FROM THE CYTOSOL TO THE MEMBRANES AND ITS IMPLICATIONS

被引:15
作者
BOSCA, L [1 ]
MORAN, F [1 ]
机构
[1] UNIV COMPLUTENSE,FAC CIENCIAS QUIM,DEPT BIOQUIM & BIOL MOLEC,E-28040 MADRID,SPAIN
关键词
D O I
10.1042/bj2900827
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The structural changes following the binding to protein kinase C (PKC) of activators that promote its translocation to lipid environments were studied by far-u.v. c.d. and intrinsic fluorescence measurements of the protein. In the absence of activators, PKC contained 40% alpha-helix, with an average size of 13 amino acids per alpha-helix segment, and 12% beta-structure as deduced from c.d. spectral analysis while fitting a set of model proteins of known structure. Ligands that promote translocation and activation of the enzyme, such as Ca2+ ions and phorbol esters, produced drastic changes in the c.d. spectra which may be interpreted as a reduction in the average number of consecutive amino acids in the alpha-helix. Most of the total alpha-helix structure was conserved and an increase in beta-structure was produced by active phorbol esters. These activators differentially affected the fluorescence of PKC: phorbol esters shifted the emission maximum to the red, whereas Ca2+ produced a marked decrease in the intensity of the fluorescence emission, suggesting in both cases that tryptophan residues were exposed to increased polar environments after binding of the ligands.
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页码:827 / 832
页数:6
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