FOLDING OF APOMINIMYOGLOBIN

被引:29
作者
DESANCTIS, G
ASCOLI, F
BRUNORI, M
机构
[1] UNIV ROMA LA SAPIENZA,DIPARTIMENTO SCI BIOCHIM ALESSANDRO ROSSI FANELLI,I-00185 ROME,ITALY
[2] UNIV ROMA LA SAPIENZA,CNR,CTR BIOL MOLEC,I-00185 ROME,ITALY
[3] UNIV CAMERINO,DIPARTIMENTO BIOL MOLEC CELLULARE & ANIM,I-62032 CAMERINO,ITALY
[4] UNIV ROMA TOR VERGATA,DIPARTIMENTO MED SPERIMENTALE & SCI BIOCHIM,I-00173 ROME,ITALY
关键词
PROTEIN FOLDING INTERMEDIATES; CIRCULAR DICHROISM;
D O I
10.1073/pnas.91.24.11507
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The acid unfolding pathway of apominimyoglobin (ape-mini-Mb), a 108-aa fragment (aa 32-139) of horse heart apomyoglobin has been studied by means of circular dichroism, in comparison with the native apoprotein. Similar to sperm whale apomyoglobin [Hughson, F. M., Wright, P. E. and Baldwin, R. L. (1990) Science 249, 1544-1548], a partly folded intermediate (alpha-helical content approximate to 35%) is populated at pH 4.2 for horse heart apomyoglobin. For this intermediate, Hughson ct al. proposed a structural model with a compact subdomain involving tertiary interactions between the folded A, G, and H helices, with the,remainder of the protein essentially unfolded. As described in this paper, a folding intermediate with an alpha-helical content of approximate to 33% is populated at pH 4.3-5.0 also in ape-mini-Mb. The add unfolding path way is similarly affected in both the native and the mini apoprotein by 15% trifluoroethanol, a helix-stabilizing compound. Thus, the folding of the apo-mini-Mb intermediate is similar to that observed for the native apoprotein, in spite of the absence in the miniprotein of the A helix and of a large part of the H helix, which are crucial for the stability of apo-Mp intermediate. Our results suggest that acquisition of a folded state in apo-mini-Mb occurs through an alternative pathway, which may or may not be shared also by apo-Mb.
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页码:11507 / 11511
页数:5
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