MINIATURIZED HEMOPROTEINS - DESIGN, SYNTHESIS AND CHARACTERIZATION OFMIMOCHROME-II

The present paper describes the design, synthesis and spectroscopic ch aracterization of mimochrome II, namely 3,7,12, ys(9)-Leu(10)-Lys(11)- Ile(12)-Thr(13)-Leu(14)-NH2) propionamide, and its cobalt derivative. Mimochrome II belongs to a new class of hemoprotein models, called mim ochromes. We have developed these molecules in order to investigate th e effect of protein structure and composition an modulation of the act ivity of the heme center. These molecules are composed of two helical peptide chains linked covalently to the deuteroporphyrin IX. The synth etic procedure we developed for synthesizing the prototype molecule mi mochrome I, together with the information derived from the structural characterization of the Fe(III)- and Co(III)mimochrome I complexes, en abled us to design molecules having more precise properties. By compar ing the behavior of Co(III)-mimochrome II with that of the prototype m olecule mimochrome I, we show here that the composition and folding of the peptide chains affect critically the overall structural organizat ion of the models. (C) 1998 Elsevier Science S.A. All rights reserved.