TOWARD MODEL COMPOUNDS FOR THE ACTIVE SITE STRUCTURE OF CYTOCHROME C OXIDASE:SULFUR-BRIDGED HETEROBIMETALLIC COMPOUNDS OF COPPER(II) WITH IRON(III), COBALT(II) AND MANGANESE(II) TETRAPHENYLPORPHYRIN CENTERS

[摘要] In order to further examine the geometric and electronic properties associated with active sites in copper proteins, four new pentacoordinate model compounds,Zn('II)(imidH)(S)DAP (SO(,3)CF(,3)),Cu('II)(imidR)(S)DAP (SO(,3)CF(,3)),Zn('II)(imidR)(S)DAP (SO(,3)CF(,3)), andCu('II)(imidR)(S)DAP (SO(,3)CF(,3)) containing M-N(imidazole) and M-S (thiolate) bonds have been synthesized and characterized. Throughcomparative spectroscopic and electrochemical studies with ;;Blue;; cuproprotein centers, the new mononuclear copper(II) compounds have been found to not well mimic the electronic properties of the copper(II) active sites in the proteins. The mononuclear copper(II) compounds (and their zinc(II) counterparts) have also been reacted with ;;axially-starved;; iron(III), cobalt(II), and manganese(II) Tetra- phenylporphyrin compounds to yield a new class of twelve (mu)-thiolatobimetallic complexes as model compounds for the proposed thiolate-bridgedcyt. a(,3)('3+)-S-Cu(,U)('2+)active site structure of resting cyto- chrome c oxidase. The model compounds have been derived fromLFe('III)(TPP)(TPP('2-) = tetraphenylporphyrinato and L = SO(,3)CF(,3)('-))andM'('II)(imidH)(S)DAP (SO(,3)CF(,3)) orM'('II)(imidR)(S)DAP (SO(,3)CF(,3)) (M'('II) = Zn or Cu) to yield species containingLFe('III)-S-Zn('II)(imidH)- DAP ('+),LFe('III)-SCu('II)(imidH)DAP ('+),LFe('III)-S-Zn('II)(imidR)DAP ('+), andLFe('III)-S-Cu('II)(imidR)DAP ('+) cores. Furthermore, reaction ofM('II)(TPP)(M('II) = Co or Mn) withM'('II)(imidH)(S)DAP (SO(,3)CF(,3)) orM'('II)(imidR)(S)DAP (SO(,3)CF(,3)) (M'('II) = Zn or Cu) has produced new model compounds containingCo('II)-S-Zn('II)(imidH)DAP ('+),Co('II)-S-Cu('II)(imidH)DAP ('+),Co('II)-S-Zn('II)(imidR)DAP ('+),Co('II)-S-Cu('II)(imidR)- DAP ('+),Mn('II)-S-Zn('II)(imidH)DAP ('+),Mn('II)-S-Cu('II)(imidH)DAP ('+),Mn('II)-S-Zn('II)(imidR)DAP ('+), andMn('II)-S-Cu('II)(imidR)DAP ('+) centers as (SO(,3)CF(,3)('-)) salts. Through comparative magnetochemical and spectroscopic investigations of these novel heterobinuclear com- pounds with parallel studies on the enzyme active site, acyt. a(,3)('3+)- S-Cu(,U)('2+)active site structure for the resting enzyme has been sys- tematically tested, for the first time, by a model compound approach.

[发布机构] Rice University

[效力级别] chemistry