Carbonyl-hemes

Photoexcitation of biological molecules, proteins, and enzymes also has interest (such as watching a carbonyl group photodissociate from carbonyl heme and studying the chemistry of the resulting products). 

Figure 10. Infrared spectrum of carbonyl heme A (lOmM) in bromoform with 0.13M pyridine...

The spectrum for bovine heart carbonyl heme A in pyridine-bromo-form exhibited a band at 1982 cm a second as yet unexplained weaker band was found at 2080 cm (Figure 10). In Tween 80-phosphate, the buflFer used for the oxidase, a broad band at 1976 cm was obtained for CO heme A (Figure 11). A difference spectrum for CO oxidase vs. oxidized oxidase in 1% Tween 80-0.1M potassium phosphate buffer pH 7.4 at a concentration O.lmM in heme A was obtained (Figure 12). Calcium fluoride cells, path length of 0.025 mm, maintained at 10° zb 2°C were... 

Abstract Metal-carbonyl bonds, as found for carbon monoxide either liganded to metalloporphyrins or chemisorbed onto metal surfaces, are discussed. These two classes of systems are compared with emphasis on short range vs. long range perturbations of the vibrational bands, and Vcq. It is concluded that metalloporphyrins serve as models for terminal bondi on metal surfaces and that data obtained for carbonyl-hemes enable the isolation of non-local electronic effects, which are much discussed in connection with alkali promoters coadsorbed with CO on metal catalysts. 

Key words Metal-carbonyl bonds, non-local electronic perturbations, carbonyl-hemes, chemisorbed carbon monoxide... 

In this communication I will compare the electronic structures of metal surfaces with that of metalloporphyrins and discuss the possibility of isolate non-local electronic perturbations for CO terminally bound to metal surfaces from the vibrational spectra of carbonyl-hemes. 

Cyclopentene-l-dithiocarboxylic acid, 2-amino-meta complexes, 2, 800 Cyclophane chlorophylls, 3, 58 Cyclophane hemes iron complexes, 4,1269 Cyclophosphazenes metal complexes, 2, 81 Cyclopropane carbonylation... 

The NIS investigation of heme complexes includes various forms of porphyrins (deuteroporphyrin IX, mesoporphyrin IX, protoporphyrin IX, tetraphenylpor-phyrin, octaethylporphyrin, and picket fence porphyrin) and their nitrosyl (NO) and carbonyl (CO) derivatives, and they have been the subject of a review provided by Scheidt et al. [109]. 

Table II shows the same results for the nitrosyl ferrous heme complex at Fe-NO 1.743 and 2.143 A. The singly occupied orbital (79) has primarily NO n and a character with both d and d 2 contributions. Although this orbital is deeply buried, as can be seen from its energy, it is shown between the doubly occupied and virtual orbitals for convenience. For comparison, the ground-state molecular orbitals of carbonyl-(44) and oxyheme (45) complexes are shown in Table III.

Ground-state molecular orbitals carbonyl-carbonylheme oxyheme complexes, 5,11-12t nitrosyl ferrous heme complexes, 5... 

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