Hemoglobin hybrids

Hybrid Hemoglobins Verchere, Jean-Francois, Chapelle, S., Xin, F., and Crans, D. C. 47 563... 

This was attempted by Hoffman and co-workers, who studied the influence of a porphyrin vinyl group on the electron transfer rate in a [Fe, Zn] hybrid hemoglobin [149]. In this study, the chemical modification was simply achieved by preparing the hybrid with Zn deuterioporphyrin. However, entropic contributions are unknown in this system, and activation energies could not be accurately measured. Both effects preclude an accurate determination of the nuclear factor and a definitive attribution of the observed variations to the sole electronic factor. 

A photoexcited Fe VZn11 hybrid hemoglobin has been shown to have interesting electron transfer properties.11646... 

The system then returns to its initial state by back electron transfer from Fe(II)P to (ZnP)+. The decay of the TZnP triplet state is enhanced only when the p subunit contains Fe(III)P. When the j3 subunit contains Fe(II)P triplet, decay is unaffected. The rate constant of electron transfer, t, for [a(Zn)/J(Fe)] hybrid hemoglobin was found to be 102s 1 at room temperature [90]. The same value of kt was obtained for [a(Fe)/ (Zn)] hybrid hemoglobin [70]. 

Fig. 20. Temperature dependence of the electron transfer rate, kt, in the [aFe(III) p Zn] hybrid hemoglobin. Data taken from ref. 91.

Venkatesh, B., Rifkind, J. M., and Manoharan, P. T. Metal Iron Reconstituted Hybrid Hemoglobins. 47 563... 

VI. H NMR Investigations of Structures and Properties of Symmetric Valency Hybrid Hemoglobins Models for Doubly... 

Mutation in the distal heme pocket of the a chain the heme iron atoms in the a chains are in the high-spin ferric state, i.e., (a2 p2), with five unpaired electrons per heme iron in the a chains and with four unpaired electrons per heme iron in the p chains a naturally occurring valency hybrid hemoglobin... 

Symmetric Valency Hybrid Hemoglobins Models for Doubly... 

Fig. 49. 600-MHz H NMR spectra of cross-linked mixed-valency asymmetric hybrid hemoglobin (a+CNp)A(aP)cXL, in deoxy and CO forms, in the presence of 0.1 Af phosphate at pH 6.8 and 21°C. (A) Hyperfine-shifted proton resonances in D20 (B) exchangeable and hyperfine-shifted proton resonances in H20. [From Miura and Ho (1982)].

Asymmetric Hybrid Hemoglobins with One Cyanomet Heme... 

Fig. 53. Oxygen equilibrium curves of cross-linked mixed-valency hybrid hemoglobin (a + CN3)A(ap)cXL, in 0.1 M phosphate plus 2 mM KCN at various pH values. (A) Hill plots (B) 02 binding constants. [From Miura et al. (1987)].

Asymmetric Hybrid Hemoglobins with Two Cyanomet Hemes... 

Fig. 60. Representation of the 10 ligation states of hemoglobin X denotes ligation of a given chain or a metal substitution for Fe in a metal hybrid hemoglobin. Index numbers provide species designation. Subunit positions are shown in species 01. [Adapted from Ackers and Smith (1987)].

Brian M. Hoffman Electron tunneling in hybrid hemoglobins... 

Samuni U, Juszczak L, Dantsker D, Khan I, Friedman AJ, Perez-Gonzalez-de-Apodaca J, Bruno S, Hui HE, Colby JE, Karasik E, Kwiatkowski LD, MozzarelU A, Noble R, Friedman JM. Functional and spectroscopic characterization of half-Uganded iron-zinc hybrid hemoglobin evidence for conformational plasticity within the T state. Biochemistry 2003 42 8272-8288. 

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