Effect of light on carbon monoxide binding by erythrocruorin

Giacometti, Giorgio M.; Focesi, Aldo; Brunori, Maurizio; Wyman, Jeffries

doi:10.1016/s0022-2836(75)80122-7

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…The most striking functional difference between Hbs and Hmcs involves the binding of CO, which in the case of Hmcs reacts with a 1:1 stoichiometry (147), since, unlike O 2 (which binds two Cu(I) atoms), CO binds only a single cuprous atom Cu(I). Thus, while in Hb or Ery the reaction with CO is associated to homotropic and heterotropic interaction phenomena which are very similar to those observed for the binding of O 2 (134,148,149), CO binding to Hmcs is noncooperative and the quaternary-linked Bohr effect is absent. Hence, the cooperative effects in Hmcs are limited to the binding of O 2 and they are strictly related to the bridging properties of this ligand which operates as a 'clamp' between the two copper atoms (Fig.…”

Section: Extracellular Giant Oxygen Carriers: Lessons On Multi-domainsupporting

confidence: 61%

Multiple strategies for O2 transport: from simplicity to complexity

et al. 2007

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SummaryO 2 carriers (extracellular and intracellular as well as monomeric and multimeric) have evolved over the last billion of years, displaying iron and copper reactive centers; very different O 2 carriers may coexist in the same organism. Circulating O 2 carriers, faced to the external environment, are responsible for maintaining an adequate delivery of O 2 to tissues and organs almost independently of the environmental O 2 partial pressure. Then, intracellular globins facilitate O 2 transfer to mitochondria sustaining cellular respiration. Here, molecular aspects of multiple strategies evolved for O 2 transport and delivery are examined, from the simplest myoglobin to the most complex giant O 2 carriers and the red blood cell, mostly focusing on the aspects which have been mainly addressed by the so called 'Rome Group'.

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Section: Extracellular Giant Oxygen Carriers: Lessons On Multi-domainsupporting

confidence: 61%

Multiple strategies for O2 transport: from simplicity to complexity

et al. 2007

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“…[1], which holds for the simple case of myoglobin, applies also to erythrocruorin, we should expect the slope of the curve in Fig. 5 to give, at any point, the photochemical efficiency w. It is suggestive that the change of slope on the final saturation with CO (also given in the figure) does in fact correspond to the previous observation that the quantum yield for CO depends on the initial saturation, passing through a maximum in the middle range.…”

supporting

confidence: 68%

“…This is what would in a general way be expected. Thus, in the simple case of myoglobin, it is confirmed that IT = l+wI+l'(CO+Fe++) [1] where I is light intensity and w represents photochemical efficiency. In strong light, therefore, 1/i approaches W I.…”

mentioning

confidence: 82%

“…On the other hand, when Y < 1 and free CO is present at lower concentration, the ligand concentration will vary during the relaxation process and the underlying assumption that the X's in Eq. [1] ,. 0 -I-I under these conditions is insensitive to the intensity of the flash (i.e., to the amount of ligand driven off) would imply that there is no great difference in quantum yield between the sites in the fast and slow constellations.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Kinetics of binding of carbon monoxide to lumbricus erythrocruorin: a possible model.

Giacometti¹,

Focesi²,

Giardina³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

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This paper represents a kinetic study of the binding of carbon monoxide by Lumbricus erythrocruorin. Observations on the quantum yield and the relaxation of the system both to equilibrium and to the steady state realized in the presence of constant illumination under various conditions are reported. The The results of the earlier paper (1), which represent an essentially static approach to the problem, may be summarized as follows:(i) The spectral measurements show the absence of any exact isosbestic points in the binding of CO to deoxyerythrocruorin such as would be expected in the case of a simple process.(ii) The shape of the binding curve (or Hill plot) is profoundly modified under the steady-state conditions produced by the stationary light, the cooperativity being reduced.(Mi) The quantum yield, as determined by the "pulse method," varies, though not greatly, with the saturation of the molecule with CO, passing through a maximum in the middle range of saturations. All these observations were shown to be phenomenologically consistent.The present study, which represents a kinetic approach to the same problem, describes observations on the quantum yield and the relaxation of the system both to the steady state and to equilibrium under various conditions. MATERIALS AND METHODS Earthworm erythrocruorin was prepared as previously described (3) Fig. 1. From an analysis of the data it appears that in case a the reaction was about 70% slow, with 1' = (1.9 4 0.6) X 105 M-1 sec-1, and 30% fast with 1' = (1.4 I 0.4) X 106. In case b, where the process was all fast, 1' = 1.5 X 106 M-1 sec-1, the same as in case a. 2. Action spectra Action spectra for the fast and slow phases of the reaction calculated from the oscillograph traces under conditions a are shown in Fig. 2 and are consistent with the lack of a true isosbestic point reported earlier (1). From Fig. 2 it is clear that the determination of the relative amounts of fast and slow components must depend on the observation wavelength. The figures, 70 and 30%, given above were based on measurements far removed from the point of crossing of the curves in Fig. 2. It was found that if the intensity of the flash was gradually decreased so that only partial dissociation was achieved, the results, both as to the relative amounts of the two components and their rate constants, were unaffected.

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“…This competitive inhibition of O 2 binding is the reason CO is a poisonous gas. LtEc can also bind CO and its subunits appear to have varying affinities (either high or low) for CO [ 58 , 59 ].…”

Section: Interactions Between Ltec and Other Ligandsmentioning

confidence: 99%

Biophysical Properties of Lumbricus terrestris Erythrocruorin and Its Potential Use as a Red Blood Cell Substitute

Elmer

Palmer

2012

JFB

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Previous generations of hemoglobin (Hb)-based oxygen carriers (HBOCs) have been plagued by key biophysical limitations that result in severe side-effects once transfused in vivo, including protein instability, high heme oxidation rates, and nitric oxide (NO) scavenging. All of these problems emerge after mammalian Hbs are removed from red blood cells (RBCs) and used for HBOC synthesis/formulation. Therefore, extracellular Hbs (erythrocruorins) from organisms which lack RBCs might serve as better HBOCs. This review focuses on the erythrocruorin of Lumbricus terrestris (LtEc), which has been shown to be extremely stable, resistant to oxidation, and may interact with NO differently than mammalian Hbs. All of these beneficial properties show that LtEc is a promising new HBOC which warrants further investigation.

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Effect of light on carbon monoxide binding by erythrocruorin

Cited by 7 publications

References 12 publications

Multiple strategies for O2 transport: from simplicity to complexity

Multiple strategies for O2 transport: from simplicity to complexity

Kinetics of binding of carbon monoxide to lumbricus erythrocruorin: a possible model.

Biophysical Properties of Lumbricus terrestris Erythrocruorin and Its Potential Use as a Red Blood Cell Substitute

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