User:Sivakami Sambasivam

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Contents

Hemoglobin CO filter

Research Problem

As many of us have learned in 7.05, hemoglobin is a very essential protein in our body. It transports oxygen throughout our body. Though its affinity for O2 is fairly high, its affinity for carbon monoxide is 200x higher. Thus oxygen is easily replaced by carbon monoxide in hemoglobin. In the body, this basically inhibits a person's ability to transport oxygen at all-all the body's hemoglobin is bound to carbon monoxide instead. This competitive inhibition is so high that, a CO concentration of only 35 ppm will cause headaches and dizziness with 6 hours of exposure. A concentration of 1600ppm will leave you insensible. Common sources of CO include cars (especially race cars), cigarettes, and regular fires. Because of carbon monoxide's high toxicity, there have been created CO filters, to be placed in race-car drivers helmets, to protect fuels, and in masks that firefighters use. These filters remove the CO from the air, some of which converting the CO to CO2. However, how well do these filters bind the CO and remove it from the air? Is it as good as hemoglobin? (Not sure yet, but we believe not.)


So what if we could use hemoglobin? They've discovered a way to create fibrous mats of pure hemoglobin using electrospinning. So maybe we could use these mats of hemoglobin in a filter-the hemoglobin would bind the CO, removing it from the air coming through.


This is the ultimate goal of our research. However, there is an important question that must be addressed first: how would we know when the hemoglobin filter is at capacity? A.k.a, how would we know when the mat is filled with CO and can no longer bind anymore? Maybe we could use fluorescence. A mat that fluoresced when bound by CO would give the ability to visualize the saturation of CO. Once at a certain level of fluorescence, a.k.a. at a certain saturation, the filter would be changed out for a new one.


Experimental Question

We know that there can be fluorescence induced in hemoglobin. HPT, for example, is a fluorescent marker that loses its fluorescence as it binds hemoglobin, then gains it back as it is displaced by CO. So, a HPT-doped hemoglobin would fluoresce brightly when saturated with CO. We know this fluorescence works with hemoglobin solution. But will it still work in a dry mat of hemoglobin? Can we still induce fluorescence the same way, even outside of a solution? If not, will it work if the mat is sitting in solution?

Additional questions/way to test them

  • We will need to check if HPT can fluoresce outside of solution, so we will need to analyze how HPT works and then come up with a prediction and test this.
  • We will also need to check if HPT can still bind to a hemoglobin mat. Thus we will need to see if the hemoglobin mat causes conformational changes in the hemoglobin which would prevent the hemoglobin from binding hpt.
  • We will need to see if the hemoglobin mats bind CO at the same efficacy that normal hemoglobin binds the mats.
  • Finally, we will need to test if the fluoresence is brighter in a solution or in dry air, and we will need to ensure that the hemoglobin mats are sturdy and non-degradable in both situations.

Other considerations

  • cost efficiency
  • performance compared to current technology
  • waste/removal procedures
    • effects of waste of environment
  • how big of a filter do you need to make?


=====Below is a Way for us to create a control for the amount of HPT that we dope it with?=====

"A fluorescent analogue of diphosphoglycerate (DPG), hydroxy-pyrenetrisulfonate (HPT), was used as a probe of the allosteric equilibrium of methemoglobin. Like DPG, HPT binds, one per tetramer, with a higher affinity to deoxyHb than to oxyHb. Once bound, the HPT fluorescence is quenched by energy transfer to the hemes. HPT can thus serve as a probe of the conformational state of the hemoglobin tetramer: a higher quenching indicates a stronger binding and therefore, more of the deoxy conformation. Since HPT binds to the same site as DPG, it can be displaced by DPG in order to determine the fluorescence intensity of the free HPT under the same conditions, to correct for the inner filter effect. The high spin ferric ligands, such as water and F, showed less fluorescence (more of the deoxy state) than low spin cyano-metHb. The aquo-metHb samples showed a reversion to the oxyHb conformation above pH 7, as expected due to the acid–alkaline transition forming hydroxy-metHb. Effectors such as bezafibrate, which do not bind to the same site as DPG, show an increase in the deoxy-like characteristics."


Potential problems

So, the hemoglobin mats are a completely new technology...will we have trouble completing this research project because of that? Will we have to hypothesize information about their interactions by figuring out what their interactions with the mats are?

Research done

Source 1

They have successfully created fibers of hemoglobin and myoglobin. These fibers were spun into mats, basically creating grafts of pure hemogoblin/myoglobin. The fibers were made by electrospinning hemoglobin/myoglobin solutions. The concentration of the solutions determined the thickness and width. They hope to use these mats as dressings for wounds, enabling the wound to heal faster since there would be a direct transport of oxygen to the site. They want to test and make sure they can create these mats and have them still be able to transport oxygen-they haven’t tested that yet. C.P. Barnes et al., Feasibility of electrospinning the globular proteins hemoglobin and myoglobin, J Eng Fibers Fabrics 1 (2) (2006), pp. 16–29.

Source 2

http://www.jbc.org/cgi/reprint/246/18/5832

    • Paper describing HPT reporting of CO binding

Use of a Fluorescent Analogue of 2,3- Diphosphoglycerate as a Probe of Human Hemoglobin Conformation during Carbon Monoxide Binding*

The paper found that HPT bound to hemoglobin and that when it did, its fluoresence was quenched. It found that CO displaced HPT at a rate of about 3 CO binding for every one HPT displaced. This was with normal hemoglobin. They used HPT as sort of an analogue for the physiologically important phosphates, and the HPT was used at low concentrations relative t the hemoglobin. They did this so that they would not disturb the function of hemoglobin and so that they could observe the maximum fluoresence change during CO binding. CO binding was uninfluenced by the HPT bound to the hemoglobin.

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