BSCI-2520 Chapter Notes - Chapter 7.1: Neuroglobin, Blood Pressure, Myoglobin
16 Sep 2016
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Tightly wedged in a hydrophobic pocket between helices e and f. A porphyrin derivative containing 4 pyrrole groups (a-d) Fe(ii) in the center is coordinated by the four porphyrin n atoms and one. N atom from a his residue (his f8) attached to myoglobin. The oxygen atom binds from above the heme group and interacts with another his residue (his e7). When oxygen is exposed to heme without the myoglobin, it binds irreversibly. This would not be useful in a biological setting. Myoglobin allows oxygen to bind reversibly to heme. Myoglobin"s main purpose is to facilitate diffusion of oxygen in muscle cells. Neuroglobin: mostly present in brain, retina, and endocrin tissues; protects neurons from damage under conditions of low oxygen (ex: stroke) Cytoglobin: present in most tissues, may have similar functions to neuroglobin. Yo2 = fractional saturation po2 = partial pressure of oxygen. Kd = dissociation constant of oxygen from myoglobin. The lower kd is, the tighter the binding.
