(b) The hemoglobin subunits expressed in a growing fetus and adult mother are different from each other. Thefetal y variant of the adult ß subunit substitutes a Ser for one of the His residues that interacts with BPG in thecentral cavity between the ß subunits, reducing affinity for BPG.(i) Draw in oxygen binding curves below for the wild-type adult hemoglobin and the fetal hemoglobincontaining the y variant. Make sure to label each curve.Fractional occupancy (f)1.0₁0.5-tissuesT50po₂ (torr)2lungs100(ii) Given how the mutation influences BPG binding, why do you think its advantageous for the fetus tocarry this amino acid substitution? Provide a mechanistic explanation for your answer. The image below depicts 2,3-bisphosphoglyceratedepicted in dark gray, and ß subunits are depicted in light gray.(BPG) bound to hemoglobin. The a subunits areBPG

Hemoglobin is a globular protein, ie it is roughly spherical. It is a tetramer of two types of…

Answered: (b) The hemoglobin subunits expressed…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Based on the following data, is the p50 higher or lower than normal in (a) hemoglobin Yakima and (b) hemoglobin Kansas? Explain. Name Yakima Kansas Mutation Asp G1 (99) ẞ → His Asn G4 (102) ß → Thr Effect Disrupts a hydrogen bond that stabilizes the T conformation Disrupts a hydrogen bond that stabilizes the R conformation
5. (a) Hexokinase IV is known as glucokinase (GCK) and is a central metabolic enzyme that participates in glucose homeostatic maintenance by governing the rates of glucose catabolism in pan- creatic B-cells and glycogen storage in hepatocytes (liver cells). In contrast to the regulatory mecha- nisms of hexokinase I or Il in other tissues, GCk is regulated by binding to the Glucokinase Regulatory Protein (GRP) located in the cell nucleus. When glucose in hepatocytes is low, GCK is sequestered in the nucleus by binding to the GRP. High glucose, for instance, after ingestion of a meal, disrupts the GRP-GCK complex, allowing the GCK to diffuse into the cytoplasm to convert glucose into glucose-6- phosphate. Contrast the properties of hexokinases I and IV with respect to oligomeric structure, mech- anism of regulation of their activity, KM value, and dependence of catalytic activity on cellular location. Hexokinase l is found in, for instance, muscle tissue. Property subunit structutre…
Oxygen affinity of fetal blood is higher than that of maternal blood and may help to provide the fetus with an adequate oxygen supply during pregnancy. In mammals, 2, 3-biphosphosphoglycerate (BPG) mediates intracellular hemoglobin function by lowering cxygen affinity. Fetal red blood cells have higher affinity for oxygen because of a smaller effect of BPG on oxygen affinity of fetal hemoglobin (Hb F) compared with adult Hb (Hb A). Which symbol shows the PS0 value corresponding to Hb F? 14 12 10 0.0 0.5 1.0 1.5 2.0 2,3-BPG (mM) O Crcle O Dimond O Square O Triangle (6H ww) d
. What physiological effect would you predict from a mutation that replaced with serine the cysteine in the constant part of the immunoglobulin light chain that is involved in disulfide-bond for- mation with the heavy chain? ,
Of all the genes in the human genome, the ones withthe most characterized Alu insertions are those thatcause hemophilia, including several insertions in thefactor VIII and factor IX genes. Based on this fact, yourcolleague hypothesizes that the Alu element prefers toinsert into these genes. Do you agree? What other reason can you provide that also explains these data?
A) 43 14 When Friend erythroleukemic cells are incubated with sodium butyrate, they differentiate into nondividing, hemoglobin-synthesizing cells. Butyrate-induced differentiation is accompanied by accumulation of acety- lated forms of H3 and H4 histones, as can be seen most clearly for H4 in Fig- ure 4-16A. In principle, butyrate treatment could increase the activity of his- tone acetyl transferases (HATS) or decrease the activity of histone deacety- lase complexes (HDACs). To distinguish between these alternatives, HAT and HDAC activities were measured in the presence and absence of butyrate (Figure 4-16B and C). From these results decide how butyrate treatment causes accumulation of acetylated histones. butyrate (B) H-acetylated histone (cpm, thousands) N -butyrate + butyrate boiled 9 30 10 20 time (minutes) (C) C free 'H-acetate (cpm, thousands) S43210 boiled -butyrate +butyrate,
The activity provides you with a version of the NGF pathway, an example of a RTK. All of the proteins involved can be in ON/OFF states. Using this cell signaling pathway you will be asked a variety of questions to determine how the molecules are regulated, but also how a cell would respond if this cell signaling party steps were interrupted or activated. Neural Growth Factir (NGF) Ras- Ras- GDP GTP Trk-A Ras-GEF braf braf МЕК МЕК ERK ERK ERK ERK STAT STAT Spiouty DNA Nucleus Cytosol
How does the difference between the-chain and the -chain of hemoglobin explain the differences inoxygen binding between Hb A and Hb F?
The hemoglobin in the fetus (HbF) is a structural variant of the hemoglobin in the mother (HbA). HbA is a tetrameric protein complex consisting of two α-globin and two β-globin subunits. HbF is made up of two αglobin and two γ-globin subunits, where the γ-globins are similar to the β-globins but γglobins have lower affinity for 2,3- bisphosphoglycerate or BPG. Studies of oxygen transport in pregnant mammals show that the oxygen-saturation curves between the red blood cells of the fetus and the mother are markedly different. 1. The shape of hemoglobin binding curves is: hyperbolic or sigmoidal 2. a) Based on the binding curves, determine the dissociation constant (Kd) for each hemoglobin complex. (Show correct units.) Kd of HbF + BPG: ________________ Kd of HbA + BPG: _____________________ b) Which has a higher affinity for oxygen? HbF+BPG HbA+BPG 3. a) How many BPG molecule(s) is/are expected to bind one hemoglobin complex? 1 2 3 4 b) BPG binding preferentially stabilizes which state…
Fetal hemoglobin binds to BPG to a lesser extent than does HbA because His 143 in the BPG binding pocket in β-globin has been replaced with a serine residue in γ-globin. As a result of the loss of two positive charges (one for each of two γ-globins), the binding pocket binds BPG less avidly. What are the consequences of this phenomenon for mother and fetus?
What is the role of 2, 3-Bisphosphoglycerate (2,3-BPG) in the function of haemoglobin as an oxygen carrier molecule? Explain the binding mechanism and effect of 2,3-BPG leading to the reduced oxygen binding affinity for haemoglobin and transitions in the T (deoxygenated) and R (oxygenated) states of haemoglobin.
Studies of oxygen transport in pregnant mammals show that the O2-saturation curves of fetal and maternal blood are markedly different when measured under the same conditions. Fetal erythrocytes contain astructural variant of hemoglobin, HbF, consisting of two α and two γ subunits (α2 γ2 ), whereas maternal erythrocytes contain HbA (α2β2).(a) Which hemoglobin has a higher affinity for oxygen under physiological conditions, HbA or HbF? Explain.(b) What is the physiological significance of the different O2 affinities?(c) When all the BPG is carefully removed from samples of HbA and HbF, the measured O2 -saturation curves (and consequently the O2 affinities) are displaced to the left. However, HbA now has a greater affinity for oxygen than does HbF. When BPG is reintroduced, the O2 -saturation curves return to normal, as shown in the graph. What is the effect of BPG on the O2 affinity of hemoglobin? How can the above information be used to explain the different O2 affinities of fetal and…

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