Có 118+ tài liệu thuộc chủ đề "nguyên tắc của hóa sinh"
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coli are encoded by a set of seven operons (Figure 30.11).. The three-dimensional struc- tures of both the 30S and 50S ribosomal subunits show that the general shapes of the ribosomal subunits are determined by the conformation of the rRNA molecules within them. Figure 30.12 illustrates the three-dimensional structure of 16S rRNA within the 30S subunit. The overall form of...
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GTP binding induces conformational changes in ribosomal components that actively engage these components in the mechanics of protein synthesis. The energy expenditure for protein synthesis is at least four high-energy phosphoric anhydride bonds per amino acid. In addition to the two provided by GTP, two from ATP are expended in amino acid activation via aminoacyl-tRNA synthesis (see Figure 30.3).. Molecular...
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(b) The base sequence of the small RNA loop within the 16S rRNA decoding center. Ribosomes with long peptidyl chains attached to the tRNA in the P site are less susceptible to macrolide antibiotics.. The first two bases of the codon and the last two bases of the anticodon form canonical Watson–Crick base pairs, but pairing between the third base...
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sine kinases, and steroid hormone receptors are some of the signal transduction mol- ecules (see Chapter 32) that must associate with Hsp90 in order to become fully com- petent. proteins fitting this description are called Hsp90 “client proteins.” The matu- ration of Hsp70 client proteins requires other proteins as well, and together with Hsp90, these proteins come together to form...
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HtrA Proteases Also Function in Protein Quality Control. DegP is lo- calized in the E. (b) In the Ubc9–RanGAP1 complex, the exposed loop of RanGAP1 lies in the binding pocket of Ubc9. Bortezomib, a small-molecule proteasome in- hibitor developed by Millenium Pharmaceuticals, Inc., has re- ceived FDA approval for the treatment of multiple myeloma, a cancer of plasma cells that...
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32.3 How Do Signal-Transducing Receptors Respond to the Hormonal Message?. All receptors that mediate transmembrane signaling processes fit into one of three receptor superfamilies (Figure 32.7):. The G-protein–coupled receptors (see Section 32.4) are integral membrane pro- teins with an extracellular recognition site for ligands and an intracellular recog- nition site for a GTP-binding protein (see following discussion).. The single-transmembrane segment...
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The v-src gene was derived from the avian proto-oncogenic gene c-src during the original formation of the virus. It undergoes two post-translational modifications: First, the amino group of the NH 2 -terminal glycine is modified by the covalent attachment of a myristoyl group (this modification is required for membrane association of the kinase. see Figure 32.20). FIGURE 32.19 The rotation...
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All possess a characteris- tic peptide domain consisting of a short -helix, a loop of 12 amino acids, and a sec- ond -helix (Figure 32.33). Robert Kretsinger at the University of Virginia initially discovered this pattern in parvalbumin, a protein first identified in the carp fish and later in neurons possessing a high firing rate and a high oxidative metabolism.....
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For example, in certain neurons in the hypothalamus, stimulation of. Metalloproteinase action releases heparin-binding EGF-like growth factor (HB-EGF) in the extracellular matrix. Binding of HB-EGF to the EGF receptor initiates a classic RTK-activated signaling pathway (Figure 32.46b).. A cell can be exposed simultaneously to multiple, potentially contradictory signals in the form of soluble hormones and ligands anchored to adjacent cells...
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These agents make postsynaptic membranes permeable to chloride ions and cause a net influx of Cl , which in turn causes hyperpolarization of the post- synaptic membrane (making the membrane potential more negative). GABA is derived by a decar- boxylation of glutamate (Figure 32.61) and appears to operate mainly in the brain, whereas glycine acts primarily in the spinal cord....
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G°(AB) 10.1 kJ/mol.. G°(BC) 17.8 kJ/mol.. G°(AC) 7.7 kJ/mol.. CrP in the amount of 135.3 moles would be required per day to provide 5860 kJ energy. G 46.1 kJ/mol.. The hexokinase reaction is a sum of the reactions for hydrolysis of ATP and phosphorylation of glucose:. 16.6 kJ/mol 12. Carbamoyl phosphate should have a somewhat larger free energy of hydrolysis...
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The horizontal and vertical coordinates of the point of intersection are 1/[B] K m A /K S A K m B and. k cat /K m 1.6 10 8 M 1 sec 1 . Because the enzyme shows maximal activity at or below 40°C, it seems more like a mammalian enzyme than a plant enzyme, which would be expected to...
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Moreover, the light-induced efflux of Mg 2 from the lumen diminishes across the thylakoid membrane, so a greater contribution of pH to the proton-motive force is warranted.. Replacement of Tyr by Phe would greatly diminish the possibil- ity of e transfer between water and P680 , limiting the ability of P680 to regain an e and return to the P680...
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This exercise is left to the student and should be based on the reference provided in the problem.. It may be presumed that the oxidation of the acyl chain is ac- complished via a two-electron transfer, whereas the steps in- volved in reoxidation of FADH 2 by ETF are one-electron transfers. The sequence of reactions involving creation of a double...
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Phosphorylation of Ser residues would lead to elec- trostatic repulsion between the DNA backbone and the histone tails. Cooperative binding of inducer would be advan- tageous, because the slope of the lac operon expression versus [inducer] would be steeper over a narrower [inducer] range.. Capping of the 5 -end and polyadenylation of the 3 -end of mRNA protect the RNA...
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See also Fatty acid synthe- sis. Branched-chain amino acid aminotrans- ferase, 793. Branched-chain fatty acid F Branched-chain -keto acid dehydrogenase. alpha-helix from, 154G structure of, 1032G. See also Glycoprotein. See also Monosaccharide. See also. proteoglycans and F, 211F, 211S, 212F. limited fixation of F, 658F. organic molecules from F, 651G, 653T, 654F, 655F in tricarboxylic acid cycle, 571–575,. -Carbonyl group,...
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N-linked, 205S structure of, 205S Glycosaminoglycan, 209 Glycosides. Gradient separation of amino acids, 86F Gram-negative bacteria, 201, 202S, 203F Gram-positive bacteria, 201, 202S, 203F,. See also Hydrogen bond. Helix behavior of amino acids, 142T Helix capping, 141F, 142. quaternary structure of, 469, 471 salt bridges between subunits of, 473F structure of, 96F, 113, 468S. subunit motion of, 472F tetrameric structure...
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The process of folding is clearly complex, but sophisticated simulations have already provided reasonable models of folding (and unfolding) pathways for many proteins (Figure 6.33). For these cases, Ken Dill has suggested that the folding process can be pictured as a funnel of free energies—an energy landscape (Figure 6.34). The rim at the top of the funnel represents the many...