O Hmi
A family of novel extended ribbon structures that bind metal ions, particularly calcium, in their structure are the alginate polysaccharides of marine brown algae Phaeophyceae . These include poly -d-mannuronate and poly a-l-guluronate , which are 1n4 linked chains formed from 3-mannuronic acid and a-L-guluronic acid, respectively. Both of these homopolymers are found together in most marine alginates, although to widely differing extents, and mixed chains containing both monomer units are also...
Info Lnv
FIGURE 8.2 Structures of two unusual fatty acids lactobacillic acid, a fatty acid containing a cyclopropane ring, and tuberculostearic acid, a branched-chain fatty acid. prostaglandins, a class of compounds that exert hormone-like effects in many physiological processes discussed in Chapter 25 . In addition to unsaturated fatty acids, several other modified fatty acids are found in nature. Microorganisms, for example, often contain branched-chain fatty acids, such as tuberculostearic acid...
Info Wed
FIGURE 8.1 The structures of some typical fatty acids. Note that most natural fatty acids contain an even number of carbon atoms and that the double bonds are nearly always cis and rarely conjugated. FIGURE 8.1 The structures of some typical fatty acids. Note that most natural fatty acids contain an even number of carbon atoms and that the double bonds are nearly always cis and rarely conjugated. is oleic acid, or 18 1 9 , with the number in parentheses indicating that the double bond is...
Example
What is the pH of a 0.1 M solution of acetic acid Or, to restate the question, what is the final pH when 0.1 mol of acetic acid HAc is added to water and the volume of the solution is adjusted to equal 1 L The dissociation of HAc in water can be written simply as where Ac- represents the acetate ion, CH3CQQ-. In solution, some amount x of HAc dissociates, generating x amount of Ac- and an equal amount x of H . Ionic equilibria characteristically are established very rapidly. At equilibrium, the...
Exterminator ProteinsBiological Pest Control at the
Control of biological pests, including mosquitoes, houseflies, gnats, and tree-consuming predators like the eastern tent caterpillar, is frequently achieved through the use of microbial membrane proteins. For example, several varieties of Bacillus thu-rigiensis produce proteins that bind to cell membranes in the digestive systems of insects that consume them, creating transmembrane ion channels. Leakage of Na , K , and H ions through these membranes in the insect gut destroys crucial ion...
HendersonHasselbalch Equation
Consider the ionization of some weak acid, HA, occurring with an acid dissociation constant, Ka. Then, Rearranging this expression in terms of the parameter of interest, H , we have Taking the logarithm of both sides gives If we change the signs and define pKa -log Ka, we have This relationship is known as the Henderson-Hasselbalch equation. Thus, the pH of a solution can be calculated, provided Ka and the concentrations of the weak acid HA and its conjugate base A- are known. Note particularly...
Fischer Projection Formulas
In a similar manner, ketones can react with alcohols to form hemiketals. The analogous intramolecular reaction of a ketose sugar such as fructose yields a cyclic hemiketal Figure 7.6 . The five-membered ring thus formed is reminiscent of furan and is referred to as a furanose. The cyclic pyranose and fura-nose forms are the preferred structures for monosaccharides in aqueous solution. At equilibrium, the linear aldehyde or ketone structure is only a minor component of the mixture generally much...
Selectins Rolling Leukocytes and the Inflammatory Response
Human bodies are constantly exposed to a plethora of bacteria, viruses, and other inflammatory substances. To combat these infectious and toxic agents, the body has developed a carefully regulated inflammatory response system. Part of that response is the orderly migration of leukocytes to sites of inflammation. Leukocytes literally roll along the vascular wall and into the tissue site of inflammation. This rolling movement is mediated by reversible adhesive interactions between the leukocytes...
Look Ind
Polar Bears Use Triacylglycerols to Survive Long Periods of Fasting The polar bear is magnificently adapted to thrive in its harsh Arctic environment. Research by Malcolm Ramsey at the University of Saskatchewan in Canada and others has shown that polar bears eat only during a few weeks out of the year and then fast for periods of 8 months or more, consuming no food or water during that time. Eating mainly in the winter, the adult polar bear feeds almost exclusively on seal blubber largely...
R
three forms as Gly , Gly0, and Gly- , we can write the first dissociation of Gly as Values for K1 for the common amino acids are typically 0.4 to 1.0 X 10 2 M, so that typical values of pK1 center on values of 2.0 to 2.4 see Table 4.1 . In a similar manner, we can write the second dissociation reaction as p a Values of Common Amino Acids
Proteoglycans
Proteoglycans are a family of glycoproteins whose carbohydrate moieties are predominantly glycosaminoglycans. The structures of only a few proteoglycans are known, and even these few display considerable diversity Figure 9.31 . They range in size from serglycin, having 104 amino acid residues 10.2 kD to versican, having 2409 residues 265 kD . Each of these proteoglycans contains one or two types of covalently linked glycosaminoglycans Table 9.2 . In the known proteoglycans, the...
Terpenes
The terpenes are a class of lipids formed from combinations of two or more molecules of 2-methyl-1,3-butadiene, better known as isoprene a five-carbon unit that is abbreviated C5 . A monoterpene C10 consists of two isoprene units, a sesquiterpene C15 consists of three isoprene units, a diterpene C20 has four isoprene units, and so on. Isoprene units can be linked in terpenes to form straight chain or cyclic molecules, and the usual method of linking isoprene units is head to tail Figure 8.16 ....
Coo
ties of the red cell. This extracellular portion of the protein also serves as the receptor for the influenza virus. Glycophorin has a total molecular weight of about 31,000 and is approximately 40 protein and 60 carbohydrate. The glycophorin primary structure consists of a segment of 19 hydrophobic amino acid residues with a short hydrophilic sequence on one end and a longer hydrophilic sequence on the other end. The 19-residue sequence is just the right length to span the cell membrane if it...
Further Reading 1
Beynon, R. J., and Easterby, J. S., 1996. Buffer Solutions The Basics. New York IRL Press Oxford University Press. Cooper, T. G., 1977. The Tools of Biochemistry, Chap. 1. New York John Wiley amp Sons. Darvey, I. G., and Ralston, G. B., 1993. Titration curves misshapen or mislabeled Trends in Biochemical Sciences 18 69-71. Edsall, J. T., and Wyman, J., 1958. Carbon dioxide and carbonic acid, in Biophysical Chemistry, Vol. 1, Chap. 10. New Ybrk Academic Press. Franks, F., ed., 1982. The...
H Tpk
appear to function by interacting with a variety of other molecules through their glycosaminoglycan components and through specific receptor domains in the polypeptide itself. For example, syndecan from the Greek syndein meaning to bind together is a transmembrane proteoglycan that associates intra-cellularly with the actin cytoskeleton Chapter 17 . Outside the cell, it interacts with fibronectin, an extracellular protein that binds to several cell surface proteins and to components of the...
H H
d. Chymotrypsin treatment gave two tripeptides and a dipeptide. Acid hydrolysis of the dipeptide yielded only Gly. e. Cyanogen bromide treatment yielded two tetrapeptides. f. Clostripain treatment gave a pentapeptide and a tripeptide. What is the amino acid sequence of this octapeptide 9. Amino acid analysis of an oligopeptide containing nine residues revealed the presence of the following amino acids Arg Cys Gly Leu Met Pro Tyr Val The following was found a. Carboxypeptidase A treatment...
N 1
What is the amino acid sequence of this decapeptide 5. Analysis of the blood of a catatonic football fan revealed large concentrations of a psychotoxic octapeptide. Amino acid analysis of this octapeptide gave the following results 2 Ala 1 Arg 1 Asp 1 Met 2 Tyr 1 Val 1 NH4 The following facts were observed a. Partial acid hydrolysis of the octapeptide yielded a dipeptide of the structure
Predicted
Actual and predicted structures of three domains of intestinal fatty acid binding protein Actual and predicted structures of an a-helical domain of cytochrome b562 FIGURE 6.40 A comparison of the structures of four protein domains and predictions of these structures by the program LINUS by Rose and Srinivasan. Professor George Rose Johns Hopkins University 6.5 Subunit Interactions and Quaternary Structure Many proteins exist in nature as oligomers, complexes composed of often symmetric...
Biomolecular Recognition Is Mediated by Weak Chemical Forces
The biomolecular recognition events that occur through structural complementarity are mediated by the weak chemical forces previously discussed. It is important to realize that, because these interactions are sufficiently weak, they are readily reversible. Consequently, biomolecular interactions tend to be transient rigid, static lattices of biomolecules that might paralyze cellular activities are not formed. Instead, a dynamic interplay occurs between metabolites and macromolecules, hormones...
Although Sucrose And Maltose Are Important To The Human Diet They Are Not Taken
FIGURE 7.18 The structures of several important disaccharides. Note that the notation HOH means that the configuration can be either a or If the OH group is above the ring, the configuration is termed The configuration is a if the OH group is below the ring as shown. Also note that sucrose has no free anomeric carbon atoms. the oxidation-reduction reactions characteristic of reducing sugars. Thus, sucrose is not a reducing sugar. Maltose, isomaltose, and cellobiose are all homodisaccharides...
H Lxr
c. Neither trypsin nor chymotrypsin treatment of the nonapep-tide released smaller fragments. However, combined trypsin and chymotrypsin treatment liberated free Arg. d. CNBr treatment of the eight-residue fragment left after combined trypsin and chymotrypsin action yielded a six-residue fragment containing Cys, Gly, Pro, Tyr, and Val and a dipeptide. e. Treatment of the six-residue fragment with -mercap-toethanol yielded two tripeptides. Brief Edman analysis of the tripeptide mixture yielded...
Info Moc
FIGURE 3.5 The dependence of AS on temperature for the denaturation of chy-motrypsinogen. Adapted from Brandts, J. F, 1964. The thermodynamics of protein denaturation. I. The denatura-tion of chymotrypsinogen. Journal of the American Chemical Society 86 4291- 4301. FIGURE 3.6 Unfolding of a soluble protein exposes significant numbers of nonpolar groups to water, forcing order on the solvent and resulting in a negative AS for the unfolding process. Yellow spheres represent nonpolar groups blue...
Tetraterpenes
FIGURE 8.17 Many monoterpenes are readily recognized by their characteristic flavors or odors limonene in lemons citronellal in roses, geraniums, and some perfumes pinene in turpentine and menthol from peppermint, used in cough drops and nasal inhalers . The diterpenes, which are C20 terpenes, include retinal the essential light-absorbing pigment in rhodopsin, the photoreceptor protein of the eye , phytol a constituent of chlorophyll , and the gibberellins potent plant hormones . The triterpene...
Viruses Are Supramolecular Assemblies Acting as Cell Parasites
Viruses are supramolecular complexes of nucleic acid, either DNA or RNA, encapsulated in a protein coat and, in some instances, surrounded by a membrane envelope Figure 1.24 . The bits of nucleic acid in viruses are, in reality, mobile elements of genetic information. The protein coat serves to protect the nucleic acid and allows it to gain entry to the cells that are its specific hosts. Viruses unique for all types of cells are known. Viruses infecting bacteria are called bacteriophages...
C Ritical Developments In Biochemistry 1
Thermodynamics of the Folding Process in Globular Proteins Section 6.1 considered the noncovalent binding energies that stabilize a protein structure. However, the folding of a protein depends ultimately on the difference in Gibbs free energy AG between the folded F and unfolded U states at some temperature T AG Gp - GU AH - TAS Hf - Hu - T Sf - SU In the unfolded state, the peptide chain and its R groups interact with solvent water, and any measurement of the free energy change upon folding...
H J
tant components of the vitreous humor in the eye and of synovial fluid, the lubricant fluid of joints in the body. The chondroitins and keratan sulfate are found in tendons, cartilage, and other connective tissue, whereas dermatan sulfate, as its name implies, is a component of the extracellular matrix of skin. Glycosaminoglycans are fundamental constituents of proteoglycans discussed later . 1. Draw Haworth structures for the two possible isomers of D-altrose Figure 7.2 and D-psicose Figure...
Info Onn
Molecular weight of amino acid minus that of water. Frequency of occurrence of each amino acid residue in the polypeptide chains of 207 unrelated proteins of known sequence. Values from Klapper, M. H., 1977. Biochemical and Biophysical Research Communications 78 1018-1024. The electron transport protein, cytochrome c, found in the mitochondria of all eukaryotic organisms, provides the best-studied example of homology. The polypeptide chain of cytochrome c from most species contains slightly...
Pep
FIGURE 3.13 Phosphoenolpyruvate PEP is produced by the enolase reaction in glycolysis see Chapter 19 and in turn drives the phosphorylation of ADP to form ATP in the pyruvate kinase reaction. value of aGdepends on the pKa values of the starting anhydride and the product phosphoric and carboxylic acids, and of course also on the pH of the medium. The largest value of aGin Table 3.3 belongs to phosphoenolpyruvate or PEP, an example of an enolic phosphate. This molecule is an important...
So2ch3
Farnesyl transferase R CMSCKCVLS COO- M Additional modification methylation and palmitoylation , A Ras CMSCKC COO- f Ras J CMSCKCVLS COO- v V_y
Www.isiamino.com
Classic bulge G-1 bulge Wide bulge FIGURE 6.13 Three different kinds of -bulge structures involving a pair of adjacent polypeptide chains. Adapted from Richardson, J. S, 1981. Advances in Protein Chemistry 34 167-339. One final secondary structure, the -bulge, is a small piece of nonrepetitive structure that can occur by itself, but most often occurs as an irregularity in antiparallel -structures. A -bulge occurs between two normal -structure hydrogen bonds and comprises two residues on one...
Biological Macromolecules and Their Building Blocks Have a Sense or
The macromolecules of cells are built of units amino acids in proteins, nucleotides in nucleic acids, and carbohydrates in polysaccharides that have structural polarity. That is, these molecules are not symmetrical, and so they can be thought of as having a head and a tail. Polymerization of these units to form macromolecules occurs by head-to-tail linear connections. Because of this, the polymer also has a head and a tail, and hence, the macromolecule has a sense or direction to its structure...
Info Gid
Adapted from Klotz, I. M., 1986. Introduction to BiomolecularEnergetics. New York Academic Press. Adapted from Klotz, I. M., 1986. Introduction to BiomolecularEnergetics. New York Academic Press. characterized in terms of appropriate measures of transfer potential pKa and reduction potential, respectively . As shown in Table 3.4, the notion of group transfer is fully analogous to those of ionization potential and reduction potential. The similarity is anything but coincidental, because all of...
O Fpf
FIGURE 7.8 D-Ribose and other five-carbon saccharides can form either furanose or pyra-nose structures. merely for illustrative purposes and involves no change in configuration of the saccharide molecule. The rules previously mentioned for assignment of a- and -configurations can be readily applied to Haworth projection formulas. For the D-sugars, the anomeric hydroxyl group is below the ring in the a-anomer and above the ring in the -anomer. For L-sugars, the opposite relationship holds. As...
Courtesy Of D. E. Nicholson University Of Leeds And Sigma Chemical Co. St.
FIGURE 6.21 Collagen fibers are stabilized and strengthened by Lys-Lys cross-links. Aldehyde moieties formed by lysyl oxidase react in a spontaneous nonenzymatic aldol reaction. HC CH2 2 CH2 C C CH2 2 CH lysine residues Figure 6.22 . These cross-links form between the N-terminal region of one tropocollagen and the C-terminal region of an adjacent tropocol-lagen in the fibril. Fibrous proteins, although interesting for their structural properties, represent only a small percentage of the...
Metabolic Map. Courtesy Of T. H. E. Nicholson University Of Leeds And Sigma
FIGURE 1.20 Reproduction of a metabolic map. Courtesy of D. E. Nicholson, University of Leeds and Sigma Chemical Co, St. Louis, MO. Figure 1.20 . All of these reactions, many of which are at apparent cross-purposes in the cell, must be fine-tuned and integrated so that metabolism and life proceed harmoniously. The need for metabolic regulation is obvious. This metabolic regulation is achieved through controls on enzyme activity so that the rates of cellular reactions are appropriate to cellular...
Biomolecules Are Carbon Compounds
All biomolecules contain carbon. The prevalence of C is due to its unparalleled versatility in forming stable covalent bonds by electron-pair sharing. Carbon can form as many as four such bonds by sharing each of the four electrons in its outer shell with electrons contributed by other atoms. Atoms commonly found in covalent linkage to C are C itself, H, O, and N. Hydrogen can form one such bond by contributing its single electron to formation of an electron pair. Oxygen, with two unpaired...
Example 1
What is the pH when 100 mL of 0.1 N NaOH is added to 150 mL of 0.2 M HAc if pKa for acetic acid 4.76 100 mL 0.1 N NaOH 0.01 mol OH, which neutralizes 0.01 mol of HAc, giving an equivalent amount of Ac 0.02 mol of the original 0.03 mol of HAc remains essentially undissociated. The final volume is 250 mL. pH pKa log10 4.76 log 0.01 mol 0.02 mol If 150 mL of 0.2 M HAc had merely been diluted with 100 mL of water, this would leave 250 mL of a 0.12 M HAc solution. The pH would be given by Clearly,...
Irs1
A number of proteins do not perform any obvious chemical transformation but nevertheless can regulate the ability of other proteins to carry out their physiological functions. Such proteins are referred to as regulatory proteins. A well-known example is insulin, the hormone regulating glucose metabolism in animals. Insulin is a relatively small protein 5.7 kD and consists of two polypeptide chains held together by disulfide cross-bridges. Other hormones that are also proteins include pituitary...
Ho P Och
FIGURE 1.9 a Amino acids build proteins by connecting the -carboxyl C atom of one amino acid to the -amino N atom of the next amino acid in line. b Polysaccharides are built by combining the C-1 of one sugar to the C-4 O of the next sugar in the polymer. c Nucleic acids are polymers of nucleotides linked by bonds between the 3'-OH of the ribose ring of one nucleotide to the 5'-PO4 of its neighboring nucleotide. All three of these polymerization processes involve bond formations accompanied by...
Info Bif
FIGURE 4.21 Chromatographic fractionation of a synthetic mixture of amino acids on ion exchange columns using Amberlite IR-120, a sulfonated polystyrene resin similar to Dowex-50. A second column with different buffer conditions is used to resolve the basic amino acids. Adapted from Moore, S., Spackman, D., and Stein, W., 1958. Chromatography of amino acids on sulfonated polystyrene resins. Analytical Chemistry 301185-1190. FIGURE 4.22 HPLC chromatogram of amino acids employing precolumn...
Problems
1. The nutritional requirements of Escherichia coli cells are far simpler than those of humans, yet the macromolecules found in bacteria are about as complex as those of animals. Since bacteria can make all their essential biomolecules while subsisting on a simpler diet, do you think bacteria may have more biosynthetic capacity and hence more metabolic complexity than animals Organize your thoughts on this question, pro and con, into a rational argument. 2. Without consulting chapter figures,...
H Eep
H helix former I indifferent B helix breaker C random coil secondary tendency. H helix former I indifferent B helix breaker C random coil secondary tendency. The tendencies of the amino acids to stabilize or destabilize a-helices are different in typical proteins than in polyamino acids. The occurrence of the common amino acids in helices is summarized in Table 6.1. Notably, proline and hydroxyproline act as helix breakers due to their unique structure, which fixes the value of the Ca N C bond...
Structural Complementarity Determines Biomolecular Interactions
Structural complementarity is the means of recognition in biomolecular interactions. The complicated and highly organized patterns of life depend upon the ability of biomolecules to recognize and interact with one another in very specific ways. Such interactions are fundamental to metabolism, growth, replication, and other vital processes. The interaction of one molecule with another, a protein with a metabolite, for example, can be most precise if the structure of one is complementary to the...
Advances In Protein Chemistry Wetlaufer 1962
200 220 240 260 280 300 320 Wavelength nm FIGURE 4.15 The ultraviolet absorption spectra of the aromatic amino acids at pH 6. From Wetlaufer, D.B., 1962. Ultraviolet spectra of proteins and amino acids. Advances in Protein Chemistry 17 303390. 200 220 240 260 280 300 320 Wavelength nm FIGURE 4.15 The ultraviolet absorption spectra of the aromatic amino acids at pH 6. From Wetlaufer, D.B., 1962. Ultraviolet spectra of proteins and amino acids. Advances in Protein Chemistry 17 303390. phorescence...
Info Hla
1. Without consulting chapter figures, draw Fischer projection formulas for glycine, aspartate, leucine, isoleucine, methionine, and threonine. 2. Without reference to the text, give the one-letter and three-letter abbreviations for asparagine, arginine, cysteine, lysine, proline, tyrosine, and tryptophan. 3. Write equations for the ionic dissociations of alanine, glutamate, histidine, lysine, and phenylalanine. 4. How is the pKa of the a-NH3 group affected by the presence on an amino acid of...
Info Eaa
Cation exchange bead before adding sample e Lysine, the most positively charged amino acid, is eluted last positively charged amino acid, is eluted first e Lysine, the most positively charged amino acid, is eluted last FIGURE 4.19 Operation of a cation exchange column, separating a mixture of Asp, Ser, and Lys. a The cation exchange resin in the beginning, Na form. b A mixture of Asp, Ser, and Lys is added to the column containing the resin. c A gradient of the elut-ing salt e.g., NaCl is added...
H Lcu
b. CNBr treatment yielded a pentapeptide and a tripeptide containing phenylalanine. c. Chymotrypsin treatment yielded a tetrapeptide containing a C-terminal indole amino acid, and two dipeptides. d. Trypsin treatment yielded a tetrapeptide, a dipeptide, and free Lys and Phe. e. Clostripain yielded a pentapeptide, a dipeptide, and free Phe. What is the amino acid sequence of this octapeptide 7. Amino acid analysis of an octapeptide gave the following results 1 Ala 1 Arg 1 Asp 1 Gly 3 Ile 1 Val 1...
Info Bbr
Creighton, T. E., 1997. How important is the molten globule for correct protein folding Trends in Biochemical Sciences 22 6-11. Dickerson, R. E., and Geis, I., 1969. The Structure and Action of Proteins. New York Harper and Row. Dill, K. A., and Chan, H. S., 1997. From Levinthal to pathways to funnels. Englander, S. W., and Mayne, L., 1992. Protein folding studied using hydrogen exchange labeling and two-dimensional NMR. Annual Review of Biophysics and Biomolecular Structure 21 243-265. Hardie,...
Chemistry Is the Logic of Biological Phenomena
Swamp Animals and Birds on the River Gambia, c. 1912 by Harry Hamilton Johnston 1858-1927 . Royal Geographical Society, London The Bridgeman Art Library. olecules are lifeless. Yet, in appropriate complexity and number, molecules compose living things. These living systems are distinct from the inanimate world because they have certain extraordinary properties. They can grow, move, perform the incredible chemistry of metabolism, respond to stimuli from the environment, and, most significantly,...