Chapter 19 Proteins PDF

Chapter 19 Proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part....

Chapter 19 Proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 1  Learning Objectives (1 of 2) Identify the characteristic parts of alpha-amino acids Draw structural formulas to illustrate the various ionic forms assumed by amino acids Write reactions to represent the formation of peptides and proteins Describe uses for important peptides Describe proteins in terms of the following characteristics: size, function, classification as fibrous or globular, and classification as simple or conjugated Explain what is meant by the primary structure of proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 2  Learning Objectives (2 of 2) Describe the role of hydrogen bonding in the secondary structure of proteins Describe the role of side-chain interactions in the tertiary structure of proteins Explain what is meant by the quaternary structure of proteins Describe the conditions that can cause proteins to hydrolyze or become denatured Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 3  Amino Acids Building blocks of proteins Only 20 amino acids are commonly found in natural proteins Alpha-amino acid: Contains both an amino group and a carboxylate group Amino group is attached to the carbon next to the carboxylate group Each amino acid has a name, a three-letter abbreviation, and a one-letter abbreviation Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 4  Amino Acids and R Group Amino acids are categorized into groups based on the polarity of the R groups Neutral and nonpolar side chains (e.g. —CH3) Neutral but polar side chains (e.g. —CH2—OH) Basic side chains (e.g. —CH2CH2CH2CH2—NH3+) or Acidic side chains (e.g. —CH2—COO—) Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 5 Table 19.1 - Common Amino Acids of Proteins (1 of 3) Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 6 Table 19.1 - Common Amino Acids of Proteins (2 of 3) Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 7 Table 19.1 - Common Amino Acids of Proteins (3 of 3) Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 8  Stereochemistry of Amino Acid In 19 of the 20 amino acids, the α-carbon is chiral Glycine is the achiral amino acid With few exceptions, the amino acids in living systems exist in the ʟ form Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 9  Amino Acid Properties White crystalline solids High melting points High water solubilities Exist in ionic form in solid state and in solution Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 10  Zwitterion (1 of 3) a. Dipolar ion that carries both a positive and a negative charge as a result of an internal acid–base reaction in an amino acid molecule Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 11  Zwitterion (2 of 3) Net charge of the zwitterion is zero, but the form in acid solution has a net positive charge Converted into a negatively charged form when it loses a proton Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 12  Zwitterion (3 of 3) Isoelectric point: Characteristic solution pH at which an amino acid has a net charge of zero R group Isoelectric point Neutral About pH 6 Acidic Less than pH 6 Basic More than pH 6 At pH values above the isoelectric point, the amino acid has a net negative value At pH values below the isoelectric point, the amino acid has a net positive value Amino acid solutions can act as buffers because they react with both H3O+ and OH− Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 13 Example 19.3 - Drawing Zwitterion Structures Draw the structure of the amino acid leucine In acidic solution at a pH below the isoelectric point In basic solution at a pH above the isoelectric point Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 14  Example 19.3 – Solution ( 1 of 2) In acidic solution, the carboxylate group of the zwitterion picks up a proton Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 15  Example 19.3 – Solution ( 2 of 2) In basic solution, the group of the zwitterion loses a proton Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 16  Reactions of Amino Acid: Oxidation Cysteine, the only sulfhydryl (—SH)-containing amino acid, can easily be oxidized to form a disulfide bond (—S—S—) Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 17 Reactions of Amino Acid: Peptide Formation (1 of 3) Peptide bond formation enables amino acids to make polymers by forming amide (peptide) linkages Dipeptides: Compounds formed when two amino acids are bonded by an amide linkage Peptide linkage or peptide bond: Amide linkage between amino acids that results when the amino group of one acid reacts with the carboxylate group of another Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 18 Reactions of Amino Acid: Peptide Formation (2 of 3) Order of linkage is important because two different dipeptides can be formed when two unique amino acids react Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 19  Reactions of Amino Acid: Peptide Formation (3 of 3) Peptide: Amino acid polymer of short chain length Polypeptide: Intermediate chain length polymer with less than 50 amino acids Protein: Polymer with more than 50 amino acids Amino acid residue: Amino acid that is a part of a peptide, polypeptide, or protein chain By convention, peptides are written with the N-terminal residue on the left and the C-terminal residue on the right Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20  Naming Peptides Peptides are named by starting at the N-terminal end of the chain and listing the amino acid residues in order from left to right Structural formulas are simplified by representing peptide and protein structures in terms of three-letter abbreviations for the amino acid residues with dashes to show peptide linkages Examples Glycylalanine - Gly-Ala Alanylglycylvaline can be arranged as Ala-Gly-Val, Ala-Val-Gly, Val-Ala-Gly, Val-Gly-Ala, Gly-Val-Ala, and Gly-Ala-Val Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 21  Important Peptides: Vasopressin and Oxytocin Hormones released by the pituitary gland Classified as nonapeptides Have disulfide bridges Disulfide bridge: Bond produced by the oxidation of —SH groups on two cysteine residues Bond loops or holds two peptide chains together Structures differ only in third and eighth amino acid residues Vasopressin is known as an antidiuretic hormone Decreases urine formation Oxytocin causes uterine contractions and stimulates lactation of mammary glands Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 22 Figure 19.3 - Structures of Vasopressin and Oxytocin Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 23  Important Peptides: Adrenocorticotropic Hormone (ACTH) Synthesized by the pituitary gland Contains 39 amino acids residues Has no disulfide bridges Regulates the production of steroids in the cortex of the adrenal gland Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 24  Table 19.2 - Examples of Peptide or Protein Hormones Name Origin Action Adrenocorticotropic hormone (ACTH) Pituitary Stimulates production of adrenal hormones Angiotensin II Blood plasma Causes blood vessels to constrict Follicle-stimulating hormone (FSH) Pituitary Stimulates sperm production and follicle maturation Gastrin Stomach Stimulates stomach to secrete acid Glucagon Pancreas Stimulates glycogen metabolism in liver Human growth hormone (HGH) Pituitary Stimulates growth and cell reproduction Insulin Pancreas Controls metabolism of carbohydrates Oxytocin Pituitary Stimulates contraction of uterus and other smooth muscles Prolactin Pituitary Stimulates lactation Somatostatin Hypothalamus Inhibits production of HGH Vasopressin Pituitary Decreases volume of urine excreted Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 25  Characteristics of Proteins - Size Large natural polymers of amino acids Have molecular weights that vary from about 6000 to several million u Too large to pass through cell membranes Contained inside the normal cells where they are formed Can leak out if cell is damaged by disease or trauma Persistent excessive amounts of protein in urine can indicate damaged kidneys Presence of enzymes in blood can indicate a heart attack Human cell contains 9000 different proteins, and the human body contains 100,000 different proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 26  Table 19.3 - Molecular Weights of Some Common Proteins Protein Molecular Weight (u) Number of Amino Acid Residues Insulin 6,000 51 Cytochrome c 16,000 104 Growth hormone 49,000 191 Hemoglobin 65,000 574 Hexokinase 96,000 730 Gamma globulin 176,000 1320 Myosin 800,000 6100 Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 27  Acid–Base Properties of Proteins Proteins take the form of zwitterions Have characteristic isoelectric points and can behave as buffers in solutions Can be in solution or form stable colloidal dispersions Depends on the repulsive forces acting between molecules with like charges on their surfaces Repulsive forces are at their weakest at the isoelectric point, when the net charge is zero Proteins tend to clump together and precipitate from solutions in which pH is equal to or close to the isoelectric point Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 28  Table 19.4 - Biological Functions of Proteins (1 of 2) Function Examples Occurrence or Role Catalysis lactate dehydrogenase Oxidizes lactic acid cytochrome c Transfers electrons DNA polymerase Replicates and repairs DNA Structure viral-coat proteins Sheath around nucleic acid of viruses glycoproteins Cell coats and walls α-keratin Skin, hair, feathers, nails, and hooves β-keratin Silk of cocoons and spiderwebs collagen Fibrous connective tissue elastin Elastic connective tissue Storage ovalbumin Egg-white protein casein A milk protein ferritin Stores iron in the spleen gliadin Stores amino acids in wheat zein Stores amino acids in corn Protection antibodies Form complexes with foreign proteins fibrinogen Involved in blood clotting thrombin Involved in blood clotting Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 29  Table 19.4 - Biological Functions of Proteins (2 of 2) Function Examples Occurrence or Role Regulation insulin Regulates glucose metabolism growth hormone Stimulates growth of bone Nerve impulse rhodopsin Involved in vision transmission acetylcholine Impulse transmission in nerve cells receptor protein Movement Myosin Thick filaments in muscle fiber actin Thin filaments in muscle fiber dynein Movement of cilia and flagella Transport hemoglobin Transports O2 in blood myoglobin Transports O2 in muscle cells serum Transports fatty acids in blood albumin Transports iron in blood transferrin Transports copper in blood ceruloplasmin Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 30  Classification of Proteins Based on Their Shape Fibrous proteins: Made up of long rod-shaped or stringlike molecules that intertwine to form fibers Water insoluble and components of connective tissue, elastic tissue, hair, and skin Examples - Collagen, elastin, and keratin Globular proteins: Form stable suspensions or dissolve in water Transport proteins Examples - Hemoglobin and transferrin Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 31  Classification of Proteins Based on Composition Simple proteins: Made up entirely of amino acid residues Conjugated proteins: Contain amino acid residues and other organic or inorganic components Prosthetic groups: Non–amino acid parts of conjugated proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 32  Table 19.5 - Conjugated Proteins Class Prosthetic Groups Examples Nucleoproteins nucleic acids (DNA, RNA) Viruses Lipoproteins lipids Fibrin in blood, serum lipoproteins Glycoproteins carbohydrates Gamma globulin in blood, mucin in saliva Phosphoproteins phosphate groups Casein in milk Hemoproteins heme Hemoglobin, myoglobin, cytochromes Metalloproteins iron Ferritin, hemoglobin zinc Alcohol dehydrogenase Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 33  Primary Protein Structure Linear sequence of amino acid residues in a protein chain Determines secondary and tertiary structures Important for the functioning of proteins Small variations in the primary structure can cause profound differences in the functioning of proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 34 Table 19.6 - Some Proteins Whose Sequence of Amino Acids Is Known Protein Number of Amino Acid Residues Insulin 51 Hemoglobin α-chain 141 β-chain 146 Myoglobin 153 Human growth hormone 191 Trypsinogen 229 Carboxypeptidase A 307 Gamma globulin 1320 Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 35  Secondary Protein Structure Arrangement of protein chains into patterns as a result of hydrogen bonds between amide groups of amino acid residues in the chain Includes α-helix β-pleated sheet Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 36  α-Helix Structure Occurs when a single protein chain twists to resemble a coiled helical spring Held in shape by intramolecular hydrogen bonds between carbonyl oxygens and amide hydrogens in adjacent turns of the helical backbone All amide groups in the helix are hydrogen bonded Two or more helices interact to form a cable in α-Keratin (found in hair), myosin (found in muscle), epidermin (found in skin), and fibrin (found in blood clots) Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 37 Figure 19.10 - Two Representations of the α-Helix Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 38  β-Pleated Sheet Occurs when several protein chains lie side by side and are held in position by hydrogen bonds between the carbonyl oxygen atoms of one chain and the amide hydrogen atoms of an adjacent chain Found extensively only in silk protein Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 39  Figure 19.12 - β-Pleated Sheet Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 40 Figure 19.13 - Segment of a Protein Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 41  Tertiary Protein Structure (1 of 2) Specific three-dimensional shape of a protein resulting from interactions between R groups of amino acid residues Types of R-group interactions Disulfide bridges - Form between cysteine residues Salt bridges - Result of ionic bonds that form between the ionized side chain of an acidic amino acid and the side chain of a basic amino acid Hydrogen bonds - Form between side chains that possess the following functional groups: Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 42  Tertiary Protein Structure (2 of 2) Hydrophobic interactions - Form between nonpolar residues In an aqueous environment, the interaction of hydrophilic and hydrophobic side chains with water determines shape Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 43 Figure 19.14 - R-Group Interactions Leading to Tertiary Protein Structure Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 44  Figure 19.15 - Globular Protein with a Hydrophobic Region and Polar Groups Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 45  Quaternary Protein Structure (1 of 2) Arrangement of subunits that form a larger protein Subunit: Polypeptide chain that has primary, secondary, and tertiary structures Conjugated proteins with quaternary structure contain subunits and prosthetic groups, which may be organic or inorganic components Heme is an example of a prosthetic group Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 46  Quaternary Protein Structure (2 of 2) Hemoglobin Subunits - Two identical alpha chains and two identical beta chains Held together by hydrophobic forces Contains four heme groups Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 47  Protein Hydrolysis Heating of a peptide or protein in the presence of an acid or base causes it to break into smaller peptides or amino acids based on: Hydrolysis time Temperature pH Process of protein digestion involves hydrolysis reactions that are catalyzed by enzymes in the digestive tract Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 48  Protein Denaturation Process by which a protein loses its characteristic native structure and function Native state: Natural three-dimensional conformation of a functional protein Occurs when protein is exposed to physical or chemical conditions Leads to loss of biological activity (function) May cause some proteins to precipitate Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 49 Figure 19.18 - Protein Denaturation and Coagulation of Proteins Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 50 Table 19.7 - Substances and Conditions That Denature Proteins Substance or Condition Effect on Proteins Examples Heat and ultraviolet light Disrupt hydrogen bonds and ionic Cooking food, sterilizing medical instruments attractions by making molecules vibrate too violently; produce coagulation, as in cooking an egg Organic solvents (ethanol Disrupt hydrogen bonds in proteins and Disinfectant used to prepare the skin for an and isopropyl alcohol) probably form new ones with the proteins injection Strong acids or bases Disrupt hydrogen bonds and ionic Cheese and yogurt preparation, as lactic attractions; prolonged exposure results in acid denatures milk protein hydrolysis of protein Agitation Disrupts hydrogen bonds and hydrophobic Whipped cream and meringue interactions Detergents and soaps Disrupt hydrogen bonds, hydrophobic Household soaps and detergents interactions, and ionic attractions Heavy metals Form bonds to thiol groups and precipitate Lead and mercury poisoning proteins as insoluble heavy-metal salts Seager, Slabaugh, Hansen, General, Organic, and Biochemistry, Tenth Edition. © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 51