CHM132 Test4 Ch.16 Amino Acids, Proteins, & Enzymes

a-keratins are the fibrous proteins that make up hair, skin, & nails which are formed by _________ that are held together by ___________

3 alpha-helices coiled together, disulfide bonds(-S-S-) of the thiol (-SH) groups in cysteine a.a.

How many essential amino acids are there?

9

What is the most abundant protein in the body?

Collagen. found in connective tissue, blood vessels, skin, tendons, the cornea of the eye, and cartilage.

Proteins are big molecules that are 10,000 g/mol or larger. We typically measure the mass of proteins via

Dalton (Da) 10 K Dal or 10,000 Dal

What type of interaction could occur between the side chains of two cysteine residues?

Disulfide covalent bonds between thiol (-SH) groups

A globular protein that catalyzes a biological reaction is a(n)

Enzyme

What type of interaction could occur between the side chains of a serine and a threonine residue?

Hydrogen Bond

What type of interaction could occur between the side chains of a leucine and a valine residue?

Hydrophobic

What type of interaction could occur between the side chains of a lysine and an aspartic acid residue?

Ionic Salt Bridges

this class of enzyme forms covalent bonds between molecules using ATP energy.

Ligases

the addition or removal of double bonds without hydrolysis, the addition of CO2, the removal of NH3, and the reversible splitting of fructose are all examples of this enzyme class.

Lyases

Different classes of enzymes "LIL HOT"

Lyases, Isomerases, Ligases, Hydrolases, Oxidoreductases, Transferases

Identify the type of bonding found in the primary structure of a protein.

Peptide bonds

Collagen is an example of what structure?

Protein's secondary triple helix structure

The local folding of an alpha helix or beta-pleated sheet held together by hydrogen bonds is the

Secondary Structure

The molecule that reacts in an enzyme-catalyzed reaction is the

Substrate

isoelectric point (pI)

The pH at which an amino acid is predominantly in zwitterionic form & has an overall net charge of 0.

What enzyme catalyzes this reaction (ATP + protein ↔ ADP + phosphoprotein)

Transferase

Proteins are big enantiomers (T/F)

True

examples of contractile proteins

actin, myosin, titin, collagen, elastin

A pocket where the substrate is bound in the tertiary structure of a protein that catalyzes a biological reaction is the

active site

What are the most common types of secondary protein structure?

alpha helix, beta pleated sheet, & the triple helix.

examples of catalytic/enzyme proteins

amylase, ligase, sucrase, trypsin

Salt bridges are an ex of an interaction in tertiary protein structures that forms ionic bonds between ionized ______________ R groups of different amino acids.

basic or acidic

The tertiary structure is when a polypeptide folds into a compact, 3D shape stabilized by interactions between R groups of amino acids to form a _____________

biologically active protein.

Globular proteins do what for cells?

carry out the work with synthesis, transport, & metabolism.

examples of storage proteins

casein, ferritin

The amino acid methionine (Met, M) is the only a.a. specified by just 1 what?

codon, the start codon AUG

Disulfide bonds are seen in tertiary protein structures such as insulin. These disulfide bonds can link different polypeptide chains together by _____________ bonds that form between the __________ groups of cysteines

covalent, -SH (thiol)

Heavy Metal Ions Ag+ (silver), Pb2+(lead), Hg2+(mercury) are protein denaturing agents that disrupt these bonds.

disulfide bond in proteins by forming ionic bonds.

Myoglobin, Enzymes, & Hemoglobin are examples of what type of protein?

globular proteins.

What is the only amino acid out of the 20 that is not chiral?

glycine

What are some protein denaturing agents?

heat above 50 degrees celsius, acids (H3O) & bases (OH), organic compounds (ethanol or isopropyl alcohol), Heavy Metal Ions (Ag+, Pb2+, Hg2+), Agitation

What are the essential amino acids?

histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

Agitation (whipping) is a protein denaturing agent that disrupts these bonds

hydrogen bonds and hydrophobic interactions by stretching polypeptide chains.

Acids(H3O) & Bases (-OH) are protein denaturing agents that disrupt these bonds

hydrogen bonds between polar R groups, & ionic salt bridges btwn basic/acidic a.a.

Heat above 50 degrees Celsius is a protein denaturing agent that disrupts these bonds

hydrogen bonds, hydrophobic interactions between nonpolar R groups.

This class of enzyme promotes hydrolysis reactions (ex: splitting of peptide bonds in proteins)

hydrolase

Organic compounds such as ethanol or isopropyl alcohol are protein denaturing agents that disrupt these bonds

hydrophobic interactions

Tertiary protein structure involves these interactions between A.A. R groups in the polypeptide chain?

hydrophobic interactions, hydrophilic interactions, salt bridges, hydrogen bonds, disulfide bonds.

example of protective protein

immunoglobulin

examples of hormone proteins

insulin and growth hormone (GTH)/ somatotropin

Epimerases (D to L) such as L-alanine to D-alanine and the conversion of cis to trans are this class of enzyme

isomerases

Fibrous proteins consist of what and provide what?

long, thin, fiber like shapes, structure of cells and tissues, ex: a- & B-keratins

examples of transport proteins

myoglobin, hemoglobin, lipoprotein

this class of enzyme promotes either oxidation or reduction reactions (ex: catalyzing the metabolism of ethanol to acetic acid, or removal of 2H atoms to form a double bond)

oxidoreductases

The sequence of amino acids held together by peptide bonds in a polypeptide is the

primary structure

The quaternary structure is when two or more ______________ combine to form a biologically active protein

protein subunits

The interaction of four polypeptide chains in a protein is the

quaternary structure

What are some different classifications of proteins?

structural, contractile, transport, storage, hormone, enzyme, protection.

The compact folding of a polypeptide chain stabilized by interactions between R groups is the

tertiary structure of a protein

examples of structural proteins?

titin, keratin, collagen, elastin

This class of enzyme transfers a group between 2 compounds (ex: transfer of amino or phosphate groups)

transferase