Acids, Bases and Buffers
Strong acids have a [blank] pKa, while weak acids have a [blank] pKa
Strong acids have a LOW pKa, while weak acids have a HIGH pKa
What four components bind to the alpha carbon of an AA?
Amino group (NH2)
Hydrogen
Carbonyl group (COOH)
R group (used for classification)
functional representative
What are the six major classes of enzymes?
Oxidoreductase
Catalyze oxidation-reduction reaction
Transferase
Catalyze transfer of C, N or P containing groups
Hydrolase (break with water)
Catalyze cleavage of bonds by addition of water
Lyase (think detergent)
Catalyzed cleavage of C-C, C-S and certain C-N bonds
Isomerase (Same molecular formula, different configuration)
Catalyze racemization of optical or geometric isomers
Ligase (connects)
Catalyze formation of bonds between carbon and O,S, N couples to hydrolysis of high-energy phosphate
Hb acts as a(n) [allosteric/simple] enzyme when describing kinetics, while Myoglobin acts as a(n) [allosteric/simple] enzyme
Allosteric , simple
Any acid (or base) that ionizes less than 10% in water at 0.5M
What is a weak acid (or base)?
The following mnemonic is used to help memorize the 10 essential amino acids. What does each letter mean?
I Love Lucy Very Much, Please Try To Help Arginine
Isoleucine, Leucine, Lysine, Valine, Methionine, Phenylalanine, Tryptophan, Threonine, Histidine and Arginine
TWO QUESTIONS:
1. Chromatography separates homogenate mixtures based on [name three physical properties]?
2. Electrophoresis uses an electric field that goes from the [blank] to [blank]?
1. Size, charge and affinity
(think: size exclusion chromatography and exchange chromatography)
2. cathode to anode
What are the properties of an enzyme?
Active sites
Catalytic efficiency
Specificity
Regulation
Localization
Think about the structure of heme.
What two chemical compounds does Iron form with?
Histidine and oxygen
A solution that resist change pH
What is a buffer?
Explain the reaction (hint: oxidation reaction)
Two Cysteine amino acids lose their H in the -SH (thiol group) to an O molecule
The two aa become covalently bonded at the S and H2O is produced
What is a Disulfide Bond reaction?
During protein purification via differential centrifugation, the FASTER the speed of the centrifuge the [smaller/larger] the cellular component in the pellet?
smaller
What factors affect enzyme reaction velocity?
substrate concentration, temperature and pH
True or False
Carbonic anhydrase is an enzyme found in RBC that responsible for removing carbon dioxide from the lungs
False.
Carbonic anhydrase is an enzyme found in RBC that responsible for removing carbon dioxide from the TISSUES.
CO2 is removed from the lungs via expiration
In the following reaction identify the conjugate acid and conjugate base
HA + H2O --> A- + H+
A- = conjugate base
H+ = conjugate acid
What are the 5 characteristics of a peptide bond?
1. partial double bond
2. rigid and planar
3. prevents free rotation around bond
4. bonds at alpha carbon can rotate depending on side chain
5. very stable bond, uncharged, will not release proton at pH 2-12
True or False
Denaturation reactions are strong enough to break the peptide bonds in the primary structure of proteins
False
Michaelis Menten Reaction Model Assumptions
Substrate concentration is greater then enzyme concentration
Substrate-enzyme concentration doesn't change with time
Rate of the reaction is measured when enzyme and substrate are mixed
Concentration of product is very small, so the back reaction of product to substrate is ignored
What active enzyme has cleavage points at Leucine, Phenylalanine, Tryptophan, Tyrosine and at which terminus (C or N)?
Pepsin
N terminus
What is the buffering range for a molecule with a pKa of 4.5
a pH between 3.5 and 5.5
Name 4 motifs
Beta-alpha-beta
Greek key
Beta-meander
Beta-barrel
8M urea and beta-mercaptoethanol
True of False the following statement applies to the presence of a noncompetitive inhibitor?
The affinity is lowered (increased Km), but the same maximum velocity (Vmax) is reached
False.
This is applicable to competitive inhibition.
What do peptide bond cleavages result in?
destructive change, activation of a function and signaling in signaling pathway