Amino Acids

Which of the following is a key property of amino acids that allows them to carry out a variety of biological functions?

What is the common structural feature shared by most alpha-amino acids?

Which type of amino acids are present in proteins?

What is the average molecular weight of all 20 amino acids?

Why is the average molecular weight of amino acid residues in proteins closer to 128?

Which of the following represents the relative configuration of amino acids?

What is the fourth substituent in glycine?

What is the average molecular weight of an amino acid residue if we subtract 18 for water released upon formation of peptide bond?

What is the molecular weight of alanine?

What is the molecular weight of proline?

Which of the following is true about peptides and proteins?

What is the equilibrium state for the hydrolysis of a peptide bond?

In the absence of a catalyst, how long would a peptide bond last in an aqueous environment?

Which terminus is used for numbering and naming peptides?

Which groups contribute to the isoelectric point (pI) of a peptide?

What are the functional non-amino acid components found in some proteins?

What is commonly used for preparative separation of proteins?

What is the charge of an amino acid with a pI of 9.7 in a pH of 7.0?

What does electrophoresis separate proteins based on?

What does the protein structure describe?

Which of the following is true about the classification of amino acids based on R groups?

Which of the following statements is true about cysteine?

Which of the following amino acids can absorb UV light at 270–280 nm?

Which of the following is true about the classification of amino acids based on R groups?

Which of the following is true about the structure of prothrombin?

Which of the following is true about the structure of collagen?

Which of the following is true about the structure of myosin?

Which of the following is true about the structure of elastin?

Which of the following is true about the general calculation of the isoelectric point (pI) for amino acids?

Which of the following is true about the ionization of amino acids?

Proteins are linear heteropolymers of ______

All amino acids (except proline) have: – an acidic ______ group – a basic ______ group – an a-hydrogen connected to the a-carbon - a fourth substituent (R), unique

Proteins only contain ______ amino acids

The average MW of an amino acid residue = ______

The average MW of all 20 AAs is about ______

If we subtract 18 for water released upon formation of peptide bond, the average MW of an amino acid residue = ______

The configuration of the four substituents around the chiral carbon is represented by ______

The average MW of protein AAs is closer to ______

The average MW of an amino acid residue is calculated by subtracting ______ for water released upon formation of peptide bond

The two stereoisomers (enantiomers) of alanine are represented by ______

the approximate number of amino acids in a protein can be obtained by dividing the MW of the protein by ______

Amino acids with uncharged side chains, such as glycine, have two pKa values: -the pKa of the a-carboxyl group is ______

The net charge of an amino acid is zero at a specific pH called the ______

The isoelectric point (pI) of an amino acid is calculated as the average of the pKa values that define the acid and base strengths of the ______

Ionizable side chains in amino acids can be titrated and their pKa values can be discerned if the values are more than ______ pH units apart

The pI of a zwitterion with an ionizable side chain can be calculated by identifying the pKa value that defines the acid strength and the pKa value that defines the base strength of the ______

The pI of a zwitterion with an ionizable side chain is obtained by taking the average of the two pKa values that define the acid and base strengths of the ______

The net charge of an amino acid is zero at the ______

Amino acids can act as ______ in solution

The pI of an amino acid is calculated as the average of the pKa values that define the acid and base strengths of the ______

Peptides are small condensation products of amino acids. They are 'small' compared to proteins, which have Mw > 10 kDa. Equilibrium lies on the side of hydrolysis thus energy is need to synthesize peptides BUT hydrolysis rate is slow (kinetically stable). In the absence of a catalyst a peptide bond in an aqueous environment would last > 1,000 years.

Numbering (and naming) starts from the ______: AA1 AA2 AA3 AA4 AA5 H2N-Ser-Gly-Tyr-Ala-Leu-COOH

In a typical peptide the terminal amino, carboxyl group contribute to the pI, as well as, the ______: - Peptides and proteins have characteristic pI values

Some proteins contain other chemical compounds besides amino acids: ______ - functional non-amino acid component - e.g. metal ions or organic molecules (coenzymes) coenzymes - organic ______ - e.g. NAD+ in lactate dehydrogenase prosthetic groups - covalently attached ______ - e.g. heme in myoglobin other modifications

Separation of proteins from crude extracts relies on ______: – Charge – Size – Affinity for a ligand – Solubility – Hydrophobicity – Thermal stability

Separation in analytical scale is commonly done by ______ – Electric field pulls amino acids or proteins according to their charge – Gel matrix hinders mobility of proteins according to their size and shape

An amino acid placed in an environment with a ______ below its pI will have a net (+) charge and move toward the negative electrode (cathode), ie pI = 9.7 in a ______ of 7.0. (At a ______ of 9.7, this amino acid will not migrate toward either electrode, while at ______ of 13 it will have a net (-) charge) A Rule to Remember .: if working ______ > pI, then protein or amino acid charge is negatively charged if working ______ < pI, then protein or amino acid charge is positively charged

A description of all covalent bonds, including disulfide bonds. Basically the amino acid sequence. Particular stable arrangements of amino acid residues resulting in recurring patterns Describes all of the ______ The arrangement in space of a protein which contains 2 or more polypeptide units

Structure, properties and naming of amino acids Structure and properties of peptides and proteins Ionization behavior of amino acids and peptides, and the isoelectric point Classes of conjugated proteins, cofactors, coenzymes, prosthetic groups ______, electrophoresis of proteins, behavior in electric field

The arrangement in space of a protein which contains 2 or more polypeptide units

Proteins are linear heteropolymers of _______

The average MW of an amino acid residue = _______

The pI of a zwitterion with an ionizable side chain can be calculated by identifying the pKa value that defines the acid strength and the pKa value that defines the base strength of the _______

The two stereoisomers (enantiomers) of alanine are represented by _______

The average MW of all 20 AAs is about _______

Proteins only contain _______ amino acids

Amino acids have properties that are well-suited to carry out a variety of biological functions – – – – Capacity to polymerize Useful acid-base properties Diverse physical properties Diverse chemical functionality 2 Most a-amino acids share common structural features and are _______

Ionizable side chains in amino acids can be titrated and their pKa values can be discerned if the values are more than _______ pH units apart

The average MW of protein AAs is closer to _______

In the absence of a catalyst a peptide bond in an aqueous environment would last _______

An amino acid placed in an environment with a pH below its pI will have a net (+) charge and move toward the negative electrode (cathode), i.e. pI = 9.7 in a pH of 7.0. (At a pH of 9.7, this amino acid will not migrate toward either electrode, while at a pH of 13 it will have a net (-) charge) A Rule to Remember .: if working ______ > pI, then protein or amino acid charge is negatively charged if working ______ < pI, then protein or amino acid charge is positively charged

Which of the following is a key property of amino acids that allows them to carry out a variety of biological functions?

What is the charge of an amino acid with a pI of 9.7 in a pH of 7.0?

All amino acids (except proline) have: – an acidic ______ group – a basic ______ group – an a-hydrogen connected to the a-carbon - a fourth substituent (R), unique

What does electrophoresis separate proteins based on?

Which of the following represents the relative configuration of amino acids?

Which of the following is true about the general calculation of the isoelectric point (pI) for amino acids?

Proteins are linear heteropolymers of ______

What is commonly used for preparative separation of proteins?

What are the functional non-amino acid components found in some proteins?

Peptides are 'small' compared to proteins, which have Mw > ______. Equilibrium lies on the side of hydrolysis thus energy is need to synthesize peptides BUT hydrolysis rate is slow (kinetically stable). In the absence of a catalyst a peptide bond in an aqueous environment would last > 1,000 years.

Numbering (and naming) starts from the ______: AA1 AA2 AA3 AA4 AA5 H2N-Ser-Gly-Tyr-Ala-Leu-COOH

Some proteins contain other chemical compounds besides amino acids: ______ - functional non-amino acid component - e.g. metal ions or organic molecules (coenzymes) coenzymes - organic ______ - e.g. NAD+ in lactate dehydrogenase prosthetic groups - covalently attached ______ - e.g. heme in myoglobin other modifications TABLE 3-4 Conjugated Proteins Class Prosthetic group Example Lipoproteins Lipids β1-Lipoprotein of blood Glycoproteins Carbohydrates Immunoglobulin G Phosphoproteins Phosphate groups Casein of milk Hemoproteins Heme (iron porphyrin) Hemoglobin Flavoproteins Flavin nucleotides Succinate dehydrogenase Iron Zinc Calcium Molybdenum Copper Ferritin Alcohol dehydrogenase Calmodulin Dinitrogenase Plastocyanin Metalloproteins

Separation of proteins from crude extracts relies on ______ in physical and chemical properties: – Charge – Size – Affinity for a ligand – Solubility – Hydrophobicity – Thermal stability Chromatography is commonly used for preparative separation

Separation in analytical scale is commonly done by ______ – Electric field pulls amino acids or proteins according to their charge – Gel matrix hinders mobility of proteins according to their size and shape

A description of all covalent bonds, including disulfide bonds. Basically the amino acid sequence. Particular stable arrangements of amino acid residues resulting in recurring patterns Describes all of the ______ The arrangement in space of a protein which contains 2 or more polypeptide units

Samples loaded onto the ______ matrix (polyacrylamide), together with MW markers, controls (purified proteins)

The arrangement in space of a protein which contains 2 or more polypeptide units

Amino acids can act as ______ in solution

The pI of a zwitterion with an ionizable side chain can be calculated by identifying the pKa value that defines the acid strength and the pKa value that defines the base strength of the ______