Concept explainers
(a)
Interpretation:
The amino acid associated with the hydrophobic side chain needs to be identified.
Concept introduction:
Amino acids are organic compounds with both amino and
Here, R group is different for different amino acids.
(b)
Interpretation:
The amino acid associated with basic side chain needs to be identified.
Concept introduction:
Amino acids are organic compounds with both amino and carboxylic acid groups. The general formula of the amino acid is shown as follows:
Here, R group is different for different amino acids.
(c)
Interpretation:
Theamino acid associated with three ionizable group needs to be identified.
Concept introduction:
Amino acids are organic compounds with both amino and carboxylic acid groups. The general formula of the amino acid is shown as follows:
Here, R group is different for different amino acids.
(d)
Interpretation:
Theamino acid having pKa of about 10 in proteins needs to be identified.
Concept introduction:
Amino acids are the building blocks of proteins and protein plays a vital role in almost all biological processes. A huge proportion of our cells, tissue and muscles are made up of amino acids, means they carry out several significant bodily functions, like, providing cells their structure.
(e)
Interpretation:
The amino acid which is modified form of phenylalanine needs to be determined.
Concept introduction:
Amino acids are organic compounds with both amino and carboxylic acid groups. The general formula of the amino acid is shown as follows:
Here, R group is different for different amino acids.
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BIOCHEMISTRY W/1 TERM ACHEIVE ACCESS
- A cytosolic protein has an important alpha amino group. The pKa of this group is approximately 8 when exposed to water outside of a protein. 1. What would happen to the pKa if this group was instead buried in the hydrophobic interior of the protein? Explain. 2. Let’s say in the hydrophobic interior of the protein, the group forms an ionic bond with a carboxylate group of the side chain of a charged Asparagine residue. How would the pKa of this alpha amino group compare with the pKa of the alpha amino group in the hydrophobic interior of the protein without a nearby Asparagine residue to form this ionic bond? Explain.arrow_forwardWhich intermolecular forces are important in acetic acid, CH3 –(C=0)-oh? A particular amino acid contains a- CHNH3+ group. Is this amino acid more likely to be found on the inside or the outside of the folded protein? Briefly explain. The addition of ethanol, CH3CHOH, t an aqueous solution lowers the surface tension of the solution. Predict whether adding ethanol to an aqueous protein solution will tend to stabilize or unfold the protein. Briefly explain.arrow_forwardDenaturation of Proteins The following are four levels of protein structures. Identify the inter- and intramolecular forces of attractions that stabilized each level. Level of Protein Structure Forces of Attraction Present Primary Secondary Tertiary Quaternary 2.) What is denaturation? 3.) What are denaturing agents? Give three examples and describe their effects on protein. 4.) Differentiate reversible and irreversible denaturation. 5.)Why is 70% ethanol is more effective than 100% ethanol to kill bacteria?arrow_forward
- Proteins and Amino Acids A. Acid-base properties of proteins: 1. Data a. Color phenolphthalein-NaOH solution -before adding casein : colorless - after adding casein :colorless cloudy b. Color of methyl orange-HCl solution - before adding casein :Blue - after adding casein : Pink 2. Why did the solutions change color? 3. Which property of proteins is illustrated by the above? 4. Why as methyl orange used in place of phenolphthalein in the second part of this procedure? B. Isoelectric point of casein: 1. Data Initial pH of milk Final pH of milk 2. What is the isoelectric point of casein? C. Denaturation of proteins: A. pH 1. Observations: a. Tube no. 1: concentrated HCI b. Tube No. 2: concentrated HNO, c. Tube No. 2: concentrated H,SO, 2. Which structure(s) of the protein were disrupted in this procedure?arrow_forwardThe structure of ephedrine isgiven, The pKa for ephedrine is 9.6. Answer the following questions about aqueous solutions of ephedrine. a. Draw the structure of the principal chemical form of ephedrine that results when it isdissolved in water.b. Draw the structure of the principal chemical form of ephedrine that results when it is dissolved in a buffer at a physiologically relevant pH of 7.4.c. Calculate the pH that results when 0.3 mole of ephedrine is dissolve in 2.0 L of 0.05 M perchloric acid (HClO4).arrow_forwardDetermine the net charge (to the nearest integer) on the following peptide at pH 5 AND pH 12. Estimate the isoelectric point (pl) for this peptide: H2N-Leu-Gly-Lys-Glu-COOH Assume the pK,s for functional groups are: alpha-amino 6. alpha-carboxy sidechain-amino (Lys) 10.5 sidechain-carboxy (Glu) 4.2 O Net charge at pH 5 and 12 is 0 and -2, respectively, pl =6.6 O Net charge at pH 5 and 12 is 0 and -2, respectively, pl =3.1 O Net charge at plH 5 and 12 is +2 and -1, respectively, pl =7.5 O Nct charge at pH 5 and 12 is +1 and -1. respectively,. pl -4.5 2.arrow_forward
- A protein gives, under conditions of buffer composition, pH, and temperaturethat are close to physiological conditions, a molecular weight by size exclusion measurements of 140,000 g/mol. When the same protein is studiedby SDS gel electrophoresis in the absence or presence of the reducing agent β-mercaptoethanol (BME), the patterns seen, respectively, in lanes A and B are observed. Lane C contains standards of molecular weight indicated. From these data, describe the native protein, in terms of the kinds of subunits present, the stoichiometry of subunits, and the kinds of bonding(covalent, noncovalent) existing between subunits.arrow_forward1. Draw an approximate titration curve of the following amino acid. Label the approximate isoelectric point of arginine on the curve and be sure to label the axis of the graph appropriately. You DO NOT need to draw the structure of this amino acid here. Pk1= 1.92, pk2=8.99 and pk3=12.48. Show your work for determining the isoelectric point. You can draw out your curve within the text box or upload a drawing. A▾ B I - I B 7arrow_forwardThe polymer chains of glycosaminoglycans are widelyspread apart and bind large amounts of water.a. What two functional groups of the polymer make thisbinding of water possible?b. What type of bonding is involved?arrow_forward
- Protein A is made up of a single polypeptide chain; The molecular mass of A is 20,000 Da; the A molecule has 2 tryptophan residues, 5 tyrosine residues, and no disulfide bonds. Calculate what absorbance (at 280 nm) a solution of protein A will have at a concentration of 1.0 mg / mL, in a 1 cm cell. Write the calculations you have done.arrow_forwardWhich of the following statements are TRUE? Multiple answers:Multiple answers are accepted for this question PLEASE SHOW WORK FOR EACH PART AND EXPLAIN WHY EACH ANSWER CHOICE IS WRONG OR RIGHT a. The tripeptide His-Lys-Glu has a net charge of -2 at pH 8.0. b. The tripeptide Asp-Asp-Asp has a net charge of -3 at pH 7.0. c. The tetrapeptide His-His-His-His has a net charge of -1 at pH 7.0. d. There are 6 possible sequences for a tripeptide containing Arg - His - and Pro. e. Certain bacteria synthesize cyclic tetrapeptides. The net charge at pH 7.0 of a cyclic tetrapeptide consisting of two Pro and two Tyr is 0.arrow_forwardA mixture of Aspartic Acid (pl 2.98), Histidine (pl 7.59), Lysine (pl 9.74), Phenylalanine (pl 5.48) and Threonine (pl 6.53) are separated by cation exchange chromatography. What is the order of elution of these amino acids if you use gradient buffer system from pH 10 to pH 2. v First 1. Aspartic Acid v Second 2. Histidine v Third 3. Lysine 4. Phenylalanine v Fourth 5. Threonine v Fifth 6. No separationarrow_forward
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