Histidine is one of the 20 amino acids found in proteins. Shown here is a fully protonated histidine molecule, where the numbers denote the p K a , values of the acidic groups: (a) Show stepwise ionization of histidine in solution. (Hint: The H - ion will first come off from the strongest acid group followed by the next strongest acid group and so on.) (b) A dipolar ion is one in which the species has an equal number of positive and negative charges. Identify the dipolar ion in part (a), (c) The pH at which the dipolar ion predominates is called the isoelectric point, denoted by p I . The isoelectric point is the average of the p K a values leading to and following the formation of the dipolar ion. Calculate the p I of histidine. (d) The histidine group plays an important role in buffering blood (the pH of blood is about 7.4). Which conjugate acid base pair shown in part (a) is responsible for maintaining the pH of blood?
Histidine is one of the 20 amino acids found in proteins. Shown here is a fully protonated histidine molecule, where the numbers denote the p K a , values of the acidic groups: (a) Show stepwise ionization of histidine in solution. (Hint: The H - ion will first come off from the strongest acid group followed by the next strongest acid group and so on.) (b) A dipolar ion is one in which the species has an equal number of positive and negative charges. Identify the dipolar ion in part (a), (c) The pH at which the dipolar ion predominates is called the isoelectric point, denoted by p I . The isoelectric point is the average of the p K a values leading to and following the formation of the dipolar ion. Calculate the p I of histidine. (d) The histidine group plays an important role in buffering blood (the pH of blood is about 7.4). Which conjugate acid base pair shown in part (a) is responsible for maintaining the pH of blood?
Solution Summary: The author explains the stepwise ionization of histidine in solution, and the conjugate acid–base pair involved in buffering of blood.
Histidine is one of the 20 amino acids found in proteins. Shown here is a fully protonated histidine molecule, where the numbers denote the
p
K
a
, values of the acidic groups:
(a) Show stepwise ionization of histidine in solution. (Hint: The
H
-
ion will first come off from the strongest acid group followed by the next strongest acid group and so on.) (b) A dipolar ion is one in which the species has an equal number of positive and negative charges. Identify the dipolar ion in part (a), (c) The pH at which the dipolar ion predominates is called the isoelectric point, denoted by pI. The isoelectric point is the average of the
p
K
a
values leading to and following the formation of the dipolar ion. Calculate the pI of histidine. (d) The histidine group plays an important role in buffering blood (the pH of blood is about 7.4). Which conjugate acid base pair shown in part (a) is responsible for maintaining the pH of blood?
Why does the anhydride react with the OH on the benzene rather than the OH on the carboxy group?
Answer the followings:
1- What is the IP for a amino acid? Give example.
2- What are the types of amino acids?
3- What are the structures of protein?
4- The N-Terminal analysis by the Edman method shows saralasin contains sarcosine at the N-
terminus. Partial hydrolysis of saralasin with dilute hydrochloric acid yields the following
fragments:
Tyr-Val-His
Sar-Arg-Val
His-Pro-Ala
Val-Tyr-Val
Arg-Val-Tyr
What is the structure of saralasin?
5. MATCH a term from the list below to each definition. Place the letter of the term in the blank
to the left of the definition.
a. Ligases
b. Fibrous proteins
c. Conjugated protein
d. Hydrolases
a.
b.
C.
e. Simple protein
f.
Globular proteins
g. Lyases
h.
Transferases
Proteins that are tough and insoluble in water.
Enzymes that catalyze the breaking away of a small molecule such as from a
substrate.
Enzymes that catalyze the bonding together of two substrates.
Answer the followings (Four):
1-What is the difference(s) between FOUR:
a. Glyceride and phosphoglyceride.
b. Wax and fat.
c. Soap and fatty acid.
d. HDL and LDL cholesterol
e. Phospho lipids and sphingosine.
2-What are the types of lipids?
3-What are the main lipid components of membrane structures?
4-How could lipids play important rules as signaling molecules and building units?
5. The Structure variety of Lipids makes them to play significant rules in our body.
Conclude briefly on this statement.
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