Exam 24: Amino Acids and Proteins

The pH at which the concentration of the zwitterionic form (dipolar form)of an amino acid is at its highest and the concentrations of the cationic and anionic forms are equal is called the ___.

Which of these amino acids cannot be described as an l-amino acid?

The ¹H NMR spectrum for valine in D₂O is below. Assign the three major signals that appear in the spectrum. Why is the proton of the carboxylic acid absent?

Which of the following would provide a synthesis of valine?

Which of these amino acids contains a hydrophobic side chain?

Draw the structures of ValAla and AlaVal as zwitterions.

Which of these natural amino acids contains an imidazole ring?

C-Terminal amino acids can be identified through the use of ___.

A pentapeptide has the molecular formula: Asp,Glu,His,Phe,Val.Partial hydrolysis of the pentapeptide gives: Val·Asp,Glu·His,Phe·Val,and Asp·Glu.What is the amino acid sequence of the pentapeptide?

Calculate the pI of an amino acid with the following pK_as: pK_a1 = 2.2; pK_a2 = 9.3; pK_a3 = 4.3.

What is the configuration on all steric centers in these amino acids:

Which of the following would provide a synthesis of alanine?

What is the final product formed via the following reaction sequence? Give structural details of all significant intermediates.

The study of all proteins that are expressed in a cell at a given time is called ___.

Draw the product of the reaction of GlyCys with H₂O₂.

Draw the structure of R-aspartic acid.

The Edman degradation uses this reagent to identify the N-terminal amino acid of a peptide or protein.

What methods can be used for the identification of amino acids?

What is the pK_a of the carboxylic acids present in the following compounds in the given order:

What statements are true about enzymes? (I)They are biological catalysts,non-specific,that increase the reaction rate by 1000 times. (II)They are catalysts that increase reaction rates by a factor or 1 million or more. (III)Enzymes are remarkably specific,leading Fischer to formulate a lock-and-key hypothesis. (IV)Enzymes undergo an induced fit upon binding the substrate. (V)Enzyme and substrate form a complex