Amino acids are metabolized by a transamination reaction in which the amino group of the amino acid changes places with the keto group of an a-keto acid; the amino acid and a new a-keto acid. Draw the products of the transamination reaction between threonine and 2-oxopentanedioate. • You do not have to consider stereochemistry. • Use the charge tools to adjust the charges of the amine and carboxyl groups to the form in which they would be found at physiological pH. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. • Separate multiple products using the + sign from the drop-down menu. ? √n [ Ⓡ ChemDoodle

Treatment of pentanedioic (glutaric) anhydride with ammonia at elevated temperature leads to a compound of molecular formula C5H7NO2. What is the structure of this product? [Hint: You need to think about the reactivity not only of acid anhydrides but also of amides and carboxylic acids]

(b) Describe how the charge of some amino groups in a protein might differ at pH 9.0 and pH 5.0. the charge on the amino group will differ at pH 5 and pH 9 which will depend on the pKa of the amino acid. (c) Describe how the charge of some carboxyl groups in a protein might differ at pH 9.0 and pH 5.0. charge on carboxyl group will differ at pH 5 and pH 9 which will depend on the pKa of the amino acid. (d) Given your answers to parts (b) and (c), what kind of intramolecular interactions in beta-galactosidase are most likely to be affected by a change in pH from 9.0 to 5.0? (e) Could the interactions you mention in part (d) affect the catalytic activity of beta-galactosidase?

How do you account for the fact that the -COOH group of the conjugate acid of alanine is a stronger acid than the -COOH group of propanoic acid?