Trypsin is a digestive enzyme that hydrolyzes peptide bonds only when the carbonyl group in the amide bond comes from lysine or arginine. Draw the structure of the amino acids and peptides formed by hydrolysis of the following peptide with trypsin: Gly-Lys-Arg-Ala-Ala-Arg Draw the structure of the amino acid phenylalanine at a pH of 1.

the overall, net ionic charge on this peptide at pH = 7 would be: Cys - Ala - Glu-Arg - Met - Ser

At what pH can you separate the following peptides: ala-ala-ala, glu-glu-glu, his-his-his? OA 2.0 B. 4.0 C. 5.0 O D. 7.0 E. 9.5

1) Indicate the total charge of the peptide at pH 7.0, 9.0, and 11.0 2) Determine the isoelectric point (pI) for this peptide. Show the relevant pKa’s and your calculation.  3) What is the fraction of the peptide that has the N-terminal amino group deprotonated at pH 9.

A HEPTAPEPTIDE that punctures the bacterial cell wall has just been recently isolated from the venom gland of a frog. Amino acid analysis of the peptide reveals the following information below: (NOTE: when the sequence is not known, a comma separates the amino acids) Hydrezine Acid Hydrolysis (6 N HC) at 10 C Heptapeptide (2) Arg. Pro, Phe, Tyr, Ala, Lys 2,4 dinitrafluerobenzene DNP-Phe Lys and modified free amino acids Peptide 1 (Ala, Lys) Cleovage with Trypsin, then chrometogrophy Peptide 2 (Pro, Arg, Tyr) Peptide 3 (Phe, Arg) Phe Peptide 4 (Arg. Tyr) Clevege with Chymetrypsin, then cromategrphy Peptide 5 (Lys, Pro, Ala, Arg)

Draw the two dipeptides possible when glutamine and cysteine undergo dehydration to form a peptide bond. Draw the dipeptides in zwitterionic form.

Draw the Fischer projections representing the L forms of the following amino acids at pH higher than their isoelectric point. a) cysteine b) alanine