asn3key

BICH 409 Spring 2024 Assignment 3 100 pts Key 1.) Consider the following peptides: (a) Cys-Val-Asp-Asn-Leu (b) Arg-Gly-Ala-Phe-Met (c) Leu-Val-Ser-Asn-Trp (d) Tyr-Glu-Gln-Asp-Pro (e) Lys-Phe-Ile-His-Arg a.) ( 3 pts) Which one of the peptides would have the greatest solubility at pH 1? (e) b.) ( 3 pts) What would be the order of elution off of an anion exchange column with a pH of 7? First off-_e-b-c-a-d___________________-last to elute c.) ( 3 pts) What would be the order of elution off a cation exchange column at a pH of 7? First off-___d-a-c-b-e______________________________-last to elute 2.)(12 pts) Use the following information: Protein Molecular Weight pI (a) Homoserine Dehydrogenase 229,000 Daltons 5.50 (b) Heparin Lyase 43,150 Daltons 8.90 (c) Sortase A 24,810 Daltons 6.20 (d) Pyruvate Phosphate Dikinase 110,000 Daltons 8.25 (e) Phosphopentose Mutase 65,000 Daltons 4.85 a.) If the preceeding proteins were separated by gel filtration, what would be the order of elution? First off-__a-d-e-b-c____________________________________-last to elute b.) If the preceeding proteins were separated by isoelectric focusing then what would be the order of migration (Cathode (-)  (+) anode)? Cathode-____b-d-c-a-e_________________-Anode c.) If the preceeding proteins were separated by cation exchange chromatography at pH 7, what would be the order of elution? First off-__e-a-c-d-b___________________________- last to elute d.) If the preceeding proteins were separated by SDS-PAGE, what would be the order of migration from the top to the bottom of the gel? Top-____ a-d-e-b-c _______________________-bottom 3.) ( 12 pts) Draw out the products of the following reactions by the indicated agents. A.) Ser-Ala-Phe-Lys-Pro by trypsin → Ser-Ala-Phe-Lys-Pro B.) Thr-Cys-Gly-Met-Asn by elastase → Thr-Cys-Gly + Met-Asn C.) Leu-Arg-Gly-Asp -Met-Pro by cyanogen bromide → Leu-Arg-Gly-Asp -Met + Pro D.) Val-Trp-Lys-Pro-Arg-Glu by chymotrypsin → Val-Trp + Lys-Pro-Arg-Glu E.) Ile-Lys-Lys-Trp-Arg-Gly-Phe by trypsin → Ile-Lys + Lys + Trp-Arg + Gly-Phe F.) Ser-Leu-Lys-Ala-Gln-Arg by Carboxypeptidase B → Ser-Leu-Lys-Ala-Gln + Arg

BICH 409 Spring 2024 Assignment 3 100 pts Key 4.) ( 5 pts) A polypeptide is subjected to the following degradative techniques resulting in polypeptide fragments with the indicated amino acid sequences. What is the amino acid sequence of the entire polypeptide? I. Cyanogen bromide treatment: II. Trypsin hydrolysis: 1. Asp-Ile-Lys-Gln-Met 5. Gln-Met-Lys 2. Lys 6. Gly-Met-Asp-Ile-Lys 3. Lys-Phe-Ala-Met 7. Phe-Ala-Met-Lys 4. Tyr-Arg-Gly-Met 8. Tyr-Arg K-CBF2 FAMK-TF7 KFAM –CBF3 QMK-TF5 DIKQM-CBF1 GMDIK-TF6 YRGM-CBF4 YR-TF8 YRGMDIKQMKFAMK 5.)( 5 pts) A purified neuropeptide contains 7 residues. (a) An aliquot of the neuropeptide was treated it with dansylchloride at a pH of 8.0. Hydrochloric acid was then added lowering the pH to 1 and the solution was boiled for one hour. The only dansylated product is shown below. N H 3 C H 3 C S O O H N C C OH CH 2 H O O (b) An aliquot of the neuropeptide was treated with hydrochloric acid lowering the pH to 1 and the solution was boiled for one hour. The pH was then adjusted to 8.0 followed by treatment with dansylchloride. This procedure generated dansylaspartate, dansylisoleucine, dansylarginine, dansylmethionine, dansyltyrosine and dansyltryptophan. (c) Treatment of the neuropeptide with trypsin had no effect. (d) Brief treatment of the neuropeptide with chymotrypsin generates tyrosine, a dipeptide and a tetrapeptide. The tetrapeptide was composed of Ile, Arg and Met. (e) Treatment of the neuropeptide with cyanogen bromide generates a dipeptide, a tetrapeptide and free arginine. Based on the above information, what is the sequence of this heptapeptide? YDWMIMR

BICH 409 Spring 2024 Assignment 3 100 pts Key Use the following peptide to answer Questions 14 –21 (R) O N H (S) H H 2 C O N (S) H H 2 C H O N H (S) H O O - N H 2 C H H O (S) N H H H S O - CH 2 C O O CH 2 CH 2 CH 2 NH C NH 2 NH H 2 C O - 14.) The pH which would correspond to the ionization of the peptide as drawn above is (A) pH 1.0. (B) pH 4.0. (C) pH 7.0. (D) pH 12.0. (E) pH 14. 15.) What is the sequence of the peptide using one letter abbreviations?___SCYER_________________________ 16.) Draw the structure of the products of the trypsin catalyzed reaction with this peptide at pH 7.

BICH 409 Spring 2024 Assignment 3 100 pts Key 17.) Draw the structure of the products of the elastase catalyzed reaction with this peptide at pH 7. (R) O N H (S) H H 2 C O N (S) H H 2 C H O N H (S) H O O - H 3 N H 2 C H O (S) H 3 N H SH OH CH 2 C O O CH 2 CH 2 CH 2 NH C NH 2 NH 2 H 2 C OH O - 18.) Draw the structure of the products of the chymotrypsin catalyzed reaction with this peptide at pH 7.