Quiz 2 Answers.pdf - Ques!on 1(1 point Use the values I...

  • No School
  • AA 1
  • 8
  • 100% (1) 1 out of 1 people found this document helpful

This preview shows page 1 out of 8 pages.

You've reached the end of your free preview.

Want to read all 8 pages?

Unformatted text preview: Ques!on 1 (1 point) Use the values I told you to memorize to calculate the pI of the pep!de Arg-Glu-Lys-AspSer-Tyr. Choose the closest answer. 3. 4.0 11.5 5.8 Ques!on 2O(1 point) 9.5 H3NUse CH the O H N pI tool C CH expasy O CH2 O H H H N N CH in C CH toC findNthe CH pI of Cthe pep!de the previous CH/web.expasy.org/compute_pi/ CH2 CH2 2 h"ps:/ CH2 O CH2 CH2 C CH2 O H N C problem. CH O 2.2 C OH CH2 OH CH2 single le"erCabbrevia!ons O CH OH use the for2 the amino acids. NH C NH OH CH2 4.1 NH3 3.9 NH3 following information to answer the next 4 questions. Use the 10.5 OH 10.5 The sequences given below use the single letter abbreviations for the amino acids in the 12.5 sequence. You can look those up in the lecture notes. +3 à +2 à +1 à 0 à -1 à -2à -3 à -4 You are sequencing a protein. The trypsin digest gives you the following peptides. the pI is the average of the pKa values when the charge on the protein goes from +1 to 0 (4.1) and 0 to -1 ( 9.5) . The average is 6.8, the closest answer is 5.8. ECPGK AAAIIER QEWPELVGEYGYK ENPNVR AR 11.5 5.8 Ques!on 2 (1 point) Use the expasy pI tool to find the pI of the pep!de in the previous problem. h"ps://web.expasy.org/compute_pi/ use the single le"er abbrevia!ons for the amino acids. Use the following information to answer the next 4 questions. The sequences given below use the single letter abbreviations for the amino acids in the sequence. You can look those up in the lecture notes. You are sequencing a protein. The trypsin digest gives you the following peptides. ECPGK AAAIIER QEWPELVGEYGYK ENPNVR AR Use the following information to answer the next 4 questions. The sequences given below use the single letter abbreviations for the amino acids in the sequence. You can look those up in the lecture notes. You are sequencing a protein. The trypsin digest gives you the following peptides. ECPGK AAAIIER QEWPELVGEYGYK ENPNVR AR SIVKHER The chymotrypsin digest is GY PELVGEY KAAAIIERENPNVRSIVKHER ARECPGKQEW ARECPGKQEW KAAAIIERENPNVRSIVKHER QEWPELVGEYGYK ARECPGKQEWPELVGEYGYKAAAIIERENPNVRSIVKHER here are the results of the blast search The correct answer was trypsin inhibitor [Amaranthus hypochondriacus] I accepted most answers that included the words trypsin inhibitor. Amaranthus hypochondriacusis the name of the organism, not the protein. Ques!on 5 (1 point) trea!ng the protein with cyanogen bromide would yield useful informa!on for the determinig the sequence. This is false, There are no methionine residues in the protein so it will not cleave and will therefore not yield any additional information. Ques!on 6 (1 point) What is the N terminal residue ALA Ques!on 7 (1 point) The sequence given is a fragment of the protein. How many amino acids are in the intact protein? 76 before this method was available, animal insulin was used instead. Ques!on 6 (1 point) Insulin consists of two polypeptide chains, an A chain and a B chain, joined together by disulfide bonds. smaller of the two chains is referred to as the A chain and is 21 amino acids long in humans. WhatThe is the N terminal residue The second chain is referred to as the B chain and is 30 amino acids long in humans. Insulin from various animals is similar to, but not identical to human insulin, as illustrated in Table 4.1. A schematic Ques!on point) of insulin is shown in Figure 4.1. diagram of 6the(1structure ALA What is the N terminal residue Table 4.1: Variation in positions A8, A9, A10, B1, B2, B27 and B30 of insulin. (All other amino acids are the same.) ASN Species ALA human ASP A8 A9 A10 B1 B2 B27 B30 Thr Ser Ile Phe Val Thr Thr Ala Ser Val Phe Val Thr Ala Thr Ser Ile Phe Val Thr Ala Thr Gly Ile Phe Val Thr Ala Ques!on ARG 7 (1 point)Thr rabbit Ser Ile Phe Val Thr Ser ASN cow ARG pig ASP horse The sequence given is a fragment the protein. acids are dog Thr Ser of Ile PheHow many Val amino Thr Alain the intact protein? chicken Asn Thr Ala Ala Ser Ala Ques!on 7 (1 point) His Asn of the Pro protein.AlaHow many AlaaminoSer Theduck sequence givenGlu is a fragment acids areThr in the intact protein? 1 Ques!on 8 (1 point) Look at the sequences of the A and B chains of inuslin in case 4 and decide which of the following animals has the sequence that most closely resembles the human sequence. Ques!on 8 (1 point) LookDuck at the sequences of the A and B chains of inuslin in case 4 and decide which of the following animals has the sequence that most closely resembles the human sequence. Dog Duck Pig Dog Rabbit Pig Chicken Rabbit Rabbit is the Ques!on 9 (1closest point) to human. It differs only at position B30. Ser is closer to Chicken thr than ala. Based on what you know about the structures of the amino acids, which of the sequences of the A and B chains shown in case 4 is most likely to differ in structure from the human Ques!on 9 (1 point) Based on what you know about the structures of the amino acids, which of the sequences of the A and B chains shown in case 4 is most likely to differ in structure from the human pig duck rabbit Duck and Chicken, the only non mammals in the list, are the most different. The chicken Pro at position A10 of the duck sequence would most likely cause the greatest horsein structure difference Ques!on 10 (1 point) In anyway you deem interes!ng look up the 3 dimensional structure of insulin. How many of what type of secondary structure elements are in the structure of the monomeric form of the protein protein? 2 an! parallel beta sheets 4 strands each 3 alpha helices 2 disulfide bonds 2 stranded parallel beta sheet between monomers none of the above Ques!on 11 (1 point) In this picture caninsulin see Look at the sequences of the A and B chains of insulin and determine which you of the proteins shown would have a pI no!cably different from the the human protein? three alpha helices and 1 beta strand, not all version have the beta strand so 3 alpha helices is the most correct answer to this question 2 stranded parallel beta sheet between monomers none of the above Ques!on 11 (1 point) Look at the sequences of the A and B chains of insulin and determine which of the insulin proteins shown would have a pI no!cably different from the the human protein? Horse Dog Pig Cow Chicken Horse le abo Looking at the table above, duck and chicken will both have different isoelectric points because Dog Ques!on 12 at (1position point) A8 and Duck has a GLU while the human protein has a THR. It is chicken has a HIS hard to predict which will be the most different. But in this case duck is not one of the choices. Look Pigat the sequences of the A and B pep!des of the different insulins. Why are the sequences of the chicken and duck so much different than the other seqeunces? HUMAN 5.19 chicken 6.74 Cow duck 4.00 Ducks and chickens don't metabolize glucose Chicken These are the numbers I calculated for a peptide with the residues shown in the table, Chicken Ducks and chickens are more closely related to humans than the other species is more different than duck from human using the expasy compute pI tool Ducks and chickens are not mammals Ques!on 12 (1 point) There is no ra!onal explana!on Look at the sequences of the A and B pep!des of the different insulins. Why are the sequences of the chicken and duck so much different than the other seqeunces? Ques!on 13 (1 point) Ducks and chickens don't metabolize glucose Experiments in which proinsulin is unfolded and refolded in the presence of Ducks and chickens are more closely related to humans than the other species betamercaptoethanol and then cleaved yield almost 100% ac!vity. Experiments in whi Ducksinsulin and chickens are not and mammals mature is unfolded refolded in the presence of beta mercaptoethanol yielde approximately 10% of the ac!ve insulin. Which of the following best explains there There is no ra!onal explana!on results? Ques!on 13 (1 point) Differences in the way the mature and proinsulin molecules fold. Experiments in which proinsulin is unfolded and refolded in the presence of betamercaptoethanol and then cleavedform yieldin almost 100% ac!vity. Experiments in which The disulfide bonds cannot the intact proinsulin molecule. mature insulin is unfolded and refolded in the presence of beta mercaptoethanol yielded approximately 10% of the ac!ve insulin. Which of the following best explains there The results are wrong because the disulfide bonds can only form one way. Ducks and chickens are more closely related to humans than the other species Ducks and chickens are not mammals There is no ra!onal explana!on Ques!on 13 (1 point) Experiments in which proinsulin is unfolded and refolded in the presence of betamercaptoethanol and then cleaved yield almost 100% ac!vity. Experiments in which mature insulin is unfolded and refolded in the presence of beta mercaptoethanol yielded approximately 10% of the ac!ve insulin. Which of the following best explains there results? Differences in the way the mature and proinsulin molecules fold. The disulfide bonds cannot form in the intact proinsulin molecule. The results are wrong because the disulfide bonds can only form one way. The answer is the differences in the way the mature and proinsulin fold. Proinsulin is a single polypeptide. When it unfolds and refolds it always forms the same 3D structure. Mature insulin is 2 polypeptide chains held together by disulfide bonds. When the mature protein is unfolded and allowed to refold there is nothing to constraint the positions of the two chains relative to each other. Each chain will for the correct structure but the disulfides between the 2 will be random. ...
View Full Document

  • Fall '19
  • Duck

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture