A. What is the Isoelectric point pI of the peptide Gly-Glu-Ala-Lys-Val ?
B. A purified protein is in a Hepes buffer at pH 7 with 300 mM NaCl. A sample (2mL) of the protein solution is placed in a tube made of dialysis membrane and dialyzed against 1 L of the same Hepes buffer with no NaCl. Small molecules and ions (such as Na+, Cl-, and Hepes) can diffuse across the dialysis membrane, but the protein cannot.
1. Once the dialysis has come to equilibrium, what is the concentration of NaCl in the protein sample? Assume no volume changes occur in the sample during dialysis.
2. If the original 2 mL sample were dialyzed twice, successively, against 100 mL of the same Hepes buffer with 0 mM NaCl, what would be the final NaCl concentration in the sample?
The isoelectric point pI of the peptide Gly-Glu-Ala-Lys-Val is calculated as below,
At pH 7 = net charge on the peptide is zero and the pI = 6.925
A. What is the Isoelectric point pI of the peptide Gly-Glu-Ala-Lys-Val ? B. A purified protein...
N’-Val-Asp-Ala-Lys-Glu-Gly-Ser-Glu-Gly-Met-Ser-Lys-C' as they occur at pH 8 Tell in detail how to find an isoelectric point!
Which of these protein sequences is most likely to span a cell membrane? Gly-Asp-Val-Ala-Gly-Arg-Gly-Asn-Gly-Lys-Lys-Pro-Ser-Ser-Val-Arg-Ala-Leu-Ser Ile-Val-Leu-Pro-Ile-Val-Leu-Leu-Val-Phe-Leu-Cys-Leu-Gly-Val-Phe-Leu-Leu-Trp Lys-Asn-Trp-Arg-Leu-Lys-Asn-Ile-Asn-ser-Ile-Asn-Phe-Asp-Asn-Pro-Val-Tyr-Gln A. 773 B. 792 C. 811
Met-Ala-Arg-Tyr-Ala-Asn-Asn-Glu__Lys-Glu-Leu-Leu-Tyr__Arg-Tyr-Ala-Asn__Phe-Leu-Ala-Asn-Asn-Ile-Gly-Ala-Asn__Ile-Ser__Ile-Asn-Thr-Glu-Arg-Glu-Ser-Thr-Glu-Asp__Ile-Asn__ His-Glu-Arg__Phe-Ala-Thr-His-Glu-Arg-Ser__Thr-Arg-Ile-Gly-Leu-Tyr-Cys-Glu-Arg-Ile-Asp-Glu__Leu-Glu-Val-Glu-Leu-Ser__Ser-Ile-Asn-Cys-Glu__His-Glu-__His-Ala-Pro-Pro-Ile-Leu-Tyr__Glu-Ala-Thr-Ser__Val-Ala-Asn-Ile-Leu-Leu-Ala__Cys-Ala-Lys-Glu-__Ala-Asn-Asp__Pro-Glu-Cys-Ala-Asn__Pro-Ile-Glu__Trp-Ile-Thr-His__Phe-Arg-Ile-Glu-Asp__Cys-His-Glu-Glu-Ser-Glu-Cys-Ala-Lys-Glu__Ile-Cys-Glu__Cys-Arg-Glu-Ala-Met__Glu-Val-Glu-Arg-Tyr-Asp-Ala-Tyr__Ala-Asn-Asp__Ser-His-Glu__Ile-Ser__Asp-Glu-Val-Ala-Ser-Thr-Ala-Thr-Glu-Asp__Thr-His-Ala-Thr__Asp-Ile-Ser-Glu-Ala-Ser-Glu-Ser__Leu-Ile-Lys-Glu__His-Glu-Ala-Arg-Thr__Asp-Ile-Ser-Glu-Ala-Ser-Glu__Ser-Leu-Glu-Glu-Pro__Ala-Pro-Asn-Glu-Ala__Ser-Glu-Val-Glu-Arg-Glu__Trp-Glu-Ile-Gly-His-Thr__Gly-Ala-Ile-Asn__Trp-Ile-Leu-Leu__Ala-Arg-Ile-Ser-Glu__Ile-Phe__His-Glu__Lys-Glu-Glu-Pro-Ser__Thr-His-Ile-Ser__Glu-Ala-Thr-Ile-Asn-Gly__Pro-Ala-Thr-Thr-Glu-Arg-Asn__Tyr-Glu-Thr__Ile-Phe__His-Glu__Trp-Trp-Trp-Trp-Ile-Ile-Ile-Ile-Ile-Leu-Leu-Leu-Leu-Leu-Ser-Ser-Ser-Ser__Cys-His-Ala-Asn-Gly-Glu__Ile-Asn__His-Ile-Ser__Leu-Ile-Phe-Glu-Ser-Thr-Tyr-Leu-Glu__His-Glu__Cys-Ala-Asn__Ser-Thr-Ile-Leu-Leu__Arg-Glu-Met-Ala-Ile-Asn__His-Glu-Ala-Leu-Thr-His-Tyr__Ser-Ala-Ser-Ser-Tyr__Ala-Asn-Asp__Ala-Leu-Arg-IleGly-His-Thr 1.) Write out the 1 letter amino acid abbreviation for each of the three-letter amino acid abbreviated words listed in the given sequence. The __ indicates a space in between the words. Use www.expasy.org and other bioinformatic tools to generate the following bioinformatic data for the given polypeptide sequence. You must give the name and link to the program you used to generate the data: 2.) Compute the pI and Mw (isoelectric point and molecular mass, respectively) of...
help with these please Examine the peptide. Thr-Glu-Pro-Ile-Val-Ala-Pro-Met-Glu-Tyr-Gly-Lys Write the sequence using one-letter abbreviations. sequence: TKPIVAPMEYGK Estimate the net charge on the peptide at pH 7. charge at pH 7: Estimate the net charge on the peptide at pH 12. Alpha helices are a type of secondary structure in proteins. What is the length of a 23.0 kDa single-stranded a-helical protein segment? Assume a mean residue mass of 110 Da. length: Beta () sheets are a type of secondary structure...
The isoelectric point (pI) of a peptide is the pH at which the peptide does not migrate in an electric field. Since the peptide is zwitterionic, there are the same number of positive charges as negative charges on the peptide population. The pI can be estimated fairly accurately (within 0.1 or 0.2 pH units) from the pK values of all the proton dissociable groups in the peptide. Using pK values from the table at the right, estimate the pI value...
The isoelectric point (pI) of a peptide is the pH at which the peptide does not migrate in an electric field. Since the peptide is zwitterionic, there are the same number of positive charges as negative charges on the peptide population. The pI can be estimated fairly accurately (within 0.1 or 0.2 pH units) from the pK values of all the proton dissociable groups in the peptide. Using pK values from the table at the right, estimate the pI value...
10. The peptide shown has the amino acid sequence: A. Val-Ser-Ile-Glu-Lys B. Lys-Glu-Ile-Ser-Val C. Thr-Asp-Leu-Gln-Arg D. Val-Asp-Ile-Glu-Arg 11. Which of the following describes the entire three- dimensional structure of a single polypeptide? A. Secondary structure B. Quaternary structure C. Tertiary structure D. Primary structure 12. What is the primary driving force in the formation of protein tertiary structure? A. Energy released when additional ion pairs are formed. B. The exclusion of non-polar substances from aqueous solution. C. The formation of...
A protein has the following N-terminal sequence and the following organization of signal/stop/start sequences. Met-Lys-Trp-Val-Thr-Phe-Leu-Leu-Leu-Leu-Phe-Ile-Ser-Gly-Ser-Ala-Phe-Ser-Arg-… i) What is the topology of this protein in the cell membrane? The red segments correspond to either signal sequences or stop transfer sequences. The orange segments correspond to start transfer sequences ii) What is the N-terminal sequence of the protein, after processing iii) Is this a eukaryotic or prokaryotic protein? Why? Signal Stop Start Stop Start
5. Consider the following peptide: His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys-Tyr-Leu-Asp-Ser-Arg-Arg-Ala-Gin- Asp-Phe-Val-Gln-Trp-Leu-Met-Asn-Thr a. What are the fragments, if it is cleaved by trypsin? b. What are the fragments, if it is cleaved by chymotrypsin? c. What are the fragments, if it is cleaved by pepsin?
From Hung et al., (2017) “Purification,characterization and biological effect of lectin from the marine sponge Stylissa flexibilis (Lévi, 1961)” Specimens were cut into small pieces, ground with a mixer machine and extracted (1:2, w/v) with 50 mM Tris–HCl, 150 mM NaCl buffer (pH 7.5) for 6 h at 4 °C. After filtration through a cheese cloth, the filtrate was centrifuged at 3500 × g for 30 min at 4 °C. To the supernatant, cold absolute ethanol (− 20 °C) was...