Question

Find the two other segments of the sequence among your classmates that will complete the protein. For example if you have a middle segment you will need to find a beginning and an end segment. Write the entire linear order of amino acids in Part 2, Question l in your proforma, (using the single letter amino acid abbreviation). Start with the beginning segment, followed by the middle segment and lastly, the end segment. Indicate the amino (NH2) and carboxyl (COOH) ends of the insulin protein. Number every 5th amino acid in the sequence (write the number above the appropriate amino acid: eg, 5 10 15 etc). So the number 5 goes ON TOP of the fifth amino acid, (not after it). This makes it easier to locate a particular amino acid in the sequence. How many amino acids does this complete insulin protein contain? (Yes, you have to count them!) Write this answer in your proforma. Indicate on the complete amino acid sequence (in your proforma) where the enzymes cut the prepro-insulin to remove the signal sequence and C peptide. The locations where the enzymes cut should indicated by a downward pointing arrow above the sequence. Please put this arrow between the two amino acids where these cuts occur. eg. D L A V R T Write out the amino acid sequences of the mature insulin hormone (B and A chains). Write out two separate chains. Do not unite the chains. Please write these out in the proforma. (Remember to remove the signal sequence and C peptide from the original amino acid sequence) How many amino acids are in the B chain? And how many amino acids are in the A chain? Write these figures in your proforma.

Answer 1

This question is relating to protein sequences that have been given in class to be placed in the right order.

I have attempted to answer your question assuming that the question is on Human Insulin hormone after reading the questions.

Answer: Insulin hormone is a short peptide hormone secreted by the beta cells of islet of pancreas and has 51 amino acids in the following sequence.

Signal Peptide -->B chain-->C-Ppetide-->A chain Toatl 110 polypeptides

M¹ALWM⁵RLLPL¹⁰LALLA¹⁵LWGPD²⁰PAAAF²⁵VNQHL³⁰CGSHL³⁵VEALY⁴⁰LVCGE⁴⁵RGFFY⁵⁰TPKYR⁵⁵REAED⁶⁰LQVGQ⁶⁵VGLGG⁷⁰GPGAG⁷⁵SLQPL⁸⁰ALEGS⁸⁵LQKRG⁹⁰IVEQC⁹⁵CTSIC¹⁰⁰SLYQL¹⁰⁵ENYCN¹¹⁰

The polypeptide is cleaved at 24th, 55th and 56th and 88th and 89th position to separate the unwanted components leaving behind the Insulin Hormone

A Chain Gly lle Val Glu Gin Cys Cys Ala Ser Val Cys Ser Leu Tyr Gin Leu Glu Asn Tyr Cys Asn Phe Val Asn Gln His Le Cys Gly Ser His Leu Val Glu Ala Leu Tyr eu Val Cys Gly Glu B Chain Arg Gly Phe Ala Lys Pro Thr Tyr Phe

In Chain A-21 amino acids -The NH₂ terminal is Gly and COOH terminal is Asn

In Chain B-30 amino acids-The NH₂ terminal is Phe and COOH terminal is Ala