Question regarding Amino Acid and Protein compositions I am

Question regarding Amino Acid and Protein compositions,

I am predicting that the \"spherical\" is has the most polar aa. While the linear is in between and the subunit has more NP aa. I wanted to hear how an \"expert\" would explain this because I am unsure.

As part of an undergraduate biochemistry research project, you are characterizing three polypeptides of approximately equal molecular weight from human plasma. Using various physical techniques, you have established that in their native states one of the polypeptides is a monomeric, cigar-shaped molecule, the second is mondomeric and approximately spherical, and the third is the subunit of a tetramer of identical subunits Your lab partner has determined the amino acid compositions of the three proteins. However, when he brings you the data, shown below, you discover that he failed to note which composition corresponds to which protein. A research student at the next bench tells you that you should be able to simply deduce which is which from the amino acid compositions themselves. Your partner is sure that the research student is trying to trick you. Should you take his advice? If you decide to do so, which composition would you assign to which protein, and why? Number of residues/molecule Amino acid Protein 1 Protein 2 Protein 3 Polar residues Arg 12 Asn Asp 14 Cys Gln Glu 11 His Lys 22 15 Ser 20 21 Thr 15 11 Trp Tyr Nonpolar residues Ala 14 28 25 Gly 16 Leu 19 Met 11 Phe 11 15 Pro 13 10 Val 16 21

Solution

Protein 1 - monomer , cigar shaped - 1) when a protein has more polar aa it should be always in concact with water as it hydrophilic . 2) so the protein which contains more polar residues should be linear or cigar shaped 3) do protein 1 must be monomer with cigar shaped. Protein 2- spherical- 1)When a protein has more number of non-polar aminoacids , the protein avoids water and hence it becomes a spherical shape like micelles. 2) So the protein which contains more number of non polar aa should be monomer with spherical structure. 3) So it should be protein 2. Protein 3 - Tetramer .- Hence protein 3 is tetramer .