Final answer:
To estimate the size of the protein, calculate the total number of amino acids. Use the length of the β-strands and the number of amino acids per nm to find the total length and number of amino acids. Multiply the number of amino acids by the average molecular weight of an amino acid residue to estimate the size in kDa.
Step-by-step explanation:
To estimate the size of the protein, we need to calculate the total number of amino acids in the protein. Since each β-strand is approximately 3.7 nm long and there are 22 β-strands, the total length of the protein would be 3.7 nm x 22 = 81.4 nm.
To convert this length to the number of amino acids, we need to know the number of amino acids per nm. Since there are approximately 3.6 amino acids per turn and each turn is 5.4 Å (0.54 nm), we can calculate the number of amino acids per nm as 3.6/0.54 = 6.67 amino acids/nm. Therefore, the total number of amino acids in the protein is 81.4 nm x 6.67 amino acids/nm = 542.9 amino acids.
Finally, to estimate the size of the protein in kDa, we can multiply the number of amino acids by the average molecular weight of an amino acid residue (110 g/mol) and divide by 1000 to convert grams to kilo daltons. Therefore, the estimated size of the protein is (542.9 amino acids x 110 g/mol) / 1000 = 59.7 kDa.