(A) Yes,if we have a method to determine the sequence of amino acids in a protein,we can certainly connect this information to the purity or homogeneity of the protein.
$1$. The primary structure of a protein is defined by the specific sequence of amino acids.
$2$. Any deviation or impurity in the protein sample would result in the presence of different amino acids at the termini compared to the expected pure protein.
$3$. By identifying the $N$-terminal and $C$-terminal amino acids,we can verify if the sample matches the known sequence of the target protein.
$4$. If the terminal amino acids do not match the expected ones,it indicates that the sample is either impure or heterogeneous.
$5$. For example,in $Haemoglobin$,a single amino acid substitution in the primary structure can lead to abnormal protein function,such as in $Sickle$ $Cell$ $Anaemia$,which highlights the importance of sequence homogeneity for protein purity.