Chapter 6, Problem 1P

Interpretation Introduction

Interpretation: The score for the given alignment is to be calculated using the identity-based scoring system. Also, whether the given proteins are related to each other or not is to be identified.

Concept introduction: Proteins are the biomolecules which are composed of the long chain of amino acid residues. The identical sequences or the primary structure in nucleic acids or proteins are known as conserved sequences. The highly conserved sequences consist of RNA components of ribosomes in all kingdoms of life.

Answer to Problem 1P

The score for the given alignment is $220$ . The given proteins evolutionary related to each other and are structurally identical.

Explanation of Solution

The given alignments of proteins are shown below.

  $\begin{array}{l}\text{1}\text{. WYLGKITRMDAEVLLKKPTVRDGGHFLVTQCESSPGEF}\\ \text{2}\text{. WYFGKITRRESERLLLNPENPRGTFLVRESETTKGAY}\\ \text{ SISVRFGDSVQ-----HFKVLRDQNGKYYLWAVK-FN}\\ \text{ CLSVSDFDNAKGLNVKHYKIRKLDSGGFYITSRTQFS}\end{array}$

  $\begin{array}{l}\text{ SLNELVAYHRTASVSRTHTILLSDMNV}\\ \text{ SSLQQLVAYYSKHADGLCHRLTNV}\end{array}$

In the above alignments, there are $27$ identities and $2$ gaps. Each identity between aligned sequences results in $+10$ points. On the other hand, each gap introduced, regardless of size it results in $-25$ points. Therefore, the score for the given alignment is calculated as follows,

  $\begin{array}{c}\text{Score}=\left(27\times 10\right)-\left(2\times 25\right)\\ =270-50\\ =220\end{array}$

Hence, the score for the given alignment is $220$ .

The above two sequences has $27$ identities. Therefore, they are $27\%$ identical over almost $100$ residues. Hence, these proteins evolutionary related to each other and are structurally identical.

Conclusion

  $220$ is the score for the given alignment. The given proteins evolutionary related to each other and are identical structurally.