Point-Accepted Mutation matrices

PAM Point Accepted Mutation. The PAM matrix is a frequency table representing substitution rates for closely related proteins at the particular evolutionary distance represented by multiple sequence alignments. 

Table VI shows the matrix relating the number of amino acids changed per 100 residues between any two dehydrogenases when aligned as shown in Table IV. The uncertainties in correcting for back mutations and superpositions are exceedingly great for proteins that have diverged as far as these dehydrogenases. Thus no attempt has been made to determine the number of accepted point mutations. On the other hand, if the basis...

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