Protein Structure and Information Content 



111 



if il is found that polypeptides are chosen from a single, long master sequence 

 the value could be as low as 1 .0 bits/residue. 



Estimates of 4.5 bits per residue or greater at the structural level give a 

 total information content, /,, for the non-structural proteins in excess of 500 

 bits (or in excess of 100 bits if the minimum estimate turns out to be the true 

 one). Such an estimate is in sharp contrast to the estimates of 10 bits or less 



1000 



3 



o 



UJ 



o 



z 



o 



UJ 



m 



13 

 Z 



/RESIDUE-- 0.50 + 



30+3 \oq, R 



3 loq^ R 



Ij./ RESIDUE (IN 



Fig. 3. Limits for estimates of the minimum of 4 as a function of the number 



of residues per helix. The shaded area indicates helical polypeptide sizes reported 



by Pauling, Corey and Branson (8). 



obtained by Quastler and his co-workers (14) as the amount of information 

 which must be transmitted for the proper functioning of most protein-controlled 

 systems (e.g. enzymes, immune bodies). 



III. ESTIMATION OF STRUCTURAL INFORMATION CONTENT 



NECESSARY FOR FUNCTION 



A disparity of at least one order of magnitude or more in passing from 

 one context or level of organization to another is of considerable interest. 

 The ten-fold difference indicates that only a small part of the information 

 potential is actually utilized in information transmission. 



Does this indicate that information transmission in such systems is very 

 noisy and therefore organisms obtain good transmission by utilizing a very 

 high degree of redundancy? Dancoff (15) proposed a principle of maximum 



