Figure 9.

The effects of individual amino acid assignments on the error minimization level of 2-letter codes similar to the code in Fig. 8a. Amino acid frequencies are shown for the random codes (see text for details) for which MP is equal to or higher than the given value. For instance, there are no codes containing Trp which with MP > 0.9, and no codes containing Tyr with MP > 0.8.