So far the best result I have obtained is 19 different consecutive aminoacids with a stop signal. The largest genomes are more likely to contain the full alphabet. Currently the largest genome is in a plant or tree - its genome is about 50 times larger than the human genome. It would be interesting to see if this plant holds the key.
I have amended the computer code now, so that it searches all three reading frames. It translates the codons in the first reading frame into the corresponding 22 amino acids, then searches for a string of 22 different consecutive amino acids. On completion it translates the second reading frame into the corresponding amino acids, then searches for a string of 22 different consecutive amino acids. Finally it does the same for the third reading frame.
I am running it on a slower computer that is less likely to get overheated. It will take about 200 hours to complete the entire Y Chromosome and 600 hours (approx 1 month) to complete the entire X Chromosome - with the computer running 24 hours. I have delegated one computer completely for this task, and this task only. This means that I can get on with investigating other ideas on my other computers.