Frequency and Markov chain analysis of amino-acid sequences of human tumour necrosis factor

The amino-acid sequence of human tumour necrosis factor was measured according to two- and three-amino-acid sequences. The measured frequency and probability were compared with predicted frequency and probability. Of 232 two-amino-acid sequences in human tumour necrosis factor, 64 (27.586%) and 24 (10.345%) sequences can be explained by the predicted frequency and the predicted probability according to a purely random mechanism. Of 243 non-appeared two-amino-acid sequences in human tumour necrosis factor, 176 (72.428%) and 42 (17.284%) sequences can be explained by the predicted frequency and the predicted probability according to a purely random mechanism. No measured Markov transition probability matches the predicted conditional probability. No more-than-two-amino-acid sequences can be explained by a purely random mechanism.