. Author manuscript; available in PMC: 2013 Mar 2.

Published in final edited form as: J Proteome Res. 2012 Feb 15;11(3):1512–1520. doi: 10.1021/pr2003165

Table 4. Frequency of triplet amino acids in human proteins^a.

Triplet	Triplet Hits^α	Protein Hits^b	Frequency^c	Prevalence^d (%)
Ser-Xaa-His	38392	18591	2.07	48.8
Thr-Xaa-His^e	N/A	N/A	N/A	N/A
Tyr-Xaa-His	13121	9029	1.45	23.7
His-Xaa-Ser	36988	18271	2.02	48.0
His-Xaa-Thr	22323	13813	1.62	36.3
His-Xaa-Tyr	12871	9032	1.43	23.7

38,063 protein sequences from NCBI database were interrogated.

Number of times the given triplet was found in entire database.

Average frequency of triplet per protein hit.

Prevalence of proteins containing the triplets in entire database.

Reactivity with Thr-Xaa-His triplets was not observed although His-Xaa-Thr was likely related to the branched nature of the threonyl side-chain.

Table 4. Frequency of triplet amino acids in human proteinsa.