Primary structure of proteins

[Rolf Apweiler]

In article <32281FA9.484D at chem.ut.ee>, Andres Kreegipuu <andres at chem.ut.ee> writes:
>Hi,
>
>I am looking for information about the average occurence frecuency of
>the 20 natural amino acids in proteins. Are these data available
>anywhere?
>
>Andres Kreegipuu
>
Here some statistics from the release notes of SWISS-PROT release 33 
(52205 protein sequence entries):

                         APPENDIX A: SOME STATISTICS



   A.1  Amino acid composition

        A.1.1  Composition in percent for the complete data bank

   Ala (A) 7.54   Gln (Q) 4.02   Leu (L) 9.31   Ser (S) 7.19
   Arg (R) 5.15   Glu (E) 6.31   Lys (K) 5.94   Thr (T) 5.76
   Asn (N) 4.54   Gly (G) 6.86   Met (M) 2.36   Trp (W) 1.26
   Asp (D) 5.29   His (H) 2.23   Phe (F) 4.06   Tyr (Y) 3.21
   Cys (C) 1.70   Ile (I) 5.72   Pro (P) 4.91   Val (V) 6.52

   Asx (B) 0.001  Glx (Z) 0.001  Xaa (X) 0.02


        A.1.2  Classification of the amino acids by their frequency

   Leu, Ala, Ser, Gly, Val, Glu, Lys, Thr, Ile, Asp, Arg, Pro, Asn, Phe,
   Gln, Tyr, Met, His, Cys, Trp


I hope that will help.

Cheers


Rolf Apweiler

(SWISS-PROT Coordinator)