It sounds like you're asking about the four amino acids that are encoded by the standard genetic code, and are the building blocks of proteins. There are 20 standard amino acids, not just four. They are:

1. Alanine (Ala)

2. Arginine (Arg)

3. Asparagine (Asn)

4. Aspartic acid (Asp)

5. Cysteine (Cys)

6. Glutamine (Gln)

7. Glutamic acid (Glu)

8. Glycine (Gly)

9. Histidine (His)

10. Isoleucine (Ile)

11. Leucine (Leu)

12. Lysine (Lys)

13. Methionine (Met)

14. Phenylalanine (Phe)

15. Proline (Pro)

16. Serine (Ser)

17. Threonine (Thr)

18. Tryptophan (Trp)

19. Tyrosine (Tyr)

20. Valine (Val)

Let me know if you had something else in mind!