TABLE 24-2 The Standard Amino Acids(continued) Functional Group lsoelectric Name Symbol Abbreviation Structure in Side Chain Point tyrosine Tyr H,N一CH-COOH phenolic-OH group 5.7 CH, OH side chain contains sulfur cysteine c Cys H,N-CH-COOH thiol 5.0 CH,-SH methionine W Met H,N-CH-COOH sulfide 5.7 CH一CH一S-CH side chain contains nonbasic nitrogen asparagine N Asn HN-CH一COOH amide 5.4 CH2-C-NH2 0 glutamine GIn H,N-CH-COOH amide 5.7 CH,一CH C一NH tryptophan W Trp H,N-CH-COOH indole 5.9 H H Chapter 24 9Chapter 24 9