On the other hand...
Petsko
G A
GA
D000596:Amino Acids / Q000737:chemistry; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism; D007839:Functional Laterality; D016333:HIV Protease / Q000138:chemical synthesis / Q000737:chemistry*; D006801:Humans; D007536:Isomerism; D011487:Protein Conformation
D000596:Amino Acids; D004798:Enzymes; D016333:HIV Protease