hydrogen bonds , acting primarily through backbone peptide units , are mainly responsible for the involvement of the positively charged arginine 151 residue in the ligand site of the arabinose-binding protein , for the association between teh sulphate-binding protein and the completely buried sulphate dianion , and for the formation of the complex of the leucine/isoleucine/valine-binding protein with the leucine zwitterion .
C1317494
leucine/isoleucine/valine
C0023401
leucine