title: Synthesis of low-phenylalanine polypeptides.
abstract: Low-phenylalanine-peptides for dietotherapy of phenylketonuria (PKU) were prepared from soybean protein isolate. Soluble fraction of soybean protein isolate was hydrolysed by alpha-chymotrypsin then followed by carboxypeptidase-A. Molecular weight distribution and amino acid analysis were made on the resultant polypeptides. The chymotrypsin hydrolysate was divided into two fractions, Fraction I (molecular weight greater than 2500) and Fraction II (molecular weight between 1000 and 2500). The phenylalanine content of Fraction I (3.1%) was lower than that of Fraction II (5%), indicating the nonuniform distribution of phenylalanine in soy bean protein. Carboxypeptidase hydrolysis of Fraction I further reduced the phenylalanine concentration to 2.3%, approximately half of the original concentration in soybean protein isolate.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002648:Child; D002918:Chymotrypsin; D004044:Dietary Proteins; D006801:Humans; D010455:Peptides; D010649:Phenylalanine; D010661:Phenylketonurias / Q000178:diet therapy*; D010940:Plant Proteins; D013025:Glycine max
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D010455:Peptides; D010940:Plant Proteins; D010649:Phenylalanine; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002918:Chymotrypsin