50 residues coded by exon 2 of chicken lysozyme carry residual catalytic activity.
The generally accepted hypothesis that exons code for fundamental polypeptide structures was tested with a fusion protein consisting of almost the entire polypeptide coded by exon 2 of chicken lysozyme fused to the N-terminus of beta-galactosidase of E.coli. Exon 2 encodes residues 28-81 of lysozyme. It thus contains Glu 35 and Asp 52, which are essential for hydrolysis of glycosidic bonds. The exon 2-beta-galactosidase fusion protein hydrolysed the substrate 4-methylumbelliferyl-N,N',N''-triacetyl-chitotrioside with a reaction rate about 1/40,000 of that of native lysozyme. The low hydrolysis rate of exon 2-peptide is partially caused by its low affinity to its substrate.
Kuchinke
W
W
Institut für Genetik, Universität zu Köln, FRG.
D000818:Animals; D002645:Chickens; D004529:Egg White; D004926:Escherichia coli / Q000235:genetics; D005091:Exons; D007700:Kinetics; D009113:Muramidase / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids
D009113:Muramidase