title: Secondary structures of rat lipolytic enzymes: circular dichroism studies and relation to hydrophobic moments.
abstract: To explore the secondary structures of lingual and pancreatic lipases, circular dichroism measurements were performed. Maximum average ellipticities were used to calculate the percentage of alpha-helices, beta-sheets, and random coils. Lingual lipase had an ellipticity of -20235 +/- 140 deg cm2/dmol (mean +/- SE) at 220 nm suggesting 60% alpha-helix, 20% beta-sheet and 20% random coil structure, but the mean ellipticity for pancreatic lipase was -14093 +/- 82 deg cm2/dmol (mean +/- SE) at 210 nm suggesting a 34.8% alpha-helical, 25% beta-sheet and 40% random coil secondary structure. An alpha-helical stretch of residues with a large hydrophobic moment ("globular" alpha-helix by hydrophobic moment plot) from amino acids 382 through 389 at the COOH-terminal end of lingual lipase was noted. This sequence, absent in pancreatic lipase, may account for the avid binding of lingual lipase to fat emulsion particles.
authors.affiliation: Department of Medicine, George Washington University School of Medicine, DC 20037.
authors.forename: I M
authors.initials: IM
authors.lastname: Roberts
authors.forename: P
authors.initials: P
authors.lastname: Jacobson
authors.forename: J
authors.initials: J
authors.lastname: Cornette
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D008049:Lipase / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology*; D011487:Protein Conformation; D051381:Rats; D013057:Spectrum Analysis; D013552:Swine; D014059:Tongue / Q000201:enzymology*
chemical_list: D008049:Lipase