title: Pancreatic spasmolytic polypeptide: crystallization, circular dichroism analysis, and preliminary X-ray diffraction studies.
abstract: Pancreatic spasmolytic polypeptide (PSP) isolated from porcine pancreas has been crystallized by the hanging drop vapor diffusion method. Crystals suitable for X-ray diffraction analysis were grown at pH 4.7 from a solution of 6% saturated ammonium sulfate. The space group is orthorhombic I222 or I2(1)2(1)2(1) with unit cell parameters a = 54.38 A, b = 72.29 A, and c = 180.85 A. There are three molecules of PSP per asymmetric unit and a water content of 46.9%. The crystals diffracts to an estimated resolution of 2.7 A. The far-UV CD spectrum of PSP shows some exceptional features which cannot be accounted for thoroughly in terms of standard secondary structures commonly seen in protein CD spectroscopy. With this limitation, the secondary structure analysis predicts 15% alpha-helix, between 10 and 20% antiparallel beta-strand, 10% parallel beta-strand, 15% turn, and 25 to 40% of other structures.
authors.affiliation: Department of Physical Chemistry, H.C. Orsted Institute, University of Copenhagen, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Gajhede
authors.forename: L
authors.initials: L
authors.lastname: Thim
authors.forename: K H
authors.initials: KH
authors.lastname: Jørgensen
authors.forename: S G
authors.initials: SG
authors.lastname: Melberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D003460:Crystallization; D036341:Intercellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009077:Mucins; D009124:Muscle Proteins; D009479:Neuropeptides; D010179:Pancreas / Q000201:enzymology*; D010276:Parasympatholytics / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013552:Swine; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3; D014961:X-Ray Diffraction
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D009077:Mucins; D009124:Muscle Proteins; D009479:Neuropeptides; D010276:Parasympatholytics; D010455:Peptides; C099037:TFF3 protein, rat; C000604008:Tff2 protein, rat; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3; C034407:pancreatic spasmolytic polypeptide