title: Physicochemical and hydrodynamic characterization of P-57, a neurospecific calmodulin binding protein.
abstract: P-57 is a neurospecific calmodulin binding protein that was discovered by virtue of its unusual interactions with calmodulin-Sepharose [Andreasen, T. J., Luetje, C. W., Heideman, W., & Storm, D. R. (1983) Biochemistry 22, 4615-4618; Cimler, B. M., Andreasen, T. J., Andreasen, K. I., & Storm, D. R. (1985) J. Biol. Chem. 260, 10784-10788]. In contrast to other calmodulin binding proteins, P-57 has higher affinity for calmodulin-Sepharose in the absence of calcium compared to that in the presence of calcium. In this study, we report the chemical and physical properties of P-57 purified from detergent-solubilized bovine brain membranes. The amino acid composition of P-57 is distinctive in that it contains a single phenylalanine residue with no other aromatic amino acids and a relatively high percentage of proline and alanine. In the presence of 0.05% Lubrol PX, its predicted secondary structure from circular dichroism spectroscopy is 1% alpha-helix, 21% beta-sheet, and 78% random coil. The hydrodynamic characteristics of the protein-detergent complex and the molecular weight of the protein were determined by gel filtration and sucrose density gradient sedimentation in the presence and absence of calmodulin. The P-57-detergent complex has an apparent Stokes radius (Rs) of 4.58 nm and a sedimentation coefficient (S20,w) of 1.44 S while the Stokes radius and S20,w for the P-57-calmodulin-detergent complex are 5.33 nm and 2.32 S, respectively. Perrin analysis of a 5-[[[(iodoacetyl)amino]ethyl]amino]-1-naphthalenesulfonic acid (AEDANS) derivative of P-57 confirmed the Stokes radius determined by gel filtration.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001923:Brain Chemistry; D002148:Calmodulin-Binding Proteins / Q000302:isolation & purification*; D002417:Cattle; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D002942:Circular Dichroism; D019922:GAP-43 Protein; D008970:Molecular Weight; D009282:Naphthalenesulfonates; D009419:Nerve Tissue Proteins / Q000302:isolation & purification*; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000596:Amino Acids; D002148:Calmodulin-Binding Proteins; D019922:GAP-43 Protein; D009282:Naphthalenesulfonates; D009419:Nerve Tissue Proteins; C006421:1,5-I-AEDANS