Solid-state modifications of poly(γ-ethyl-L-glutamate)

Several modification of the arrangements of α-helical molecules were found in the solid films of poly (γ-ethyl-L -glutamate), depending on the casting solvent and the temperature. The helical conformation is somewhat looser than the normal 18-residue, 5-turn α-helix. Using x-ray diffraction, the types of molecular arrangements were classified into tetragonal, pseudohexagonal, and hexagonal ones. Tetragonal packing was observed in the filmm (form T) prepared by casting the solution in trifluorethanol or dichlorethane. The sample obtained from chloroform solution is a well-ordered, pseudohexagonal modification (form I). Forms I and T change into a poorly crystalline form III by annealing at temperatures above 130° C. It is particularly noteworthy that the less-ordered form III exhibits a thermoreversible transition around 110°C into a well-ordered form H with the hexagonal molecular packing.     

A Bethlem myopathy Gly to Glu mutation in the von Willebrand factor A domain N2 of the collagen alpha3(VI) chain interferes with protein folding.

A single G1679E mutation in the amino-terminal globular domain N2 of the alpha3 chain of type VI collagen was found in a large family affected with Bethlem myopathy. Recombinant production of N2 ( approximately 200 residues) in transfected mammalian cells has now been used to examine the possibility that the mutation interfered with protein folding. The wild-type form and a G1679A mutant were produced at high levels and shown to fold into a stable globular structure. Only a small amount of secretion was observed for mutants G1679E and G1679Q, which apparently were efficiently degraded within the cells. Homology modeling onto the related von Willebrand factor A1 structure indicated that substitution of G1679 by the bulky E or Q cannot be accommodated without considerable changes in the folding pattern. This suggests protein misfolding as a molecular basis for this particular mutation in Bethlem myopathy, in agreement with radioimmunoassay data showing reduced levels of domain N2 in cultured fibroblasts from two patients.     

Aid for the Choice of Buffer Concentration

The peptic hydrolysis of bovine β-lactoglobulin (β-Lg) was performed to establish the basis for producing a low-phenylalanine peptide rather than a free amino acid mixture for use in the dietetics of phenylketonuria. A 1% β-Lg solution (pH 1.5) was incubated with 0.01% pepsin at 37°C for 24 hr. The peptides produced were fractionated by high-performance liquid chromatograhy to analyze their constituent amino acids. Most of the major peptides were identified in the light of the primary structure of α-Lg to assign 31 cutting points in their protein molecule. These included cutting points at the carboxyl side of Phe-82, Phe-105 and Phe-136. This result suggests that further hydrolysis of the peptic hydrolysate of β-Lg with an exopeptidase, particularly with a carboxypeptidase, would be effective in liberating phenylalanine to produce a low-phenylalanine peptide mixture.     

Solubilization of UDP-glucose-specific starch synthetase in sweet-potato (Ipomoea batatas) starch granules by the urea/pullulanase method.

The ADP-glucose- or UDP-glucose-specific starch synthetase bound to sweet-potato (Ipomoea batatas) starch granules is localized in the granules, and the UDP-glucose-specific enzyme was solubulized by urea/pullulanase treatment of the starch granules.     

Porcine high molecular weight kininogen: its purification and properties as a thiol proteinase inhibitor as compared to human high molecular weight kininogen

1. High mol. wt kininogen (HMW kininogen) was purified to a homogeneous state from porcine plasma. 2. The protein exhibited a strong inhibitory activity for thiol proteinases such as ficin, papain and calpain I, whereas it did not inhibit serine proteinases, trypsin and chymotrypsin. 3. The mol. wt, isoelectric point, amino acid and carbohydrate compositions, stabilities to temperature and pH, kinetic constants, and immunological properties of the porcine HMW kininogen were determined and compared with those of human HMW kininogen.