Search

A copolymeric stationary phase, consisting of a chiral selective part, i.e. (1R-trans)-N,N'-1,2-cyclohexylenebisbenzamide, and an efficient siloxane oligomeric part, was successfully applied to open tubular column GC analysis. The efficiency and the chiral selectivity of this stationary phase were studied in detail, and high capacity and efficiency at elevated GC temperatures were especially noted. Several drugs and other enantiomeric pairs were separated. The shown examples demonstrate a broad application range for this type of chiral stationary phase in GC analysis.

A new class of chiral copolymers consisting of chiral organic and dimethylsiloxane units is described. One example of such copolymers, containing alternating diamide and dimethylsiloxane units, has been synthesized. Using these chiral materials as stationary phases in capillary columns, chiral diols can be efficiently resolved by supercritical fluid chromatography.

A new class of chiral copolymers consisting of chiral organic and dimethylsiloxane units is described. One example of such copolymers, containing alternating diamide and dimethylsiloxane units, has been synthesized. Using these chiral materials as stationary phases in capillary columns, chiral diols can be efficiently resolved by supercritical fluid chromatography.

A new polar polysiloxane stationary phase for capillary column gas chromatography containing 4-(methylsulfonyl)phenyl substitution was synthesized and compared to a cyanophenylpolysiloxane, OV-225. The sulfonylphenylpolysiloxane phase was useful and stable over a wide temperature range from 70°C to 320°C, and it exhibited similar overall polarity to OV-225. However, because of the specific chemical properties of the 4-(methylsulfonyl)phenyl group, this phase demonstrated unique selectivities for certain classes of compounds including basic nitrogen heterocycles and polychlorinated biphenyls.

A copolymeric stationary phase, consisting of a chiral selective part, i.e. (1R-trans)-N,N'-1,2-cyclohexylenebisbenzamide, and an efficient siloxane oligomeric part, was successfully applied to open tubular column GC analysis. The efficiency and the chiral selectivity of this stationary phase were studied in detail, and high capacity and efficiency at elevated GC temperatures were especially noted. Several drugs and other enantiomeric pairs were separated. The shown examples demonstrate a broad application range for this type of chiral stationary phase in GC analysis.

The diverse forms of protein phosphatase 1 in vivo result from the association of its catalytic subunit (PP1c) with different regulatory subunits, one of which is the G‐subunit (G M ) that targets PP1c to glycogen particles in muscle. Here we report the structure, at 3.0 A resolution, of PP1c in complex with a 13 residue peptide (G M[63–75] ) of G M . The residues in G M[63–75] that interact with PP1c are those in the Arg/Lys–Val/Ile–Xaa–Phe motif that is present in almost every other identified mammalian PP1‐binding subunit. Disrupting this motif in the G M[63–75] peptide and the M 110[1–38] peptide (which mimics the myofibrillar targeting M 110 subunit in stimulating the dephosphorylation of myosin) prevents these peptides from interacting with PP1. A short peptide from the PP1‐binding protein p53BP2 that contains the RVXF motif also interacts with PP1c. These findings identify a recognition site on PP1c, invariant from yeast to humans, for a critical structural motif on regulatory subunits. This explains why the binding of PP1 to its regulatory subunits is mutually exclusive, and suggests a novel approach for identifying the functions of PP1‐binding proteins whose roles are unknown.

We have previously isolated a form of protein phosphatase-1 (PP1M) from avian smooth muscle myofibrils that is composed of the catalytic subunit of PP1 (PP1C) bound to an M-complex consisting of 110-kDa (M110) and 21-kDa (M21) subunits. The interaction of PP1C with an N-terminal region of the M110 subunit enhances the dephosphorylation of myosin and suppresses the dephosphorylation of other substrates [Alessi, D. R., MacDougall, L. K., Sola, M. M., Ikebe, M. & Cohen, P. (1992) Eur. J. Biochem. 210, 1023–1035; Chen, Y. H., Chen, M. X., Alessi, D. R., Campbell, D. G., Shanahan, C, Cohen, P. & Cohen, P. T. W. (1994) FEES Lett. 356, 51–6; Johnson, D. R, Moorhead, G., Caudwell, F. B., Cohen, P., Chen, Y. H., Chen, M. X. & Cohen, P. T. W. (1996) Eur. J. Biochem. 239, 317–325]. In this paper, we establish that PP1M accounts for nearly all the myosin phosphatase activity in myofibrils, that the M110 and M21 subunits are present at similar concentrations in the myofibrillar fraction, and that these subunits are entirely bound to PP1. We demonstrate that the M21 subunit does not interact with PP1C, but with the C-terminal 72 residues of the M110 subunit, a region which is 43% identical to residues 87–161 of the M21 subunit. A fragment of the M21 subunit, M21-(M1-L146), which lacks the C-terminal leucine zipper, also bound to the M110 subunit, but two other fragments M21-(M1-E110) and M21-(E110–K186) did not. The M110 and M21 subunits were both found to be myosin-binding proteins. The C-terminal 291 residues of the M110 subunit, but not the C-terminal 72 residues, bound to myosin, but the N-terminal fragments M110-(M1-E309) and M110-(M1-S477) did not. Thus, the region of the M110 subunit that stimulates the dephosphorylation of myosin by PP1C is distinct from the region that targets PP1M to myosin. Remarkably, each myosin dimer was capable of binding about 20 mol M21 subunit and many of the M21-binding sites were located in the myosin rod domain. The potential significance of this observation is discussed.

The specificity of the catalytic subunit of protein phosphatase-1 (PP1c) is modified by regulatory subunits that target it to particular subcellular locations. Here, we identify PP1c-binding domains on GL and GM, the subunits that target PP1c to hepatic and muscle glycogen, respectively, and on M110, the subunit that targets PP1c to smooth muscle myosin. GM-(G63-T93) interacted with PP1c and prevented GL from suppressing the dephosphorylation of glycogen phosphorylase, but it did not dissociate GL from PP1c or affect other characteristic properties of the PP1GL complex. These results indicate that GL contains two PP1c-binding sites, the region which suppresses the dephosphorylation of glycogen phosphorylase being distinct from that which enhances the dephosphorylation of glycogen synthase. At higher concentrations, GM-(G63-N75) had the same effect as GM-(G63-T93), but not if Ser67 was phosphorylated by cyclic-AMP-dependent protein kinase. Thus, phosphorylation of Ser67 dissociates GM from PP1c because phosphate is inserted into the PP1c-binding domain of GM. M110-(M1-E309) and M110-(M1-F38), but not M110-(D39-E309), mimicked the M110 subunit in stimulating dephosphorylation of the smooth muscle myosin P-light chain and heavy meromyosin in vitro. However, in contrast to the M110 subunit and M110-(M1-E309), neither M110-(M1-F38) nor M110-(D39-E309) suppressed the PP1c-catalysed dephosphorylation of glycogen phosphorylase. These observations suggest that the region which stimulates the dephosphorylation of myosin is situated within the N-terminal 38 residues of the M110 subunit, while the region which suppresses the dephosphorylation of glycogen phosphorylase requires the presence of at least part of the region 39-309 which contains seven ankyrin repeats. M110-(M1-F38) displaced GL from PP1c, while GM-(G63-T93) displaced M110 from PP1c in vitro. These observations indicate that the region(s) of PP1c that interact with GM/GL and M110 overlap, explaining why different forms of PP1c contain just a single targetting subunit.

The Society for the History of Psychology (SHP) serves to foster an awareness of and appreciation for the history of psychology among members of the American Psychological Association (APA) and other scientists, scholars, and teachers. SHP, which is Division 26 of the APA and formerly named History of Psychology, was organized first and foremost to encourage original scholarship in the history of psychology. However, the division is also committed to extending awareness of that history to the psychological community in order to foster a better understanding of the aims of contemporary psychology, its relation to other scientific and scholarly fields, and its role in society. Keywords: history of psychology; psychology history; psychology organization

A series of oligoethylene oxide-containing polysiloxanes were prepared by hydrosilylating the appropriate oligoethylene oxide-containing alkene onto a well-defined polymethylhydrosiloxane polymer. The most convenient oligoethylene oxide-containing alkenes were prepared from eugenol and the tosylate of di- or triethylene glycol monomethyl ether. The polysiloxane phase prepared from 1-(4-allyl-2-methoxyphenoxy)-5-methoxy-3-oxapentane was found to possess desirable chromatographic properties when used in capillary supercritical-fluid chromatography and is suggested as a substitute for Carbowax 20 M . The phase was usable at temperatures from 20°C to 300°C. The synthetic rationale and the effects of structural changes in the polymers on chromatographic performance are discussed in this paper. This paper also contains a systematic study of the influence of chemical structure on chromatographic properties of the resulting polysiloxane phases.

Myosin is dephosphorylated by distinct forms of protein phosphatase 1 (PP1) in smooth muscle and skeletal muscle that are composed of PP1 complexed to different regulatory subunits. The smooth muscle myosin phosphatase (smPP1M) has been characterised previously and is composed of PP1β complexed to M110 and M21 subunits that enhance the dephosphorylation of smooth muscle myosin, but not skeletal muscle myosin. In contrast, the regulatory subunit(s) of skeletal muscle myosin phosphatase (skPP1M) greatly enhance(s) the dephosphorylation of skeletal muscle myosin. Here we identify a regulatory subunit of skPP1M as the product of the MYPT2 gene, a protein whose sequence is 61% identical to the M110 subunit of smPP1M. Surprisingly, the M21 subunit of smPP1M appears to be produced from the same gene that encodes MYPT2.

Thirty muteins* of interleukin-2 were studied by reversed-phase high-performance liquid chromatography in a gradient mode. Values of the stoichiometry-factor Z [from Geng and Regnier, J. Chromatogr., 296 (1984) 15] varied over a 2.5-fold range for these proteins of similar molecular weight and composition. It is proposed that the more hydrophobic and/or more stable proteins have smaller values of Z while the larger Z-values correspond to a higher degree of protein unfolding during reversed-phase retention. The practical utility of this approach was demonstrated when these Z values were used to predict correctly a reversal in elution order for two closely related interleukin-2 muteins, when shallower gradients were used.