Top-down analysis of protein isoprenylation by electrospray ionization hybrid quadrupole time-of-flight tandem mass spectrometry; the mouse Tgamma protein

Protein isoprenylation, an important post-translational modification with a lipid, involves the selective attachment of two types of isoprenoids, farnesyl (C15) and geranylgeranyl (C20). The isoprenoid is linked via a thioether bond to the C-terminal cysteine residue of a variety of cellular proteins, including the heterotrimeric G protein gamma-subunits. One member of the G protein family, transducin (Talpha/Tbetagamma), plays a central role in visual transduction, and the structure-function relationship has been extensively studied with purified proteins, predominantly with bovine transducin that was shown to be farnesylated at the C-terminal cysteine residue of the gamma-subunit (Tgamma). We report here the structure of the C-terminal modification of mouse Tgamma, which has not yet been elucidated owing to the low amount of protein that can be isolated from the mouse retina. Electrospray ionization mass spectrometry (ESI-MS) of the high-performance liquid chromatography (HPLC)-purified Tgamma was in good agreement with the calculated mass of the farnesylated and methylated form of mouse Tgamma (Pro1-Cys70). A 'top-down' analysis of intact Tgamma using an ESI hybrid quadrupole time-of-flight (TOF) tandem mass spectrometer provided isoprenyl-specific ions that were observed to produce ions separated by 204 Da from the conventional (unmodified) precursor ion or the C-terminal sequence ions. Such characteristic fragmentation on an isoprenoid observed in top-down analysis could be useful in general for determining the type of isoprenylation as well as probing the site of modification in the protein sequence.     

Five new steroidal glycosides,pregnedioside-A, -B,and their three monoacetates,from an Okinawan soft coral of Alcyonium sp.

Five new pregnene-type steroidal glycosides, named pregnedioside -a ($\text{1}$), 4′-O-acetyl-pregnedioside-a ($\text{2}$), 3′-O-acetyl-pregnedioside-a ($\text{3}$), pregnedioside-b ($\text{5}$), and 4′-O-acetyl-pregnedioside-b ($\text{6}$), were isolated from an Okinawan soft coral of Alcyonium sp. and their structures were elucidated. These are rare examples of steroidal gylcosides from soft coral.     

PREPARATION AND PROPERTIES OF CHLOROPHYLL/WATER-SOLUBLE MACROMOLECULAR COMPLEXES IN WATER. STABILIZATION OF CHLOROPHYLL AGGREGATES IN THE WATER-SOLUBLE MACROMOLECULE

Abstract— As an artificial model compound of the chlorophyll-protein complex in vivo , the chlorophyll/water-soluble macromolecular complexes were prepared by using synthetic linear polymers of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), and a natural polymer of bovine serum albumin (BSA). By the method described here, it is possible to prepare an aqueous chlorophyll (Chl)-macromolecular complex solution of a desired Chi aggregate, such as: Chi a (670), Chi a (740) and Chi b ; and with a desired relative content and concentration. These procedures for preparing such complexes will have wide applicability for technical use in Chi studies. For example, extremely diluted aqueous complex solutions of at least 1 × 10^-4% wt Chi a (670 or 740)-macromolecular complex / wt can be obtained without changing the spectral features. From viscosity measurements, the structures of the complexes were inferred: (1) for a linear macromolecular (PVA or PVP) complex, a Chi species is tightly surrounded by a chain of the polymer causing shrinkage of the chain; (2) globular BSA molecules surround Chi species to form a large complex. The mechanism of stabilization of Chi aggregates in thylakoid membrane was discussed concerning an analogy to the complexes studied here.     

Surface,thermal and mechanical characteristics of polymeric solids

Surface molecular motions of amorphous polymeric solids have been directly measured on the basis of lateral force microscopic (LFM) and scanning viscoelasticity microscopic (SVM) measurements. SVM measurement revealed that the molecular motion at the surface of the monodisperse polystyrene (PS) film with Mn less than ca.30k was fairly activated compared with that in a bulk region, mainly due to the surface segregation of chain end groups. Temperature dependent LFM and SVM measurement revealed that the surface glass transition temperature, Tg of the monodisperse PS film was lower than the bulk one, even though Mn was fairly large as 140k and also, that the time-temperature superposition was applicable to the surface relaxation process. The chain end group segregation at the air/PS interface was verified from the dynamic secondary ion mass spectroscopic (DSIMS) depth profiling of the proton and deuterium ion for the end-labeled deutrated-PS (dPS) film. These results suggest that the surface Tg is depressed due to an increase in free volume near surface region, being induced by the preferential surface localization of chain end groups.     

Sex Differences in Physical Activity in People After Stroke: A Cross-sectional Study

OBJECTIVE: Adequate physical activity after stroke is critical for cardiovascular health. Although sex is a potential factor associated with post-stroke physical activity, its mechanism remains unclear. This study aimed to examine sex differences in human physical activity following stroke. METHOD: A cross-sectional study with 62 participants (men: 42, women: 20) was conducted. Physical activity was measured for three consecutive days using a step activity monitor. The walking durations per day in light physical activity, moderate-to-vigorous physical activity, and total physical activity were calculated. Sex differences in walking duration were compared using Welch''s t-tests or Mann-Whitney U tests. RESULTS: Women had a significantly greater walking duration in light physical activity and in total than did the men. In contrast, no significant differences were found in moderate-to-vigorous physical activity. CONCLUSION: This study reported sex differences in the walking duration after stroke. Moreover, it found that women spent more time in low intensity physical activity than men. Our results will be useful for planning interventions to increase physical activity and decrease sedentary behavior after stroke.     

Melleumin A, a novel peptide lactone isolated from the cultured myxomycete Physarum melleum

Melleumin A (1), a novel peptide lactone, has been isolated from the laboratory-cultured plasmodium of myxomycete Physarum melleum, and its structure was elucidated by spectral data. Melleumin A (1) consisted of four residues (p-methoxybenzoic acid, l-threonine, glycine, and an unusual amino acid, a tyrosine-attached acetic acid).     

Cycloanthranilylproline-derived constituents from a myxomycete Fuligo candida

Cycloanthranilylproline (1) and its derivatives (2--4) were isolated from field-collected fruit-bodies of a myxomycete Fuligo candida and their structures were elucidated by spectral data. Compound 4, which was contained in the water-soluble fraction of the extract of this myxomycete, was unstable and quite susceptible to decarboxylation to yield compound 2, which was a major constituent of the EtOAc-soluble fraction of this extract.     

Two novel long-chain alkanoic acid esters of lupeol from alecrim-propolis

Two new long-chain alkanoic acid esters of lupeol were isolated together with known triterpenoids, alpha-amyrin, beta-amyrin, cycloartenol, lanosta-7,24-diene-3beta-ol and lupeol from Alecrim-propolis collected in Brazil. The structures were characterized by spectroscopic means.     

Discovery of a novel acyl-CoA: cholesterol acyltransferase inhibitor: the synthesis, biological evaluation, and reduced adrenal toxicity of (4-phenylcoumarin)acetanilide derivatives with a carboxylic acid moiety

As a part of our research for novel potent and orally available acyl-CoA: cholesterol acyltransferase (ACAT) inhibitors that can be used as anti-atherosclerotic agents, we recently reported the discovery of the (4-phenylcoumarine)acetanilide derivative 1. However, compound 1 showed adrenal toxicity in animal models. In order to search for safer ACAT inhibitors that do not have adrenal toxicity, we examined the inhibitory activity of ACAT in human macrophage and adrenal cells. The introduction of a carboxylic acid moiety on the pendant phenyl ring and the adjustment of the lipophilicity led to the discovery of (2E)-3-[7-chloro-3-[2-[[4-fluoro-2-(trifluoromethyl)phenyl]amino]-2-oxoethyl]-6-methyl-2-oxo-2H-chromen-4-yl]phenyl]acrylic acid (21e), which showed potent ACAT inhibitory activity in macrophages and a selectivity of around 30-fold over adrenal cells. In addition, compound 21e showed high adrenal safety in guinea pigs.