Protein myristoylation was first discovered in the catalytic subunit of adenosine 3', 5'-cyclic monophosphate-dependent protein kinase. Subsequently, various cellular and viral myristoylated proteins were detected. In each case, the myristoyl moiety was found in an amide linkage with the amino terminal glycine residue of the modified proteins. The biological functions of protein myristoylation of various cellular protein, oncogene product, and viral structural proteins have been studied by many biochemists. Two of the most throughly studies myristoylated proteins are the transforming protein of Rous sarcoma virus, pp60v-src, and the proto-oncogene product, pp60v-src. Deletion, modification of the first 14 NH2-terminal amino acid of pp60v-src, or chemical antimyristoylation of the protein with N-myristoyl glycinal diethylacetal dose not affect intrinsic tyrosine src-kinase activity, but prevents myristoylation and membrane association, and abolishes the transforming activity of the protein. Protein myristoylations of some viral structural proteins were also studied by many investigators, and X-ray crystallographic studies of poliovirus suggest that myristate moiety may play a central role in capside assembly. Recently, human immunodeficiency virus, HIV-I, prossesses a myristoylated p17gag protein, which is proteolytically derived from the NH2-terminus of a gag precursor protein, and its myristate moiety may be important for virus assembly. In this review, we detailed recent studies of the protein myristoylation in cellular regulation and virus proliferation.
The association of riboflavin tetrabutyrate (RTB) in solution was studied by infrared, 1H-nuclear magnetic resonance and emission spectra. In CCl4, hydrogen bonds and stacking between isoalloxazine rings of RTB were observed, and in CHCl3 the solvation to RTB mainly took place. Both the solvation and stacking of RTB were observed in (CD3)2CO, CD3OD, and CH3OH over a wide range of the concentration of RTB. The maxima in emission spectra of RTB solution were respectively attributed to RTB monomer and associated molecules by stacking.
4'-Carbamoyl-1, 4'-bipiperidine 1 was dehydrogenated on Pd-C to give 2-oxo-2, 3, 5, 6, 7, 8-hexahydroimidazo [1, 2-α] pyridine-3-spiro-4'-piperidine 2, which was reduced to 2-oxo-1, 2, 3, 5, 6, 7, 8, 8a-octahydroimidazo [1, 2-α] pyridine-3-spiro-4'-piperidine 3 with NaBH4. The iminodibenzyl and similar derivatives of 2 and 3 were synthesized and evaluated by using antiapomorphine test in mice. The derivatives of 3 had more potent antagonistic activity than those of 2 and the order of potency of 3 was : chloriminodibenzyl > chlordibenzocycloheptene > iminodibenzyl > iminostilbene > fluorene. Further chemical modification of the most active chloriminodibenzyl derivative 8, such as the substitution of Cl atom to Br atom, N-methylation on amine moiety, the replacement of imidazopyridine ring to imidazopyrrole ring, did not give any positive effect. Therefore, 8 may have potential usefulness as an antipsychotic drug.
The hydroxyl radicals (HO·) spin adduct of 5, 5'-dimethyl-1-pyrroline-N-oxide (DMPO) was obtained in the hypoxanthine-xanthine oxidase (HX-X.O.) system in the presence of isolated islet cells by using electron spin resonance spectroscopy. There was a significant increase in the concentration of DMPO-OH spin adduct dependent on the increase in a number of islet cells. In the absence of islet cell, the DMPO-OOH spin adduct formed by superoxide together with a small amount of DMPO-OH spin adduct was detected in HX-X.O. system. These results suggest that HO· is greatly produced in the HX-X.O. system in the presence of islet cells. The generation of HO· was partially inhibited by the addition of superoxide dismutase or catalase and completely by the combined use of both enzymes. Iron-chelator, diethylenetriaminepentaacetic acid and iron-binding protein, apotransferrin also inhibited the generation of HO·, suggesting a possible participation of a trace iron in the islet cells. The inhibition of insulin release from islet cell, as well as the amount of DMPO-OH spin adduct, was dependent on the concentration of X. O. These results indicate that the HO· is produced by the site-specific action with islet cells in HX-X.O. system, suggesting a possible involvement of HO· in the oxygen damages of islet cells.
Inclusion complexations of clomipramine HCl (CIP), a tricyclic antidepressant, with β-cyclodextrin (β-CyD) and heptakis (2, 6-di-O-methyl) -β-CyD (DM-β-CyD) were studied by ultraviolet, fluorescence, circular dichroism and 13C-nuclear magnetic resonance spectroscopies. Both β-CyDs decelerated the photodegradation of CIP under aerobic and anaerobic conditions, where the inhibitory effect of DM-β-CyD was larger than that of β-CyD. The photodegradation products of CIP in the absence and presence of DM-β-CyD were analyzed by liquid chromatography/mass spectroscopy. The results indicate that β-CyDs suppress the formation of 3-hydroxyimipramine, while they accelerate the formation of imipramine. The alternation in photochemical reaction of CIP may result from the inclusion of chlorobenzene moiety of CIP molecule within the hydrophobic cavity of β-CyDs.
The protective potency against skin injury on mice induced by X-irradiation was studied by use of 72 extracts of crude drugs. The protective potency was determined according to the degrees on skin injury after irradiation of 1100R, 30kVp soft X-ray. As a result of these study, 16 kinds of crude drugs such as Rosae Fructus, Aloe arborescens (Herba), Citri Leiocarpae Exocarpium, Schizonepetae Spica, Evodiae Fructus, Bupleuri Radix, Corni Fructus, Perillae Herba, Anemarrhenae Rhizoma, Menthae Herba, Trapae Fructus, Angelicae Dahuricae Radix, Sinomeni Caulis et Rhizoma, Ephedrae Herba, Acer nikoense (Cortex), Forsythiae Fructus, revealed protective potencies on skin injury.
Comparing with other pyridonecarboxylic acids (PCAs), the neurotoxicity of (±) -7- (3-amino-1-pyrrolidinyl) -6-fluoro-1- (2, 4-difluorophenyl) -1, 4-dihydro-4-oxo-1, 8-naphthyridine-3-carboxylic acid p-toluenesulfonate hydrate (T-3262), which is a new PCA, was investigated in mice in a combination with fenbufen (FBF). T-3262, ofloxacin (OFLX) and nalidixic acid (NA) did not produce convulsion, but enoxacin (ENX) and norfloxacin (NFLX) produced it after an oral administration with FBF. The intracerebral injection of drugs alone to mice revealed that both FBF and 4-biphenylacetic acid (BPAA), which is principally responsible for FBF's antiinflammatory action, scarcely had convulsant activity. While all the PCAs had convulsant activity and the order of potency was as follows ; NFLX > ENX > OFLX > penicillin G potassium > the free base of T-3262 (T-3262 base) ≨ NA. When orally pretreated with BPAA, the convulsive threshold was scarcely lowered for T-3262 base and OFLX, but for ENX and NFLX it was lowered to about 1/300 and 1/100 of the respective activity. As the result, convulsant activities of ENX and NFLX were greatly potentiated, and their potencies became almost equal. The adverse drug interactions between T-3262 and FBF were scarcely observed in mice.
In order to identify the constituents of ethanol-extractable amino acids (free amino acids) from Pinus densiflora SIEB. et ZUCC. and Pinus thunbergii PARL. leaves, analytical studies were performed by the use of high performance liquid chromatography. According to the results obtained, 29 amino acids in Pinus densiflora (the tree aged 3), 27 amino acids in Pinus thunbergii (the tree aged 3) and 25 amino acids in both pine (the tree aged 25) were confirmed. The total amounts of free amino acids in Pinus densiflora were found to be more rich than in Pinus thunbergii. The peaks of many free amino acids in Pinus densiflora (the tree aged 3) were found in February, but in Pinus thunbergii (the tree aged 3) the peaks of free amino acids were observed in May and from February to April. The mode of occurrence of asparagine at germination of buds explains clearly the distinction between Pinus densiflora and Pinus thunbergii.
A simple and sensitive high performance liquid chromatography (HPLC) with a fluorescence detection was developed for the determination of p-benzoquinones. The method was based on the reduction of p-benzoquinones to the corresponding fluorescent hydroquinones with sodium borohydride. The most sensitive and quantitative procedure was achieved when p-benzoquinones were reduced in methanol for 5 min and the fluorescence was monitored with the second-order emission. The detection limit of p-benzoquinone was 10 pg for an injection volume of 10 μl (S/N=2) and the coefficient of variation was found to be 2.60% (n=8) at 400 pg of p-benzoquinone.