A new class of biheterocyclic thioglycosides from pyridine-2-(1H)-thiones

A reported method for preparation of a new class of biheterocyclic thioglycosides via reaction of pyridinethiones with 2,3,4,6-tetra-O-acetyl-alpha-D-gluco- and galactopyranosyl bromides has been studied.     

Use of thiocyanic acid to form 2-thiohydantoins at the carboxyl terminus of proteins.

The chemistry of the formation of 2-thiohydantoins on the carboxyl terminal of peptides or proteins was investigated. It was found that thiocyanic acid was much more reactive for the formation of 2-thiohydantoins than were the thiocyanate salts. The physical reasons for this observation are explained. The kinetics of the reaction of a number of proteins, and some of their fragments, with thiocyanic acid were also determined. Simple and safe procedures for the preparation of anhydrous thiocyanic acid solutions were devised. The prospective application of these procedures to sequencing from the carboxyl terminal of a polypeptide is discussed.     

A new route to the evolution of cooperation

The Prisoner's Dilemma (PD) constitutes a widely used metaphor to investigate problems related to the evolution of cooperation. Whenever evolution takes place in well-mixed populations engaged in single rounds of the PD, cooperators cannot resist invasion by defectors, a feature, which is somewhat alleviated whenever populations are spatially distributed. In both cases the populations are characterized by a homogeneous pattern of connectivity, in which every individual is equivalent, sharing the same number of neighbours. Recently, compelling evidence has been accumulated on the strong heterogeneous nature of the network of contacts between individuals in populations. Here we describe the networks of contacts in terms of graphs and show that heterogeneity provides a new mechanism for cooperation to survive. Specifically, we show that cooperators are capable of exploring the heterogeneity of the population structure to become evolutionary competitive. As a result, cooperation becomes the dominating trait in scale-free networks of contacts in which the few highly connected individuals are directly inter-connected, in this way contributing to self-sustain cooperation.     

A new synthetic route to monophosphaferrocenes

Phosphacyclopentadienyl anions (A) derived from 1 phenylphospholes cleave the η⁶-bonded arene from η⁶-arene-η⁵-cyclopentadienyliron(II) cations (B)via nucleophilic attack at iron to yield η⁵-cyclopentadienyl- η⁵-phosphacyclopentadienyliron(II) sandwich compounds (C).

The reaction provides a versatile synthetic route to phosphaferrocenes with one general reaction giving a pathway to phosphaferrocenes with greatly varying degrees of ring substitution.     

A new route of prostaglandin F-2α transfer from the uterus into the ovary in swine

On day 14 of the oestrous cycle in swine, laparotomy under general anaesthesia was performed and both ovaries with their ovarian pedicles and with part of the uterine horns were isolated using ligatures and excised as two independent units which were called A and B. They were placed in separate aluminium paper boxes on a heated surface (40°C). Preparation A was supplied with autologous arterial blood through the uterine artery and through the ovarian artery. The mesosalpinx of this preparation covered the ovary of preparation B from which the mesosalpinx was excised. Preparation B was also supplied with autologous blood through the ovarian artery. Tritiated prostaglandin F-2α (³H-PGF-2α) was injected into the musculature of the uterine horn of preparation A and then both preparations were perfused with blood of the same animal for 30 min. ³H-PGF-2α was found in the ovarian venous blood, interstitial fluid, and ovarian and pedicle tissue of preparation B. The data indicate an extravascular penetration of ³H-PGF-2α into the ovary through the mesosalpinx.     

The identification of 1,3-oxazolidine-2-thiones and 1,3-thiazolidine-2-thiones from the reaction of glucose with benzyl isothiocyanate

The structure of interaction products resulting from the reaction of unmodified glucose with benzyl isothiocyanate is reported. Prior to their identification, the main products of this reaction were isolated using solid-phase extraction (SPE) as well as preparative HPLC. They were then identified by NMR and MS as 3-benzyl-4-hydroxy-5-(D-arabino-1,2,3,4-tetrahydroxybutyl)-1,3-oxazolidine-2-thione, 3-benzyl-4-hydroxy-4-hydroxymethyl-5-(D-erythro-1,2,3-trihydroxypropyl)-1,3-oxazolidine-2-thione, N-benzyl-(D-gluco-4,5-dihydroxy-6-hydroxymethyl-tetrahydropyrano)[2,3-b]oxazolidine-2-thione and 3-benzyl-4-(N-benzyl amino)-5-(D-arabino-1,2,3,4-tetrahydroxybutyl)-1,3-thiazolidine-2-thione. The identity of the last compound was secured by X-ray crystal structure data.     

A new route to polyamino acids containing histidine

A new route for the synthesis of polyamino acids containing histidine is described and illustrated in the preparation of poly l-histidine. This method involves the use of the 2,4-dinitrophenyl group for the protection of the imidazole imino-nitrogen during polymerization. The N-carboxy anhydride of N^Im-DNP-l-histidine was polymerized to yield poly (DNP-l-histidine) with an average molecular weight of 29,400. After polymerization, the protecting groups were removed under very mild reaction conditions by thiolysis with mercaptans in N,N′-dimethylformamide (22 °). The mildness of the conditions for deblockage allows the preparation of histidine-containing polyamino acids and polypeptidyl proteins which could not be prepared by the previously available methods.     

A new synthetic route to 2- and 4-methoxyestradiols by nucleophilic substitution

A new snythetic route to 2- and 4-methoxyestradiols is described. Benzo-15-crown-5 with CuI catalyzes the specific nucleophilic substitution at the carbon atom carrying a non-activated halogen on ring A of the estradiol.     

Changes of structure and energy on the route from dioxetane to carbonyl products. A quantum chemical study

Energy diagrams, changes of geometry and bond orders were calculated semi-empirically for the thermolysis of 1,2-dioxetane. Stretching of the O–O bond, then of the C–C bond and distortion of the whole quadrangular structure make major, but different, contributions to the reaction coordinate on the path to formaldehyde. The activation barrier represents a vast region where the gaps between the ground and excited states are small, and this favours horizontal radiationless transitions leading to the excitation of a product. The results show that semi-empirical calculations may help to provide better insight into the nature and mechanism of the chemiluminescence excitation. © 1998 John Wiley & Sons, Ltd.     

A microbial transporter of the dietary antioxidant ergothioneine

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A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.     

Ca2+ signalling: a new route to NAADP

The LKB1 serine/threonine kinase is a tumour suppressor responsible for the inherited familial cancer disorder Peutz-Jeghers syndrome and is inactivated in a large percentage of human lung cancers. LKB1 acts a master kinase, directly phosphorylating and activating a family of 14 AMPK (AMP-activated protein kinase)-related kinases which control cell metabolism, cell growth and cell polarity. In this issue of the Biochemical Journal, Hardie and colleagues discover an alternative splice form of LKB1 that alters the C-terminus of the protein containing a few known sites of post-translational regulation. Although widely expressed, the short isoform (LKB1(s)) is the sole splice isoform expressed in testes, and its expression peaks at the time of spermatid maturation. Male mice lacking the LKB1(s) isoform have dramatic defects in spermatozoa, resulting in sterility.     

A new synthetic route to 2-hydroxyl steroidal estrogens via acetylation and dakin oxidation

This paper describes a new two-step synthetic route to 2-hydroxy estrogens from either estrone or estradiol, via 2-acetylation followed by Dakin oxidation. This approach is characterized by its simplicity and excellence of yield.