Common to all FASs, PKSs and NRPSs is a remarkable component, the acyl or peptidyl carrier protein (A/PCP). These take the form of small individual proteins in type II systems or discrete folded ...domains in the multi-domain type I systems and are characterized by a fold consisting of three major α-helices and between 60-100 amino acids. This protein is central to these biosynthetic systems and it must bind and transport a wide variety of functionalized ligands as well as mediate numerous protein-protein interactions, all of which contribute to efficient enzyme turnover. This review covers the structural and biochemical characterization of carrier proteins, as well as assessing their interactions with different ligands, and other synthase components. Finally, their role as an emerging tool in biotechnology is discussed.
Three-coordinate bipyridyl complexes of gold, (κ2-bipy)Au(η2-C2H4)NTf2, are readily accessed by direct reaction of 2,2′-bipyridine (bipy), or its derivatives, with the homoleptic gold ethylene ...complex Au(C2H4)3NTf2. The cheap and readily available bipyridyl ligands facilitate oxidative addition of aryl iodides to the Au(I) center to give (κ2-bipy)Au(Ar)INTf2, which undergo first aryl-zinc transmetalation and second C–C reductive elimination to produce biaryl products. The products of each distinct step have been characterized. Computational techniques are used to probe the mechanism of the oxidative addition step, offering insight into both the origin of the reversibility of this process and the observation that electron-rich aryl iodides add faster than electron-poor substrates. Thus, for the first time, all steps that are characteristic of a conventional intermolecular Pd(0)-catalyzed biaryl synthesis are demonstrated from a common monometallic Au complex and in the absence of directing groups.
Compartmentalization of the minimal complex of actinorhodin polyketide synthase in coacervate liquid droplets produces enhanced yields of shunt polyketides under conditions of low and high ionic ...strength.
Abstract Most mesenchymal neoplasms of the gastrointestinal tract are currently classified as gastrointestinal stromal tumors (GIST). Gastrointestinal stromal tumors are diagnosed by immunopositivity ...for CD117, CD34, and DOG1.1, with or without molecular analyses. According to the World Health Organization classification, the diagnosis of primary leiomyosarcomas of the gastrointestinal tract is so rare that there are no significant data on demographic, clinical, or gross features of this tumor. A comprehensive literature search was performed to identify gastrointestinal leiomyosarcomas. Searches were limited to the past 12 years because definitive tools to differentiate leiomyosarcomas from GIST were introduced in the late 1990s. Cases were included only if convincing data were presented. Six cases of esophageal leiomyosarcoma and 5 cases of gastric leiomyosarcoma were confirmed. Furthermore, 26 cases of leiomyosarcoma of the small bowel, 11 cases of the colon, and 8 cases arising in the rectum were identified. Finally, 28 cases of infantile and adolescent leiomyosarcoma were reviewed. Although survival analysis is precluded by small case numbers and limited survival data availability, the trend identifies that increased size and mitotic activity portends to a worse prognosis in small bowel leiomyosarcomas. Colonic leiomyosarcomas appear to be aggressive tumors, regardless of tumor size and mitotic activity. Rectal leiomyosarcomas present as smaller tumors with favorable prognosis. Leiomyosarcomas in post-GIST era are rare tumors of the gastrointestinal tract with distinctive clinicopathologic characteristics. Owing to different treatment options, it is necessary to accurately differentiate these from GIST, using a combination of histologic appearance, presence of smooth muscle antigens, and absence of specific GIST immunomarkers.
Much has been written about the great personalist philosophers of the 20th century - including Jacques Maritain and Emmanuel Mournier, Martin Buber and Emmanuel Levinas, Dietrich von Hildebrand and ...Edith Stein, Max Scheler and Karol Wojtyla (later Pope John Paul II) - but few books cover the personalist movement as a whole.An Introduction to Personalismfills that gap.Juan Manuel Burgos shows the reader how personalist philosophy was born in response to the tragedies of two World Wars, the Great Depression, and the totalitarian regimes of the 1930s. Through a revitalization of the concept of the person, an array of thinkers developed a philosophy both rooted in the best of the intellectual tradition and capable of dialoguing with contemporary concerns.Burgos then delves into the potent ideas of more than twenty thinkers who have contributed to the growth of personalism, including Romano Guardini, Gabriel Marcel, Xavier Zubiri, and Michael Polanyi. Burgos's encyclopedic knowledge of the movement allows for a concise and well-rounded perspective on each of the personalists studied.An Introduction to Personalismconcludes with a synthesis of personalist thought, bringing together the brightest insights of each personalist philosopher into an organic whole. Burgos argues that personalism is not an eclectic hodge-podge, but a full-fledged school of philosophy, and gives a dynamic and rigorous exposition of the key features of the personalist position.Our times are marked by numerous and often contradictory ideas about the human person.An Introduction to Personalismpresents an engaging anthropological vision capable of taking the lead in the debate about the meaning of human existence and of winning hearts and minds for the cause of the dignity of every person in the 21st century and beyond.
We present a new term-structure model for commodity futures prices based on Trolle and Schwartz (2009), which we extend by incorporating multiple jump processes. Our work explores the valuation of ...plain vanilla options on futures prices when the spot price follows a log-normal process, the forward cost of carry curve and the volatility are stochastic variables, and the spot price and the forward cost of carry allow for time-dampening jumps. We obtain an analytical representation of the characteristic function of the futures prices and, hence, also for plain vanilla option prices using the fast Fourier transform methodology. We price options on WTI crude oil futures contracts using our model and extant models. We obtain higher accuracy than earlier models and save significantly in computing time.
•A novel model of commodity prices with multiple types of jumps.•Closed-form solutions for plain vanilla options.•Faster pricing and parameter calibration.•Empirical analysis of WTI crude oil demonstrates improvement in model performance.
Increasing numbers of disillusioned and thoughtful persons find they can no longer maintain a simplistic concept of theism, be it Christian, Jewish, or Islamic. But the shock that comes with loss of ...faith, and the challenges of learning to restructure ones life if one has been a believer, can seem overwhelming. "Aftermath" gives a sound foundation for building a meaningful life without god.
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