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1.
JACS Au ; 3(9): 2522-2535, 2023 Sep 25.
Article in English | MEDLINE | ID: mdl-37772180

ABSTRACT

Carbohydrate biosynthesis is fundamental to modern terrestrial biochemistry, but how this collection of metabolic pathways originated remains an open question. Prebiotic sugar synthesis has focused primarily on the formose reaction and Kiliani-Fischer homologation; however, how they can transition to extant biochemical pathways has not been studied. Herein, a nonenzymatic pathway for pentose production with similar chemical transformations as those of the pentose phosphate pathway is demonstrated. Starting from a C6 aldonate, namely, gluconate, nonselective chemical oxidation yields a mixture of 2-oxo-, 4-oxo-, 5-oxo-, and 6-oxo-uronate regioisomers. Regardless at which carbinol the oxidation takes place, carbonyl migration enables ß-decarboxylation to yield pentoses. In comparison, the pentose phosphate pathway selectively oxidizes 6-phosphogluconate to afford the 3-oxo-uronate derivative, which undergoes facile subsequent ß-decarboxylation and carbonyl migration to afford ribose 5-phosphate. The similarities between these two pathways and the potential implications for prebiotic chemistry and protometabolism are discussed.

2.
Orig Life Evol Biosph ; 49(3): 111-145, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31399826

ABSTRACT

In this review, we describe some of the central philosophical issues facing origins-of-life research and provide a targeted history of the developments that have led to the multidisciplinary field of origins-of-life studies. We outline these issues and developments to guide researchers and students from all fields. With respect to philosophy, we provide brief summaries of debates with respect to (1) definitions (or theories) of life, what life is and how research should be conducted in the absence of an accepted theory of life, (2) the distinctions between synthetic, historical, and universal projects in origins-of-life studies, issues with strategies for inferring the origins of life, such as (3) the nature of the first living entities (the "bottom up" approach) and (4) how to infer the nature of the last universal common ancestor (the "top down" approach), and (5) the status of origins of life as a science. Each of these debates influences the others. Although there are clusters of researchers that agree on some answers to these issues, each of these debates is still open. With respect to history, we outline several independent paths that have led to some of the approaches now prevalent in origins-of-life studies. These include one path from early views of life through the scientific revolutions brought about by Linnaeus (von Linn.), Wöhler, Miller, and others. In this approach, new theories, tools, and evidence guide new thoughts about the nature of life and its origin. We also describe another family of paths motivated by a" circularity" approach to life, which is guided by such thinkers as Maturana & Varela, Gánti, Rosen, and others. These views echo ideas developed by Kant and Aristotle, though they do so using modern science in ways that produce exciting avenues of investigation. By exploring the history of these ideas, we can see how many of the issues that currently interest us have been guided by the contexts in which the ideas were developed. The disciplinary backgrounds of each of these scholars has influenced the questions they sought to answer, the experiments they envisioned, and the kinds of data they collected. We conclude by encouraging scientists and scholars in the humanities and social sciences to explore ways in which they can interact to provide a deeper understanding of the conceptual assumptions, structure, and history of origins-of-life research. This may be useful to help frame future research agendas and bring awareness to the multifaceted issues facing this challenging scientific question.


Subject(s)
Biology/history , Chemistry/history , Historiography , Informatics/history , Origin of Life , Paleontology/history , Philosophy/history , History, 16th Century , History, 17th Century , History, 18th Century , History, 19th Century , History, 20th Century , History, 21st Century , Molecular Biology/history
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