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American biochemist (1912–1998)

Sidney Walter Fox (24 March 1912 – 10 August 1998) was a Los Angeles born biochemist responsible for discoveries on the origins of biological systems. Fox explored the synthesis of amino acids from inorganic molecules, the synthesis of proteinous amino acids and amino acid polymers called "proteinoids" from inorganic molecules and thermal energy, and created what he thought was the world's first protocell out of proteinoids and water. He called these globules "microspheres". Fox believed in the process of abiogenesis where life spontaneously organized itself from the colloquially known "primordial soup;" poolings of various simple organic molecules that existed during the time before life on Earth. He also suggested that his experiments possessed conditions that were similar to those of primordial Earth. In his experiments, Fox demonstrated that it is possible to create protein like structures from inorganic molecules and thermal energy. Fox went on to create microspheres that he said closely resembled bacterial cells and concluded that they could be similar to the earliest forms of life or protocells.

Sidney Fox was the son of Jacob Fox, a wig maker, and Louise Berman, a Ukrainian immigrant. Fox married Raia Joffe in Chemistry. He went on to earn a Ph. D. from California Institute of Technology and did his postdoctoral work at the Linus Pauling Laboratory where he grew close with Linus Pauling. In 1964, Fox and Kaoru Harada performed an experiment yielding similar results. In this experiment, methane flowed through a concentrated solution of ammonium hydroxide and then into a hot tube containing silica sand at about 1000 °C. Fox indicated that silica gel, volcanic lava, and alumina could be used in place of silica sand. The gas was then absorbed in cold, aqueous ammonia. The result was twelve protein like amino acids: aspartic acid, glutamic acid, glycine, alanine, valine, leucine, isoleucine, serine, threonine, proline, tyrosine, and phenylalanine. The experiment began with L glutamic acid heated in an oil bath. DL aspartic acid and an amino acid mixture were added to the L glutamic acid and heated for three hours in the oil bath under a layer of CO2. The solution was cooled and the glass container it was in was rubbed with 20 mL of water and sat overnight. The result was a grainy precipitate. The next day, 10 mL of water and 10 mL of ethanol were added to the precipitate and filtered. The solid left over from filtering was put in cellophane dialysis tubing and left in a water bath for four days. When the inside of the tubes were observed and chromatograms were taken, it showed the presence of polypeptide chains. Fox called these protein like structures "proteinoids." The polypeptide chains were composed of glutamic acid, aspartic acid, and amino acids and the percentages of each suggested that the arrangement of the constituents were non random. The experiment was meant to resemble the drying out of amino acids in similar conditions to those of primordial Earth. The experiment did not prove that proteins were formed on primordial earth using primarily heat, but Fox and Kaoru Harada believed it suggested that if proteinoids could be synthesized using just heat and the amino acids formed from the Miller–Urey experiment, then more research could lead to an answer to how anabolic reactions, enzymatic proteins, and nucleic acids were first formed and in turn, how the earliest forms of life originated. Microspheres have multiple properties that are similar to those of cells. The microspheres produced were mostly uniformly spherical and Fox believed that the shape and uniformity mimics that of coccoid bacteria. He also believed that the uniformity meant that there was a sophisticated system that kept the microspheres at equilibrium. The microspheres were able to asexually divide via binary fission, could form junctions with other microspheres, and developed a double membrane corresponding to that of a cell.

Sidney Fox wrote or co wrote about 380 published works, nine of which are books. Fox, Sidney W. (1965). The origins of prebiological systems and of their molecular matrices. New York: Acad. Pr. Fox, Sidney W., Klaus Dose ; with a foreword by A. Oparin (1977). Molecular evolution and the origin of life (Rev. ed. ed.). New York: M. Dekker. Ho, edited by Mae Wan; Fox, Sidney W. (1988). Evolutionary processes and metaphors. Chichester: Wiley. pp. 333. Fox, Sidney W. (1988). The emergence of life: Darwinian evolution from the inside. Basic Books. Fox, Sidney W. (1957). Introduction to protein chemistry. New York: Wiley. Fox, Sidney W.; Duane L Rohlfing, Aleksandr Ivanovich Oparin (1972). Molecular evolution: prebiological and biological. New York: Plenum Press. Fox, Sidney W. (1984). Individuality and determinism: chemical and biological bases. New York: Plenum Press.