Rosenberg, Harry2013-01-222013-01-22b16496358http://hdl.handle.net/1885/9610Nearly half a century ago the element phosphorus was introduced into biochemistry with the observation of Harden and Young (1905) that inorganic phosphate added to fermenting yeast could not, after a time, be precipitated with either magnesia mixture or silver nitrate. The subsequent work of Harden and Young (1906, 1908) produced evidence that the phosphate was esterified and largely appeared in a form of hexose phosphate. At that time the compound was considered to be merely a by-product of fermentation and its general importance was not realised until eight years later when Embden, Griesbach and Schmitz (1914) found hexose di-phosphate in skeletal muscle. The five decade that passed witnessed the advent of phosphorus to a position of major importance in the metabolic reactions of living matter and it has been stated that “among the mineral elements essential to life none plays a more central role than phosphorus.” (Glass, 1951). The function of phosphate in the economy of vertebrates can be divided into two main parts: The first, and quantitatively the lesser part of the body phosphorus that has attracted the attention of the biochemist occupied with the metabolic reactions of the cell. Less than 20% of the body phosphorus can be found in the so-called acid-soluble fraction which contains, apart from orthophosphate, a multitude of soluble organophosphates. The distribution in the body of these compounds varies. About half of the total acid soluble fraction is found in the muscles; the remainder is distributed to a varying extent in other tissues and its presence is probably essential in every living cell. After the discovery by Harden and Young in 1906 of hexose phosphate, knowledge of the role of phosphorus was not appreciably increased until about 1926. The decade that followed 1926 brought into this field a number of new contributions of which the most outstanding were: The fact that hexose phosphate was formed not as the result of a side reaction but was the first of a series of phosphorylated intermediated which arose as a result of the stepwise degradation of glucose. This series of reactions, all of which were reversible, became known as the hexose, or glycolytic cycle. It was also observed that metabolic reactions depended upon the presence of complex compounds, named nucleotides, all containing phosphate groups and which were required in catalytic amounts. To this group belonged the adenylic system (phosphorylation), phosphopyridine nucleotides ( oxidation and reduction) and diphosphothiamine nucleotide (decarboxylation). As the result of study of phosphorylation reactions it was found that in many of these the transfer of phosphate was direct from compound to compound without the intermediate liberation of inorganic phosphate. One of the most interesting aspects of the work involving phosphorylated intermediates was the discovery that some of these compounds contained phosphate bonds of a far higher energy content than those of ordinary phosphate esters. This last observation was of prime importance for the understanding of the fundamental reactions involving liberation of energy in various forms by living tissues. In this group of compounds belong the adenine nucleotides and the phosphagen of vertebrate and invertebrate muscle phosphor-creatine and phosphoarginine.en-AUphosphocreatinecreatine kinase195510.25911/5d78da244f195