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Crystal structure of ribose 5-phosphate isomerase and ribose 5-phosphate complex in E. coli. R5P consists of a five-carbon sugar, ribose, and a phosphate group at the five-position carbon. It can exist in open chain form or in furanose form. The furanose form is most commonly referred to as ribose 5-phosphoric acid. [1]
Ribose-5-phosphate isomerase (Rpi) encoded by the RPIA gene is an enzyme (EC 5.3.1.6) that catalyzes the conversion between ribose-5-phosphate (R5P) and ribulose-5-phosphate (Ru5P). It is a member of a larger class of isomerases which catalyze the interconversion of chemical isomers (in this case structural isomers of pentose ).
These three components are connected so that the nitrogenous base is attached to the first carbon of ribose (1’ carbon), and the phosphate group is attached to the 5’ carbon of ribose. While all nucleotides have this structure, the phosphate group makes a second connection to the ribose ring at the 3’ carbon in cyclic nucleotides. Because ...
The general structure of a ribonucleotide consists of a phosphate group, a ribose sugar group, and a nucleobase, in which the nucleobase can either be adenine, guanine, cytosine, or uracil. Without the phosphate group, the composition of the nucleobase and sugar is known as a nucleoside.
L-Ribose Fischer Projection. Ribose is a simple sugar and carbohydrate with molecular formula C 5 H 10 O 5 and the linear-form composition H−(C=O)−(CHOH) 4 −H. The naturally occurring form, d-ribose, is a component of the ribonucleotides from which RNA is built, and so this compound is necessary for coding, decoding, regulation and expression of genes.
A key regulatory step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate by ribose-phosphate diphosphokinase, which is activated by inorganic phosphate and inactivated by purine ribonucleotides. It is not the committed step to purine synthesis because PRPP is also used in pyrimidine synthesis and salvage pathways.
Thus the structure of the linear form is H–(CHOH) x –C(=O)–(CHOH) 4-x –H, where x is 0, 1, or 2. The term "pentose" sometimes is assumed to include deoxypentoses, such as deoxyribose: compounds with general formula C 5 H 10 O 5-y that can be described as derived from pentoses by replacement of one or more hydroxyl groups with hydrogen ...
The 3 substrates of this enzyme are ATP, ribose 5-phosphate, and NH 3, whereas its 3 products are ADP, phosphate, and 5-phosphoribosylamine. This enzyme belongs to the family of ligases, specifically those forming generic carbon-nitrogen bonds. The systematic name of this enzyme class is ribose-5-phosphate:ammonia ligase (ADP-forming).