Schematic representation of a metabolic branch point. The numbers represent chemical compounds, whereas the letters represent enzymes that catalyze the conversion indicated by the nearby arrow. In this scheme, enzyme c catalyzes the committed step in the biosynthesis of compound 6.
In enzymology, the committed step (also known as the firstcommitted step) is an effectively irreversible enzymatic reaction that occurs at a branch point during the biosynthesis of some molecules.[1][2]
As the name implies, after this step, the molecules are "committed" to the pathway and will ultimately end up in the pathway's final product. The first committed step should not be confused with the rate-limiting step, which is the step with the highest flux control coefficient. It is rare that the first committed step is in fact the rate-determining step.[3][4]
^Bhagavan, N. V. (2002). Medical biochemistry. San Diego: Harcourt/Academic Press. ISBN 0-12-095440-0.
^Berg, Jeremy M.; Tymoczko, John L.; Stryer, Lubert (2002). Biochemistry (5th ed.). W. H. Freeman and Company. p. 447. ISBN 0-7167-3051-0.
^Sauro, Herbert M. (February 2017). "Control and regulation of pathways via negative feedback". Journal of the Royal Society Interface. 14 (127): 20160848. doi:10.1098/rsif.2016.0848. PMC 5332569. PMID 28202588.
^Hofmeyr, Jan-Hendrik S.; Cornish-Bowden, Athel (August 1991). "Quantitative assessment of regulation in metabolic systems". European Journal of Biochemistry. 200 (1): 223–236. doi:10.1111/j.1432-1033.1991.tb21071.x. PMID 1879427.
In enzymology, the committedstep (also known as the first committedstep) is an effectively irreversible enzymatic reaction that occurs at a branch point...
by the enzyme pantothenate kinase (PanK; CoaA; CoaX). This is the committedstep in CoA biosynthesis and requires ATP. A cysteine is added to 4′-phosphopantothenate...
Dephosphorylation of xanthosine-5'-monophosphate into xanthosine is the committedstep for the xanthosines entering the beginning of the most common pathway...
by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose...
not the committedstep to purine synthesis because PRPP is also used in pyrimidine synthesis and salvage pathways. The first committedstep is the reaction...
olpyruvyltransferase, also known as MurA. This enzyme catalyzes the committedstep in peptidoglycan biosynthesis, namely the ligation of phosphoenolpyruvate...
supports hepatic ketogenesis. The specific step catalyzed by MCAD involves the dehydrogenation of acyl-CoA. This step converts medium-chain acyl-CoA to trans-2-enoyl-CoA...
glycine (N&C), aspartate (N), folic acid (C1), or CO2. This is the committedstep in purine synthesis. The reaction occurs with the inversion of configuration...
4′-phosphopantothenate by the enzyme pantothenate kinase. This is the committedstep in CoA biosynthesis and requires ATP. A cysteine is added to 4′-phosphopantothenate...
first enzymes of the pathway (usually the first irreversible step, called committedstep), thus regulating the amount of end product made by the pathways...
carboxylated by acetyl-CoA carboxylase into malonyl-CoA, the first committedstep in the synthesis of fatty acids. Malonyl-CoA is then involved in a repeating...
tail-to-tail configuration to give the 40-carbon phytoene, the first committedstep in carotenoid biosynthesis. Through several desaturation steps, phytoene...
product of the urea cycle) to form putrescine. This reaction is the committedstep in polyamine synthesis. In humans, this protein has 461 amino acids...
and protozoa, as well as the α-proteobacteria group of bacteria, the committedstep for porphyrin biosynthesis is the formation of δ-aminolevulinic acid...
carboxylated by acetyl-CoA carboxylase into malonyl CoA, the first committedstep in the synthesis of fatty acids, or it can be combined with acetoacetyl-CoA...
carboxylated by acetyl CoA carboxylase into malonyl CoA, the first committedstep in the synthesis of fatty acids. Acetyl-CoA is formed into malonyl-CoA...
The reaction catalyzed by DGAT is considered the terminal and only committedstep in the acyl-CoA-dependent triglyceride synthesis, universally important...
second ATP to give carbamoyl phosphate plus ADP. It represents the first committedstep in pyrimidine and arginine biosynthesis in prokaryotes and eukaryotes...
Module Columbia. When Armstrong first stepped onto the lunar surface, he famously said: "That's one small step for [a] man, one giant leap for mankind...
a phosphocholine from phosphatidylcholine to a ceramide. The first committedstep of sphingomyelin synthesis involves the condensation of L-serine and...
G, Breitel D, Grossman N, et al. (2016). "Elucidation of the first committedstep in betalain biosynthesis enables the heterologous engineering of betalain...
ring opening of guanosine triphosphate (GTP). This reaction is the committedstep in the biosynthesis of multiple coenzymes (such as riboflavin and folate)...
AK-III catalyzes the phosphorylation of aspartic acid that is the committedstep in this biosynthetic pathway. Aspartate kinase becomes downregulated...
carboxylated by acetyl CoA carboxylase into malonyl CoA, the first committedstep in the synthesis of fatty acids. The main fuel stored in the bodies...
The following is an episode list for the American television sitcom Step by Step. The series originally ran for six seasons on ABC from September 20, 1991...
Global Information