Carbamoyltransferase

Gouaux, J.E., Lipscomb, W.N. Crystal structures of phosphonoacetamide ligated T and phosphono-acetamide and malonate ligated R states of aspartate carbamoyltransferase at 2.8 A resolution and neutral pH. Biochemistry 29 389-402, 1990. 

EC2 Transferases methyltransferase, aspartate carbamoyltransferase, etc.) EC2.3 Acvltransferases (amino-acid N-acetyltransferase, ATP citrate synthase, etc.) luciferasa ... 

Aletor, V.A. and B.L. Fetuga. 1988. The interactive effects of lima bean (Phaseolus lunatus) trypsin inhibitor, hemagglutinin and cyanide on some hepatic dehydrogenases, ornithine carbamoyltransferase and intestinal disaccharidases in weanling rats. Veterin. Human Toxicol. 30 540-544. 

Doubly wound parallel fi sheet Aspartate carbamoyltransferase, (Monaco et ah, 1978)... 

Catalytic domain 1 doubly wound parallel fi sheet Catalytic domain 2 classic doubly wound fi sheet (Fig. 76) Aspartate transaminase see Aspartate aminotransferase Aspartate transcarbamylase (Monaco et ah, 1978), see Aspartate carbamoyltransferase... 

Figure 3.13 (a) Feedback control of a hypothetical pathway. (b) Feedback control of threonine deaminase in the isoleucine synthetic pathway and of aspartate carbamoyltransferase in the cytidine triphosphate synthetic pathway in the bacterium E. coli. 

A different, simpler , pathway is involved in the synthesis of pyrimidine nucleotides. A pyrimidine base (orotate), is synthesised first. Then the ribose is added from 5-phosphoribosyl 1-pyrophosphate. The two precursors for the formation of orotate are carbamoylphosphate and aspartate, which form carbamoyl aspartate, catalysed by aspartate carbamoyltransferase. 

The regulation of bacterial aspartate carbamoyltransferase by ATP and CTP has been particularly well studied, and is discussed on p. 116. In animals, in contrast to prokaryotes, it is not ACTase but carbamoyl-phosphate synthase that is the key enzyme in pyrimidine synthesis. It is activated by ATP and PRPP and inhibited by UTP. 

Like aspartate carbamoyltransferase (see p. 116), Hb can exist in two different states (conformations), known as the T form and... 

At least two gene products, the putative carbamoylsynthase TobL and the carbamoyltransferase TobZ are needed for the carbamoylation found in the NEBs. The respective enzymes are unique among the AGA gene clusters analyzed so far. Because NEBs are mainly found as a complex of NEB-4 and NEB-5, the TobZ protein must recognize both KAN-B and TOB as substrates. Therefore the carbamoylation must be the final step in the NEB biosynthesis, as illustrated in Figure 2.16b. 

This enzyme [EC 3.5.3.12], also known as agmatine imi-nohydrolase, catalyzes the hydrolysis of agmatine to produce A/ -carbamoylputrescine and ammonia. The plant enzyme also catalyzes the reactions of EC 2.1.3.3 (ornithine carbamoyltransferase), EC 2.1.3.6 (putrescine car-bamoyltransferase) and EC 2.122 (carbamate kinase), thereby functioning as a putrescine synthase, converting agmatine and ornithine into putrescine and citrulline, respectively. 

This enzyme [EC 2.1.3.6] catalyzes the reaction of carbamoyl phosphate with putrescine to produce orthophosphate and A-carbamoylputrescine. The plant enzyme will also catalyze the reactions of ornithine carbamoyltransferase, carbamate kinase, and agmatine deimmase. 

ASPARTYLCLUCOSAMINIDASE ASPARTATE AMINOTRANSFERASE ASPARTATE AMMONIA-LYASE ASPARTATE CARBAMOYLTRANSFERASE ASPARTATE a-DECARBOXYLASE ASPARTATE /3-DECARBOXYLASE ASPARTATE KINASE d-ASPARTATE OXIDASE ASPARTATE RACEMASE... 

ASPARTATE CARBAMOYLTRANSFERASE ATMOSPHERE ATOM PERCENT EXCESS TRACER/TRACEE RATIO COMPARTMENTAL ANALYSIS ISOTOPE EXCHANGE KINETICS ATOMIC MASS UNIT ATOMIC ORBITAL ATOMIZATION ATP... 

PUTRESCINE CARBAMOYLTRANSFERASE CARBANION Carbanion intermediates ENOLIZATION CARBENE... 

ORNITHINE TRANSCARBAMOYLASE d-ORNITHINE 4,5-AMINOMUTASE ORNITHINE AMINOTRANSFERASE ORNITHINE DECARBOXYLASE Ornithine carbamoyltransferase,... 

PURINE NUCLEOSIDE PHOSPHORYLASE PUTRESCINE CARBAMOYLTRANSFERASE PYRUVATE CARBOXYLASE... 

ASPARTATE CARBAMOYLTRANSFERASE NEGATIVE COOPERATIVITY POSTTRANSLATIONAL MODIEICATION OE PROTEINS... 

Ornithine carbamoyltransferase deficiency p Glnf, Citf, Alaj, Lysj, ArgJ,... 

Table 2.1.9 Changes of blood amino acids in various primary inherited defects and as a result of secondary changes. ASA Argininosuccinic acid, CPS carbamoyl phosphate synthase, LPI Lysinuric protein intolerance, MAD multiple acyl-CoA dehydrogenation, MSUD maple syrup urine disease, NAGS N-acetylglutamate synthase, NKH nonketotic hyperglycinemia, NTBC 2-(2-nitro-4-3 trifluoro-methylbenzoyl)-1,3-cyclohexanedione, OCT Ornithine carbamoyltransferase,...

Proteins are often organized into large complexes, sometimes for the purpose of regulating metabolism. An example is aspartate carbamoyltransferase... 

Figure 7-20 (A) Subunit assembly of two C3 catalytic trimers (green) and three R2 regulatory dimers around the periphery in aspartate carbamoyltransferase. After Krause et a/.109 Courtesy of William N. Lipscomb. The aspartate-and carbamoylphosphate-binding domains of the catalytic subunits are labeled Asp and CP, respectivley, while the zinc and allosteric domains of the regulatory subunits are labeled Alio and Zn, respectively. (B) Ribbon drawing of a single pair of regulatory (left) and catalytic (right) subunits with the structural domains labeled. MolScript drawing from Thomas et al.no...

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