Deaminases histidine deaminase

Santisteban, I., Arredondo-Vega, F. X., Kelly, S., Debre, M., Fischer, A., Pdrignon, J. L., Hilman, B., Eldahr, J., Dreyfus, D. H., Howell, P. L., and Hershfield, M. S Four new adenosine deaminase mutations, altering a zinc-binding histidine, two conserved alanine, and a 5 splice site. Hum. Mutat. 5,243-250 (1995). 

Patel, B. T., Tudball, N., Wada, H. Watanabe T. (1986). Adenosine deaminase and histidine decarboxylase coexist in certain neurons of the rat brain. Neurosci. Lett. 63, 185-9. 

Bacterial electrodes [11, 31, 33, 46, 48, 49, 60] In this type of electrode, a suspension of suitable bacteria is placed between the sensor proper and a dialysis membrane that prevents passage of high-molecular substances (see fig. 8.3). The sensor is usually a gas probe. In the simple types of bacterial electrode, the determinand is converted by a suitable strain of bacteria into a product sensed by the gas probe. Thus it is possible to determine arginine [46], glutamine [48],/.-aspartic acid [31],/.-histidine [60] and nitrate [33]. Hybrid bacterial - enzyme electrodes contain both a bacterial strain and a suitable enzyme. For example, an extract from ivingas Neurospora chossa can be used as a source of NAD nucleosidase and an Escherichia coli culture as a source of nicotinamide deaminase, so that the electrode responds to NAD [49] as a result of the series of reactions... 

This enzyme [EC 4.3.1.3] (also known as histidinase, histidase, and histidine o -deaminase) catalyzes the conversion of histidine to urocanate and ammonia. See Dehydroalanine... 

Montero-Moran GM, Lara-Gonzalez S, Alvarez-Anorve LI et al (2001) On the multiple functional roles of the active site histidine in catalysis and allosteric regulation of Escherichia coli glucosamine 6-phosphate deaminase. Biochemistry 40 10187-10196... 

Histidine ammonia lyase (HAL, histidinase, histidine-a-deaminase, E.C. 4.3.1.3) is capable of abstracting ammonia from L-histidine (17), resulting in the formation of urocanoic acid [Scheme 12.6-4, (6)], an intermediate in the metabolism of l-histidine,n). HAL has also been identified as a key enzyme in the synthesis of secondary metabolites such as Nikkomycin in Streptomyces tendae,ul The mechanism of the enzyme has been investigated and seems to proceed via the carbanion intermediate111, 13]. Synthetic applications of HAL are difficult to achieve, particularly as the enzyme is sensitive to oxygen1131. The utility of HAL is limited to niche applications such as the synthesis of radiolabeled urocanic acids as tracers of histidine metabolism1"1. 

The deaminase domains are members of the cytosine deaminase superfamily. They bind catalytically essential Zn ions through complexation by one histidine and two cysteine residues. The reductase domains are members of the dihydrofolate reductase superfamily. In fact, the reactions catalyzed by pyrimidine reductase and dihydrofolate reductase are closely similar. Early in vivo work had shown that the hydride ion is incorporated into the 1 position. ... 

Myosin sufficiently purified in the usual way does not dephosphorylate any of the numerous phosphate compounds of living muscle other than ATP, and perhaps ITP, nor can it transphosphorylate. Menne (1943) finds that myosin, unlike the other main fractions of muscle, can convert arginine, histidine, glycocyamine, and choline into creatine. The myosin used, however, was only reprecipitated once and subsequently washed, and it is possible that the enzyme activity might be lost on further precipitation. After fractionation and precipitating three times, myosin possesses an appreciable adenylic deaminase activity (Hermann and Josepovits, 1949 Summerson and Meister, 1944). 

Nuclear relaxation studies of substrates and inhibitors have resulted in the detection of 10 enzyme-Mur-substrate and 4 enzyme-Mn-inhibitor bridge complexes possessing kinetic and thermodynamic properties consistent with their participation in enzyme catalysis. Three cases of a activation, by divalent cations, of enzyme-catalyzed enolization reactions (pyruvate carboxylase, yeast aldolase, v-xylose isomerase), and one case of 8 activation of an enzyme-catalyzed elimination reaction (histidine deaminase) have thereby been established, Thus, in each proven case, the enzyme-bound Mn coordinates an electronegative atom (Z) of the substrate, which is attached to a carbon atom one or two bonds away from the carbon atom which is to be deprotonated ... 

Histidine deaminase-Mn-imidazole Histidine deaminase-Mn-urocanate... 

An example of 8 activation has been established by the NMR method in the metal-activated histidine deaminase reaction (39). 

Figure 6. Mechanism of the histidine deaminase reaction (from Ref, 39 and 41)...

Another role of the Mn in histidine deaminase may be to mask the nucleophihc imidazole of the substrate to prevent its attacking the electrophilic center of the enzyme. 

It is noteworthy that three His, Glu, Asp or Cys residues provide zinc ligands for all known enzyme catalytic zinc sites [ 30], Water is the fourth ligand and histidine is by far the most frequent amino acid among the catalytic site residues. Three histidines are found in human carbonic anhydrases 1 and II, p-lactamase, the DD-carboxypeptidase of Streptomyces albus G, adenosine deaminase and astacin [30]. Two histidines are characteristic of bovine carboxypeptidases A and B, thermolysin and Escherichia coli alkaline phosphatase... 

Direct deamination of AMP to IMP by adenylate aminohydrolase (EC 3.5.4.6) occurs primarily in mammalian systems. It plays little, if any, role in bacteria where conversion usually occurs indirectly via deamination of adenine or adenosine [113,114]. Little is known about regulation at these levels, although adenosine deaminase is inducible by its substrate [114] and mutants lacking it have been obtained [115], Another indirect conversion in bacteria involves the regeneration of AlCAR, in the eventual conversion of phosphoribosyl-ATP (PR-ATP) to histidine. The AlCAR so obtained reenters the biosynthetic pathway and IMP is produced [33]. This pathway is regulated by histidine which exerts a profound feedback inhibition at the level of PR-ATP formation from ATP [116]. 

In mammals, histidine is an essential amino acid. Consequently, any inborn error leading to histidine accumulation in the blood is likely to result from an alteration in the breakdown pathway. The breakdown pathway of histidine starts with an enzyme called histi-dase, a histidine deaminase. The enzyme in liver catalyzes the conversion of the histidine to urocanic acid. The requirements of the purified liver enzymes are not clear. Although the rabbit enzyme requires folic acid, a divalent cation, and glutathione for activity, the guinea pig enzyme requires only the metal and the SH group. 

The system has been reviewed by Erkama and Virtanen. A similar reaction (discussed in the chapter. Carbon Catabolism of Amino Acids) is carried out by histidine deaminase to yield urocanic acid. 

The Japanese investigators " - proposed an alternate pathway, namely, that histidine was first deaminated to urocanic acid by an enzyme named by them histidine deaminase, and the urocanic acid, in... 

The enzyme which deaminates histidine to form urocanic acid has been called histidase, desaminohistidase, histidine deaminase, histidine-aenzyme preparation which degraded histidine to a product in which the imidazole ring had been split. This process is now known to consist of several steps. The name histidase was adopted by Mehler and Tabor 248) for the enzyme which converts histidine to urocanic acid and ammonia. Histidine deaminase, as a name, has the advantage of identifying the nature of the reaction. 

---