6-Diazo-5-oxo-norleucine

The ratio of the Michaelis constant of glutamine to inhibitor constants for azaserine and diazo-oxo-norleucine for the two amidotransferases of purine biosynthesis in pigeon liver are given in the accompanying tabulation. 

It may be seen that although diazo-oxo-norleucine is a much more potent inhibitor than azaserine, it is less selective. In contrast, azaserine is 60 times more effective than diazo-oxo-norleucine toward phosphoribosyl formylglycineamidine thetase. These ratios are markedly different when determined with the Salmonella enzyme, however (P). Azaserine, and presumably diazo-oxo-norleucine, bind covalently to a cysteine sulfhydryl of the enzyme, with the loss of the diazo group (10). 

Glutamine, ammonia, and a number of simple alcohols and amines can serve as substrates. The reaction is inhibited by reagents which react with sulfhydryl groups or which chelate iron, and by the glutamine analogue diazo-oxo-norleucine. Such inhibition is retarded in the presence of substrates. The affinity for glutamine is fairly low, the Michaelis constant being about 10 M. That for PP-ribose-P varies between 2 X 10 M and 2 X 10 M for different preparations (9, 12). 

Azaserine, diazo-oxo-norleucine, and some related compounds may be considered to be classical competitive inhibitors which act by reason of their structural resemblance to glutamine. Their action has already been discussed (Chapter 5). 

The glutamine analogue, diazo-oxo-norleucine, and the aspartate analogue, hadacidin (iV-formyl hydroxyaminoacetic acid), inhibit guanylate synthetase and adenylosuccinate synthetase, respectively. Alanosine (2-amino-3-nitrohydroxylaminopropionic acid) is also an inhibitor of adenylate synthesis from inosinate, but its mechanism of inhibition is not yet clear (52). 

As in other reactions in which either ammonia or the amide group of glutamine is utilized (amination of UTP to form CTP, synthesis of NAD from desamido-NAD, and of guanylate from xanthylate), the carbamyl phosphate synthetase II reaction is inhibited by the glutamine analogues, azaserine and diazo-oxo-norleucine (see Chapter 5). 

Subsequently, it was shown (50) that an extract from E. colt would utilize utamine or ammonia as the amino donor (the difference from earlier work apparently being due to changes occurring during the preparation of the enzyme). Diazo-oxo-norleucine inhibited the glutamine-supported reaction, but did not block ammonia utilization. The partly purified bacterial enzyme had a specific requirement for nonstoichiometric amounts of GTP. 

Miscellaneous antibiotics - Griseofulvin. the sideromycins and novobiocin known to affect varied processes in bacteria. can be included in this group. Also to be included are a number of antibiotics such as hadacidin. psicofuranine. tubercidin, toyocamycin. sangivamycin. azasering. diazo-oxo-norleucine (DON), cordycepin and mycophenolic acid known to block biosynthesis of some nucleic acid precursors. ... 

DON, see 6-Diazo-5-oxo-norleucine DONV, see 5-Diazo-4-oxo-L-norvaline Drugs, see aho specific substances binding to receptor, 574 opiate, see Opiate receptors Dye-ligand conjugate, 563 Dyes, 00... 

Diazoketone Formation. Reaction of carbamate derivatives of pyroglutamic acid esters with TMSC(Li)N2 below — 100°C gives the corresponding substituted 6-diazo-5-oxo-norleucine esters (eq 35). ... 

One example of a naturally occurring diazirine, duazomycin A (137 Scheme 11.20), has been reported, isolated in 1985 from a Streptomyces species during a screen for herbicidal compounds [196], It was fotind to inhibit de novo starch synthesis and it was suggested that this is due to direct inhibition of protein synthesis. Duazomycin A is structurally related to 6-diazo-5-oxo-L-norleucine (138), also reported as a natural product from Streptomyces [197], which acts as a glutamine antagonist and inhibits purine biosynthesis [198],... 

Nitrogen can be transferred from glutamine into many other substrates.102 Several antibiotic analogs of glutamine have been useful in studying these processes. Examples are the streptomyces antibiotics L-azaserine and 6-diazo-5-oxo-L-norleucine (DON). 

Chemical Name L-Norleucine, 6-diazo-N-(6-diazo-N-L-y-glutamyl-5-oxo-L-norleucyl)-5-oxo-... 

Two other residues which have been modified by affinity labels containing diazo linkages are sulfhydryl groups and histidine. Hartmann (1963) has shown that 6-diazo-5-oxo-L-norleucine (XXII),... 

A series of anti-metabolites have also been prepared which contain an alkylating moiety to enable the antagonists to inhibit the appropriate enzyme irreversibly, by formation of a co-valent bond94. Two compounds of this type to have had a clinical trial are the glutamine antagonists azaserine 44 and 6-diazo-5-oxo-L-norleucine (DON 45). 

Dion HW, Fusari SA, Jakubowski ZL, Zora JG, Bartz QR. 6-diazo-5-oxo-L-norleucine, a new tumor inhibitory substance 1. Isolation and characterization. J. Am. Chem. Soc. 78 3075-3077, 1956. 

Kisner DL, Catane R, Muggia FM. The rediscovery of DON (6-diazo-5-oxo-L-norleucine). Recent results. Cancer Res 74 258-263, 1980. 

Levenberg B, Melnick O, Buchanon JM. Biosynthesis of the purines. XV. The effect of aza-L-serine and 6-diazo-5-oxo-L-norleucine on the inosinic acid biosynthesis de novo. J. Biol. Chem. 225 163-176, 1957. 

Ovejera AA, Houchens DP, Catane R, Sheridan MA, Muggia FM. Efficacy of 6-diazo-5-oxo-L-norleucine and N-[N-gamma-glutamyl-6-diazo-5-oxo-norleucinyl -6-diazo-5-oxo-norleu-cine against experimental tumors in conventional and nude mice. Cancer Res. 39(8) 3220-3224, 1979. 

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