Irreversible Inhibition of Hypoxanthine Phosphoribosyltransferase Further Studies on the Specificity of Periodate-Oxidized GMP

Gutensohn, Wolf; Jahn, Heidi

doi:10.1515/bchm2.1977.358.2.939

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…The different capabilities of ox-inosine and ox-guanosine in binding to the human and schistosomal HGPRTases are similar to that observed previously by Gutensohn and Jahn (1977) and by Johnson et a]. (1979) on the human erythrocytic HGPRTase.…”

Section: Discussionsupporting

confidence: 89%

“…Another approach being pursued is to affinity label the enzymes with substrate analogs in an attempt to identify the amino acid residues near or within the active sites of the enzymes. Periodate-oxidized GMP, guanosine 2',3'-dialdehyde 5'-phosphate (ox-GMP), has been previously shown to irreversibly and specifically inactivate HGPRTare from rat brain and human erythrocytes (Gutensohn and Huber, 1975;Gutensohn and Jahn, 1977). In this report, we demonstrate that ox-GMP, which irreversibly inactivates the recombinant human and schistosomal HGPRTases, is specifically directed to the nucleotide binding site of both HGPRTases, thus satisfying the criteria of being an affinity label.…”

mentioning

confidence: 68%

“…A similar phenomenon was described by de Melo et al (1984) for the unexpected inactivation of the mitochondrial F,F,-ATPase by ox-AMP. Ox-IMP inhibits both human and schistosomal HGPRTases, whereas only marginal inhibition was demonstrable by oxinosine on the two enzymes (or the HGPRTase from human erythrocytes, Gutensohn and Jahn, 1977). Thus, the bindings of ox-IMP to the active sites in both enzymes and the binding of ox-GMP to human HGPRTase may all rely heavily on the presence of 5'-phosphate in nucleotide structure.…”

Section: Discussionmentioning

confidence: 99%

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Differential inhibitory effects of GMP‐2′,3′‐dialdehyde on human and schistosomal hypoxanthine–guanine phosphoribosyltransferases

Kanaaneh

Craig

Wang

1994

European Journal of Biochemistry

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The hypoxanthine–guanine phosphoribosyltransferase (HGPRTase) of human and the parasitic trematode, Schistosoma mansoni, were expressed at high levels in transformed Escherichia coli in their native forms. Guanosine 2′,3′‐dialdehyde 5′‐phosphate (ox‐GMP) was shown to bind irreversibly to both enzymes in a time‐dependent manner. This binding was stabilized by sodium borohydride reduction, suggesting that a Schiff's base is formed between the dialdehyde groups of ox‐GMP and the amino group of a lysine residue in the enzymes. This linkage formation applies also to inosine 2′,3′‐dialdehyde 5′‐phosphate but not to adenosine 2′,3′‐dialdehyde 5′‐phosphate. GMP was found to be protective against ox‐GMP inactivation and [3H]ox‐GMP labeling of both HGPRTases. 5‐Phosphoribosyl‐1‐diphosphate (PRibPP) also protects human HGPRTase against the ox‐GMP inactivation and [3H]ox‐GMP labeling but provides virtually no protection against the ox‐GMP inactivation and labeling of the schistosomal enzyme, even though PRibPP binds to the latter with a threefold higher affinity. These results imply that PRibPP and ox‐GMP compete with each other for binding to the human HGPRTase but not for binding to the schistosomal enzyme. This discrepancy could be exploited for the purpose of designing selective inhibitors of the schistosomal HGPRTase. Guanosine 2′,3′‐dialdehyde (ox‐guanosine) is nearly as active as ox‐GMP in inhibiting schistosomal HGPRTase but much less potent in inhibiting human HGPRTase, suggesting that ox‐guanosine and ox‐GMP may bind equally well to the parasite enzyme. PRibPP can protect human but not schistosomal HGPRTase against the inactivation by ox‐guanosine. Therefore, ox‐GMP and ox‐guanosine must be forming Schiff's bases with the same amino acid residues in each of the two HGPRTases.