Extended Data Fig. 3: The N-nitrosourea of SZN is derived from an intact guanidine group of l-arginine. | Nature

Extended Data Fig. 3: The N-nitrosourea of SZN is derived from an intact guanidine group of l-arginine.

From: An N-nitrosating metalloenzyme constructs the pharmacophore of streptozotocin

Extended Data Fig. 3

a, The mass spectrum of SZN [M − H2O + H]+ when 1 mM of [15N413C6]l-arginine was added to the fermentation culture. To determine whether the labelled SZN was a single isotopologue or a mixture, degradation (b) and MS/MS (c) experiments were performed. b, Exposure of SZN to ultraviolet light generated a one-carbon- and a one-nitrogen-labelled cyclic urea that was previously reported to be a denitrosated SZN product, indicating that the distal nitroso nitrogen is labelled9. c, MS/MS fragmentation of SZN revealed a one-carbon-labelled cyclic carbamate fragment, indicating that both of the N-nitroso nitrogens are labelled.

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