A very nice scheme of the ppGpp biosynthesis pathways can be found on the MetaCyc (1). Seems to be a very useful database in general.
References:
Caspi et al. The MetaCyc database of metabolic pathways and enzymes and the BioCyc collection of pathway/genome databases. NAR 2012 Jan;40(Database issue):D742-53 PIMD: 22102576
References:
Caspi et al. The MetaCyc database of metabolic pathways and enzymes and the BioCyc collection of pathway/genome databases. NAR 2012 Jan;40(Database issue):D742-53 PIMD: 22102576
