Phosphates and diphosphates

It is not clear whether the conditions used in the above experiments correspond to those present on the young Earth. Cyanate has been detected in cosmic nebulae (Yamagata, 1999), while water-soluble phosphates and diphosphates can be formed during volcanic activity, as Yamagata showed as early as 1991 (see Sect. 4.7.3). 

The leaving groups most commonly employed in nature are phosphates and diphosphates. These good leaving groups are anions of the strong acids phosphoric (pATa 2.1) and diphosphoric (pATa 1.5) acids respectively. The p a values given refer to the first ionization of these polyfunctional acids (see Section 4.7). 

Figure 1 Designing mimics of phosphates and diphosphates is difficult because of their anionic character and tetrahedral geometry (as indicated by p/(a values, bond lengths, and bond angles), (a) p/(a values for inorganic phosphate (12). (b) p/Ca values for pyrophosphate (12). (c) P-O bond lengths of the hydrogen phosphate dianion (13). (d) P-O bond angles in the hydrogen phosphate dianion (13).

Additional information <17, 21, 24, 30, 31, 35> (<21> substrate-substrate interaction between phosphate and diphosphate in forward and reverse reaction [26] <21, 35> kinetic product inhibition [16, 26, 33] <24, 31> kinetics, various inhibitors, forward and reverse reaction [12] <30> inhibition kinetics inhibition by product and inhibitors [9]) [9, 12, 16, 19, 26, 33]... 

M249L <1> (<1> site-directed mutagenesis, highly reduced activity and increased Km-value for fructose 6-phosphate compared to wild-type [38]) [38] R377A <1> (<1> site-directed mutagenesis, increased Km values for fructose 6-phosphate and diphosphate [40]) [40]... 

Y420A <1> (<1> site-directed mutagenesis, reduced activity, increased Km values for fructose 6-phosphate and diphosphate [40]) [40]... 

Ribulose is the ketose corresponding to ribose. In general, the ketoses are designated by the ending -ulose (unless they have trivial names, such as fructose). Xylulose is an epimer to ribulose at C-3. Ribulose phosphate and diphosphate play a role in biologic intereonversions of the sugars and in photosynthesis (Chapt. XVI-4). 

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