Lysine mutase

Pyrolysis followed by catalytic hydrogenation then furnished the optically active 

6-methylpiperidones (49 and 50 in Fig. 27) whose absolute configurations were already known [43]. 

The final link in this cycle of circumstantial evidence was found by showing that a radioactive sample of enzymic origin, when processed to the urea derivative, cochromatographed with 47 but not with 48. 

A procedure for determining the absolute configuration of the tritiated succinic acid had already been developed, which involved partial oxidation on succinate dehydrogenase [45]. Applying this method it was then possible to show that the tritiated succinic acid of interest had the (S) configuration, and this in turn established the (5S) configuration of the tritiated /3-lysine from which it had been derived. Inspection of Fig. 28 reveals that the /3-lysine mutase reaction takes place with inversion at the C-5 of the substrate. 

---

Ethanolamine ammonia lyase, L-/ -lysine mutase, D-a-lysine mutase and ornithine mutase are representative of cobamide enzymes in which transfer of hydrogen occurs with cleavage of the C—N bond (Fig. 16). 

This cobalamin-dependent enzyme [EC 5.4.3.4], also called D-a-lysine mutase, catalyzes the interconversion of D-lysine and 2,5-diaminohexanoate. 

D-a-Lysine mutase and ornithine mutase catalyze the same type of reaction... 

Lysine mutase is the first of a group of AdoCbl-dependent enzymes that catalyses the 1,2-migration of an amino group (Fig. 26). It has been isolated from Clostridium sticklandii [39] and consists of a cobalamin-binding orange protein and a smaller yellow protein. Apart from AdoCbl, several other essential cofactors have been identified, such as pyridoxal phosphate, ATP, FAD, thiols, Mg2+ and K+ [38]. The function of the yellow protein and some of these cofactors is to renew continuously... 

Fig. 28. Steric course of the /3-lysine mutase reaction as it affects the C-5 of /3-lysine.

Aminomutases. The enzymes L-p-lysine mutase (which is also D-a-lysine mutase) and D-omithine mutase catalyze the transfer of an co-amino group to an adjacent carbon atom (Table 16-1). Two proteins are needed for the reaction pyridoxal phosphate is required and is apparently directly involved in the amino group migration. In the P-lysine mutase the 6-amino group of L-P-lysine replaces the pro-S hydrogen at C-5 but with inversion at C-5 to yield (3S, 5S)-... 

MethylmalonylCoA mutase Glutamate mutase a-Methylene-glutarate mutase Dioldehydrase Glyceroldehydrase Ethanoldeaminase L-/3-lysine mutase D-a-lysine mutase Ribonucleotide reductase Methionine synthetase Methane synthetase Methyl transferase Acetate synthetase... 

Lysine 2,3-aminomutase is not coenzyme 832 dependent, but a further lysine mutase, -lysine mutase (EC 5.4.3.3), catalyzes the coenzyme 812-dependent rearrangement shown in Scheme 68, the product 3,5-diaminohe-xanoic acid 261 having been shown (265) to have the (35,55) configuration. When the reaction was conducted in the presence of [5 - H] coenzyme 8,2 and the )5-lysine 258a was degraded to succinic acid, assay with succinate dehydrogenase showed the latter to be (25)-[2- HJ succinate (266). Thus... 

---