Carbamoyl sarcosine

Natural substrate (guanidinium) and inhibitors (carbamoyl) differ by the presence or absence of a positive charge on this part of the molecule. Thus, addition of water (as OH ) to the carbamoyl moiety and hydrolysis of the inhibitor would result in the development of charge rather than in its dispersal (as for the natural substrate ) in the partially hydrophobic environment of the active site. This explains why carbamoyl sarcosine acts as inhibitor for creatinase. In succinamic acid, the central NCH3 is replaced by CH2 and the proton transfer reaction (step 3) cannot occur. 

Two other hydantoinases are described in the literature, which have not yet been listed in the Enzyme Nomenclature 9. Siedel et al. 41, Yamada et al. 42, 43 and Ogawa et al.[44 found a new ATP-dependent 1-methylhydantoinase with additional nucleoside-triphosphatase activity 45 in different bacteria. This inducible enzyme, which was also shown to act on unsubstituted hydantoin and 5-methylhydantoin 41, is involved in the degradation of creatinine after its deimination in the 2-position to 1-methylhydantoin, resulting in N-carbamoylsarcosine (N-carbamoyl-N-methylgly-cine) 42, 43 (see Fig. 12.4-9). It is associated with a so-called D-N-carbamoylsarcosine hydrolase 43, which eventually hydrolyzes N-carbamoylsarcosine to free sarcosine. Both enzymes can be used for monitoring creatinine levels in blood 41. ... 

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